Welcome and introduction to Dihexa.co.uk

Introduction to Dihexa: definition, structure, classification, and basic information

How Dihexa is thought to work at the molecular and cellular level

Evidence-based overview of potential benefits based on preclinical and clinical research

Summary of scientific evidence, clinical trials, and current research status

Development history, clinical trials, and corporate context of Dihexa research

Dihexa's potential application in Alzheimer's disease and neurodegenerative conditions

Information on dosage ranges, protocols, and considerations for research use

Comprehensive overview of potential adverse effects, safety concerns, and risk factors

Dihexa in the context of cognitive enhancement and nootropic use

Comparative analysis of Dihexa against other nootropic compounds and peptides

Detailed analysis of Dihexa's legal status under UK law and regulatory framework

Comprehensive guide to buying research chemicals: quality, testing, COA, red flags, and best practices

Definitions of 30+ key terms: synaptogenesis, BDNF, LTP, blood-brain barrier, and more

Answers to common questions about Dihexa, research chemicals, and safety

In-depth guides and articles on Dihexa, nootropic stacking, peptide science, and cognitive enhancement

The complete pillar guide to brain fog for students, professionals, CEOs and anyone whose living depends on a sharp mind. Explains that brain fog is a symptom, not a diagnosis; the core symptoms (difficulty concentrating, slow thinking, forgetfulness, word-finding trouble, mental fatigue); the four underlying mechanisms (neuroinflammation, energy/fuel, hormones and neurotransmitters, and reduced BDNF plasticity signalling) with the 2024 Nature Neuroscience blood–brain-barrier long-COVID evidence and the Gladstone fibrin research; a full grouped map of the causes (sleep and burnout, nutrient deficiencies, hormonal and women's-health, medical, autoimmune and post-viral conditions, medications and environment) linking to every dedicated review; the evidence-based fixes (sleep, exercise and daylight, steady fuel and hydration, lowering the stress load, and ruling out medical causes with a GP blood panel); a dedicated section for students and high performers; an honest look at supplements and nootropics (caffeine + L-theanine, creatine, omega-3) and where the synaptogenic HGF/c-Met peptide Dihexa (PNB-0408) does and does not fit, including the fosgonimeton LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern; and clear guidance on when to see a doctor.

Rigorous 2026 UK evidence review comparing Alpha-GPC (choline alfoscerate / choline alphoscerate) and Dihexa (PNB-0408) for memory, focus and brain fog, written for students, athletes, founders, executives and high performers who reach for the choline in every focus stack and pre-workout. Covers what Alpha-GPC is (a highly bioavailable, blood-brain-barrier-crossing choline source and acetylcholine precursor), the cholinergic mechanism, the strongest human evidence in cognitive decline (the Sagaro/Traini/Amenta 2023 meta-analysis in the Journal of Alzheimer's Disease, the ASCOMALVA donepezil-plus-choline-alphoscerate trial and its 3-year brain-volume analysis, and the 2024 replication RCT), the famous Ziegenfuss 2008 growth-hormone and peak-bench-force resistance-exercise study, the reassuring 2025 South Korean nationwide delayed-dementia-conversion study, the balancing 2021 ten-year stroke-risk signal and the choline-to-TMAO cardiovascular mechanism, the 300-600 mg nootropic dose (up to 1,200 mg clinically) and side effects — versus Dihexa's unproven HGF/c-Met synaptogenesis, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern — and why a studied cholinergic with a nameable risk beats an experimental peptide.

Rigorous 2026 UK evidence review comparing Bacopa monnieri (Brahmi) and Dihexa (PNB-0408) for memory, brain fog and focus, written for the students, founders, executives and high performers who reach for the best-evidenced herbal memory aid. Covers what Bacopa is (the Ayurvedic medhya rasayana memory herb and its standardised bacoside extracts such as CDRI 08 / KeenMind / Synapsa), the structural mechanism (cholinergic acetylcholinesterase inhibition, hippocampal antioxidant protection, enhanced dendritic arborisation and preclinical BDNF), the strongest human evidence (the Stough 2001 Psychopharmacology 12-week verbal-learning and memory-consolidation RCT where benefits appeared at 12 weeks but not 5, the Calabrese 2008 elderly cognition, anxiety and depression trial, the Kongkeaw 2014 Journal of Ethnopharmacology meta-analysis of 6 RCTs and 437 subjects showing improved delayed recall, Trail B and choice reaction time, and the 2021 Frontiers in Aging Neuroscience brain-microstructure study), the practical 300 mg standardised dose taken with food over an 8–12 week course, the gastrointestinal side effects and drug interactions, and the live 2026 JMIR amnestic MCI / early Alzheimer's trial — versus Dihexa's unproven HGF/c-Met synaptogenesis, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern — and why, for memory, the studied, low-cost herb beats an experimental peptide.

Evidence-based 2026 UK guide to the best nootropics for studying, focus and memory, written for students, founders, CEOs and high performers and ranking every option by human proof. Covers what actually counts as a nootropic, the free Tier-1 foundation (sleep, exercise, diet, spaced repetition and active recall), the best-evidenced caffeine + L-theanine 2:1 calm-focus study stack (the 2026 Molecular Psychiatry meta-analysis of 31 randomised trials and the 2025 British Journal of Nutrition sleep-deprivation study), creatine for cognitive energy in the tired brain, omega-3, L-tyrosine and rhodiola, the prescription study drugs (modafinil and the Battleday & Brem 2015 systematic review, prescription stimulants, the UK legal position, side effects, academic integrity and UK student prevalence), the racetam and peptide tier (Semax, Selank, Noopept, phenylpiracetam, Lion's Mane, bromantane), and where the synaptogenic HGF/c-Met peptide Dihexa (PNB-0408) sits — with no completed human trial for studying, the fosgonimeton LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern — plus a practical build-your-stack-by-goal playbook, and why the boring, legal basics beat an experimental peptide.

Rigorous 2026 UK evidence review comparing L-theanine and Dihexa (PNB-0408) for brain fog, focus and calm, written for the founders, executives, traders, clinicians and students who rely on the “calm focus” nootropic stack. Covers what L-theanine is (the amino acid in tea, Camellia sinensis), the mechanism (crossing the blood-brain barrier to raise alpha brain waves and gently modulate GABA, glutamate, dopamine and serotonin for “relaxation without sedation”), the strongest 2026 evidence (the Molecular Psychiatry systematic review and meta-analysis of 31 randomised trials in 1,168 people, a single 200 mg dose improving choice reaction time), the famous caffeine + L-theanine 2:1 calm-focus stack (Owen and Haskell 2008, Nobre 2008, and the 2025 British Journal of Nutrition sleep-deprivation selective-attention study), the stress and sleep data (the 2024 AlphaWave 28-day stress RCT in Neurology and Therapy, the 2019 Nutrients RCT, Kimura 2007 cortisol, and the 2025 Sleep Medicine Reviews sleep meta-analysis), the honest EFSA 2011 non-substantiation of the cognitive, stress and sleep claims, the excellent safety profile (GRAS status, no serious adverse effects to 900 mg/day for 8 weeks, no tolerance or withdrawal) and UK dosing, versus Dihexa's unproven HGF/c-Met synaptogenesis, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern — and why, for everyday focus and stress-related fog, the cheap, safe, legal tea amino acid beats an experimental peptide comprehensively.

Rigorous 2026 UK evidence review comparing ashwagandha (Withania somnifera) and Dihexa (PNB-0408) for brain fog, cortisol, stress and focus, written for the executives, founders, students and high performers driving the 2025–2026 cortisol and adaptogen boom. Covers the real mechanism (lowering the stress hormone cortisol that impairs the prefrontal cortex and hippocampus, a GABA-mimetic calming action and a proposed mild acetylcholinesterase-inhibiting effect that preserves acetylcholine), the human randomised controlled trials that set it apart from most brain-fog fads — Chandrasekhar 2012 (~27.9% cortisol reduction), Choudhary 2017 in the Journal of Dietary Supplements (improved memory, attention, processing speed and executive function in mild cognitive impairment), Salve 2019 in Cureus and Gopukumar 2021 in healthy stressed adults — why the cognitive benefit is largest in people with high baseline stress and negligible in the calm, the honest reading of small, often industry-funded trials, the genuine 2025 safety story of ashwagandha-associated liver injury (the NIH LiverTox database, the ACG 2025 herbal-supplement-induced liver injury systematic review, and Lareb, TGA and MHRA Yellow Card warnings), the thyroid, blood-sugar, blood-pressure, autoimmune and pregnancy cautions, the untested-UK-supplement quality problem, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern — and why sleep, exercise and stress control come first, a studied adaptogen is a considered option, and an unproven peptide is no option at all.

Rigorous 2026 UK evidence review comparing methylene blue and Dihexa (PNB-0408) for brain fog and cognitive energy, written for the high performers, executives, students and biohackers driving the viral methylene blue trend. Covers the early-2025 search spike after methylene blue featured in wellness and biohacking media, the mitochondrial mechanism (a redox-cycling alternative electron carrier that feeds electrons to cytochrome c oxidase / Complex IV, raising ATP, cerebral oxygen use and blood flow, and crossing the blood-brain barrier easily), the 2016 Radiology randomised double-blind fMRI study in 26 healthy adults (increased insular and memory-network activity and a ~7% rise in memory retrieval on a single low dose), the honest limits of that thin human evidence, the TauRx hydromethylthionine mesylate (HMTM / LMTM / TRx0237) tau-aggregation-inhibitor derivative that reached the Phase 3 LUCIDITY Alzheimer's trial and a July 2024 UK MHRA marketing authorisation application under the ILAP, the FDA drug safety communication on serotonin syndrome from MAO-A inhibition (a real risk with SSRIs, SNRIs, tricyclics, triptans, tramadol and MAOIs), G6PD-deficiency haemolysis, the pharmaceutical-versus-industrial-grade purity problem, the parallel fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern, and why fixing sleep, exercise, fuel and any medical cause comes first, not a dye or a peptide.

Rigorous 2026 UK evidence review of whether jet lag causes brain fog — and whether a synaptogenic HGF/c-Met peptide like Dihexa has any role — written for the business travellers, executives, students and frequent flyers who search for it. Unusually for this series the science is solid: jet lag disorder is a recognised circadian rhythm sleep-wake disorder (CDC Yellow Book 2026) whose symptoms include impaired concentration and cognition, because crossing time zones forces the brain to work during its biological night. Covers the master body clock (the suprachiasmatic nucleus) and light as the dominant zeitgeber, the ~one-time-zone-per-day re-entrainment rule and why eastward travel is harder, the 2020 neuroimaging study linking jet lag to reduced parietal-cortex working-memory activation, the landmark Cho 2001 Nature Neuroscience cabin-crew study (shorter recovery linked to higher cortisol, a smaller right temporal lobe and worse spatial memory), the experimental-jet-lag hippocampal-neurogenesis and BDNF suppression mechanism, the 2026 shift-work brain-volume findings, the Cochrane melatonin review and the MHRA-licensed, prescription-only jet-lag melatonin, the light-timing, sleep, caffeine and napping toolkit, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern, and why light, a schedule and melatonin come first, not a peptide.

Rigorous 2026 UK evidence review of whether ketogenic and low-carb diets cause brain fog or clear it — and whether a synaptogenic HGF/c-Met peptide like Dihexa has any role. Separates the transient “keto flu” (a sodium, fluid and electrolyte problem during the glucose-to-ketone switch that a 2025 scoping review shows usually starts within 2–3 days and resolves within 2–4 weeks) from the deeper ketone-and-cognition question: the 2026 PLoS ONE study finding three weeks of keto made students “faster but less accurate”, the Neurology case report of reversible memory loss and brain fog on prolonged strict keto, the beta-hydroxybutyrate (BHB) HDAC-inhibitor BDNF pathway (Sleiman 2016 eLife) and the honest 2025 human study finding raising BHB did not increase BDNF or improve cognition, the 2026 Frontiers in Nutrition exogenous-ketone meta-analysis, the MCI and Alzheimer’s ketone-as-alternative-fuel trials, the low-carb type 2 diabetes remission data (up to ~62% at one year, ~13% by five years) with Diabetes UK and HEART UK guidance, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern, and why replacing electrolytes and giving adaptation two weeks come first, not a peptide.

Rigorous 2026 UK evidence review of whether microplastics and nanoplastics cause brain fog — and whether a synaptogenic HGF/c-Met peptide like Dihexa has any role. Tied to the February 2025 Nature Medicine study that found micro- and nanoplastics (mostly polyethylene) accumulating in the human frontal cortex at 7–30× the level of liver or kidney, about 50% higher in 2024 than 2016, and markedly higher in the brains of people with a dementia diagnosis. Explains why nanoplastics cross the blood-brain barrier, the ~240,000-particles-per-litre bottled-water finding, the Duke alpha-synuclein / Parkinson’s aggregation mechanism, the University of Rhode Island mouse study linking microplastics to neuroinflammation and dementia-like behaviour, the neuroinflammation / oxidative-stress model, the honest limits (correlation not causation, the contested “plastic spoon” mass, the reverse-causation trap in dementia brains, the WHO caveat), the UK microbead ban and regulatory gap, practical exposure-reduction steps, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern, and why reducing exposure and treating the real causes of brain fog come first, not a peptide.

Rigorous 2026 UK evidence review of whether seed oils and their main omega-6 fat, linoleic acid, cause brain fog — and whether a synaptogenic HGF/c-Met peptide like Dihexa has any role. Tied to the “toxic seed oils” culture war (the RFK Jr / MAHA beef-tallow campaign) and the January 2026 US dietary-guidelines shift that stopped highlighting seed oils and added butter and tallow. Steelmans the case against seed oils (the omega-6→arachidonic-acid inflammation theory, the omega-6:omega-3 ratio, oxidation and industrial processing, and seed oils as the fingerprint of ultra-processed food) then tests it against the human evidence: randomised trials showing linoleic acid does not raise CRP, the NUTRITION 2025 biomarker study of ~1,900 adults linking higher linoleic acid to lower inflammation and cardiometabolic risk, the 2026 UK Biobank study of 81,827 people finding ~18% lower dementia risk in the highest linoleic-acid group (and that non-linoleic omega-6 behaves differently), the 2013 systematic review showing the omega-6:omega-3 ratio is a weak, inconsistent predictor of cognition, the genuine kernels of truth (reheated deep-frying oil and the ultra-processed pattern), the NHS Eatwell Guide, British Heart Foundation and HEART UK positions, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern, and why fixing the overall diet pattern and raising omega-3 come first, not a peptide.

Rigorous 2026 UK evidence review comparing omega-3 (fish oil, DHA and EPA) and Dihexa (PNB-0408) for brain fog and cognition, tied to the February 2025 DO-HEALTH trial in Nature Aging showing 1 g/day omega-3 slowed biological ageing by up to ~4 months on epigenetic clocks (additively with vitamin D and exercise). Covers why the brain is physically built from DHA (the most abundant omega-3 in neuronal and synaptic membranes), EPA’s anti-inflammatory role and the neuroprotectin D1 / resolvin pro-resolving mediators, the human evidence — the Framingham red-blood-cell DHA data (highest quintile ~49% lower Alzheimer’s risk and ~4.7 extra AD-free years), the 2022 midlife omega-3-index and hippocampal-volume study, and the ~20% lower dementia/cognitive-decline risk from dietary omega-3 — the honestly mixed supplement-trial picture, the APOE4 blood-brain-barrier and timing question, the honest atrial-fibrillation caveat with high-dose fish oil (the 2021 Circulation meta-analysis and the December 2025 UK Biobank JAHA analysis), the NHS two-portions-of-oily-fish and EFSA 250 mg EPA+DHA guidance, the head-to-head on evidence, safety, UK legality and cost, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern, and why oily fish comes first, not a peptide.

Rigorous 2026 UK evidence review of whether caffeine causes brain fog and whether a synaptogenic HGF/c-Met peptide like Dihexa has any role, tied to the record May 2026 dementia study (~35% lower risk at 2–3 cups a day) and the UK Government’s move to ban high-caffeine energy drinks for under-16s (consultation closed 26 November 2025). Explains that most “caffeine brain fog” is really three different fogs — the crash from rebound adenosine, caffeine withdrawal (a 2022 Scientific Reports RCT showing reduced working-memory brain activity), and the sleep tax of late caffeine given its 5–6 hour half-life — the adenosine A1/A2A antagonist mechanism, tolerance and adenosine-receptor up-regulation, the reassuring coffee-and-dementia epidemiology (UK Biobank slower decline, lower Alzheimer’s and Parkinson’s), the caffeine–BDNF plasticity link, energy drinks and young brains, the EFSA 400 mg and NHS pregnancy 200 mg limits, the head-to-head on evidence, safety, cost and UK legality, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern, and why caffeine hygiene and sleep, not a peptide, come first.

Rigorous 2026 UK evidence review of whether ultra-processed food (UPF) causes brain fog and whether a synaptogenic HGF/c-Met peptide like Dihexa has any role, tied to 2026’s biggest diet story and the UK Scientific Advisory Committee on Nutrition (SACN) 2025 rapid evidence update. Covers the NOVA classification and what “ultra-processed” actually means (UPFs now make up well over half of average UK calories), the human evidence — the May 2024 Neurology study linking higher UPF intake to faster cognitive decline and stroke, the 2025 Neurology study tying 11+ UPF servings a day to a 2.5× higher rate of prodromal Parkinson’s features, 2025 brain-reward “rewiring” and overeating research, and 2026 dementia and systematic-review data — the blood-sugar, gut–brain-axis, systemic-inflammation and nutrient-crowding mechanisms, the head-to-head on evidence, safety, cost and UK legality (diet vs an unlicensed research chemical), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure and the pro-proliferative c-Met concern, and why cutting ultra-processed food comes first, not a peptide.

Rigorous 2026 UK evidence review comparing creatine and Dihexa (PNB-0408) for brain fog and cognitive energy, tied to the 2025–2026 creatine boom (mainstream sales up ~72% year-on-year, creatine-gummy searches up >1,300%, and a fast-growing women’s, menopause and older-adult brain-health audience). Covers what creatine actually is and why the brain cares (the phosphocreatine “backup battery” that regenerates ATP under load, raising brain phosphocreatine ~5–15%), the human evidence — the Gordji-Nejad 2024 Scientific Reports single-dose (0.35 g/kg) sleep-deprivation study improving processing speed and working memory, the 2023 memory meta-analysis and 2024/2025 cognition and ageing systematic reviews showing modest benefits strongest in older, sleep-deprived, stressed and vegetarian people, and the 2025 University of Kansas Alzheimer’s creatine pilot (20 g/day, brain creatine +11%) — versus Dihexa’s HGF/c-Met synaptogenesis mechanism with no completed human cognition trial (Benoist 2014 JPET pre-clinical only), the head-to-head on evidence, safety (ISSN position stand vs the pro-proliferative c-Met concern), UK legality and cost, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, and why the cheap, safe, evidence-backed option comes first.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in low testosterone, hypogonadism or “andropause” (male menopause) brain fog, tied to the 2026 boom in private UK testosterone clinics (~40 clinics) and The Pharmaceutical Journal’s warning on the “worrying rise of testosterone replacement therapy”. Covers how testosterone acts on androgen receptors in the hippocampus, prefrontal cortex and mesocorticolimbic dopamine system, the dendritic-spine finding (androgen deficiency reduces mature mushroom spines; replacement prevents this), the mixed cognitive evidence — the Testosterone Trials (Resnick, JAMA 2017) finding no memory or cognitive benefit versus the 2025 androgen-therapy systematic review and meta-analysis showing modest executive-function and memory gains in hypogonadal men with publication bias, why most midlife “andropause” symptoms have other treatable causes (sleep apnoea, insomnia, depression, chronic stress, type 2 diabetes, B12/iron/vitamin D deficiency, thyroid, alcohol, ADHD), the NHS position on the “male menopause”, the importance of proper diagnosis with repeated morning blood tests over clinic symptom quizzes, the BDNF and HGF/c-Met synaptogenesis case (Benoist 2014 JPET), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, the pro-proliferative c-Met and prostate-cancer concern, and why diagnosing and treating the hormone, not a peptide, comes first.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in “brain rot” or digital brain fog. Covers Oxford University Press’s 2024 Word of the Year (usage up ~230%) and the 2026 rise in digital-brain-fog searches, why brain rot is a behavioural and largely reversible state rather than a neurodegenerative disease, how constant task-switching and notifications train shallow attention, the Loh & Kanai 2014 PLoS ONE media-multitasking and anterior-cingulate grey-matter finding (correlation, not causation), the variable-reward dopamine loop that leaves ordinary tasks feeling flat, the sleep-disruption multiplier, the doomscrolling–anxiety–low-mood feedback loop, the reassuring 2025 scoping review showing screen-time effects on cognition are mixed and context-dependent with no strong evidence of permanent damage in healthy adults, the risk of mislabelling a treatable medical fog (thyroid, B12, iron, vitamin D, sleep apnoea, anxiety, depression, ADHD, menopause, long COVID) as “brain rot”, the digital-hygiene, sleep, attention-retraining, exercise and daylight interventions that actually work, the BDNF and HGF/c-Met synaptogenesis case (Benoist 2014 JPET), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, the pro-proliferative c-Met concern, and why digital hygiene, not a peptide, comes first.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in dehydration or heat-related brain fog, tied to the record-breaking June 2026 UK heatwave and UKHSA red heat-health alerts. Covers how a 1–2% body-water loss measurably impairs attention, working memory, concentration and mood (Ganio 2011 in men, Armstrong 2012 in women), how dehydration shrinks brain tissue and forces it to work harder for the same output (Kempton 2011 fMRI), passive hyperthermia degrading working memory and executive function independently of hydration (Gaoua), the cortisol, cerebral-blood-flow and electrolyte mechanism, the fast reversibility of mild dehydration fog with rehydration, the NHS hydration and electrolyte guidance, the PoTS / migraine / menopause / ME/CFS / older-brain overlap, the BDNF and HGF/c-Met synaptogenesis case (Benoist 2014 JPET), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, the pro-proliferative c-Met concern, and why rehydrating and cooling down, not a peptide, comes first.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in hay fever or antihistamine-related brain fog. Covers UK allergic-rhinitis prevalence (~16 million people, ~26% of adults; the UK among the highest-prevalence countries), the June–July grass-pollen peak and Met Office forecast, histamine as a brain wakefulness neurotransmitter supporting attention and working memory, the neuroinflammation (TNF-α, IL-6) and reduced hippocampal-prefrontal coupling shown in allergic-rhinitis studies, congestion and disturbed sleep, the central twist that sedating first-generation antihistamines (chlorphenamine/Piriton, diphenhydramine, promethazine, hydroxyzine) cross the blood-brain barrier and occupy >80% of brain H1 receptors and cause the fog themselves, the NHS preference for non-drowsy antihistamines (cetirizine, loratadine, fexofenadine) plus steroid nasal sprays and immunotherapy, the anticholinergic-burden and dementia research (the 2025 Swedish nationwide case-control study and the 2024 H1-antihistamine cumulative-dose study) handled without alarmism, the histamine-intolerance / MCAS / PoTS / long COVID overlap, the BDNF and HGF/c-Met synaptogenesis case (Benoist 2014 JPET), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, the pro-proliferative c-Met concern, and why treating the allergy and switching the antihistamine, not a peptide, comes first.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in insomnia or sleep-deprivation-related brain fog. Covers the ~one-third of UK adults reporting insomnia symptoms and the 2024 UK Biobank prevalence study (~29% self-reported vs ~6% recorded in primary care), the synaptic homeostasis hypothesis (Tononi & Cirelli 2014 Neuron), the glymphatic overnight waste-clearance system and amyloid-beta link to long-term cognitive and dementia risk, hippocampus-dependent memory consolidation failure, the 2020 CD44 blood-brain-barrier permeability study and 2026 neurobiological memory review, the reversibility of acute sleep-loss cognition with recovery sleep, the first-line CBT-i and NICE-recommended Sleepio digital programme, benzodiazepine and Z-drug short-term-only prescribing, the orexin-receptor antagonist daridorexant (Quviviq) under NICE TA922, the burnout / anxiety / menopause / obstructive sleep apnoea / long COVID overlap, the BDNF and HGF/c-Met synaptogenesis case (Benoist 2014 JPET), the vivid-dreams mismatch (a sleep-disrupting peptide for a sleep disorder), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, the pro-proliferative c-Met concern, and why fixing the sleep, not a peptide, comes first.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in air-pollution-related brain fog. Covers fine particulate matter (PM2.5) and traffic-fume cognition, the ~29,000–43,000 UK deaths a year attributed to long-term PM2.5 and NO₂ exposure (COMEAP / UKHSA), the 2024 Lancet Commission naming air pollution one of 14 modifiable dementia risk factors (~3% of cases, ~1.65 million globally), the 2025 King’s College London study of the 1946 British Birth Cohort (Insight 46) linking midlife exposure to slower processing speed and brain-structure change, the 2025 Lancet Planetary Health meta-analysis, the microglial-activation / blood-brain-barrier / olfactory-route neuroinflammation model, oxidative stress and the vascular route to cognitive decline, the WHO 2021 no-safe-level PM2.5 guideline (5 µg/m³), Ella’s Law (the Clean Air (Human Rights) Bill) named after Ella Adoo-Kissi-Debrah and re-introduced to the Commons on 1 July 2025 with a further reading on 27 March 2026, the long COVID / ME/CFS / migraine / vascular overlap, the BDNF and HGF/c-Met synaptogenesis case (Benoist 2014 JPET), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, the IARC Group 1 carcinogen c-Met red flag (lung cancer), and why cleaner air, not a peptide, comes first.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in mould- and mycotoxin-related brain fog. Covers the English Housing Survey 2023–24 damp figures (~1.3 million English homes, a 5-year high), Awaab’s Law coming into force on 27 October 2025 and its 2026–27 expansion, the WHO 2009 indoor-air-quality dampness-and-mould guidelines (up to 75% greater respiratory risk), the NHS position on damp and mould, the innate-immune / NLRP3-inflammasome neuroinflammation model, the 2020 Harding Brain, Behavior, and Immunity study showing inhaled Stachybotrys spores raised hippocampal IL-1β, cut dentate-gyrus neurogenesis and caused memory deficits, blood-brain-barrier disruption, oxidative stress and mitochondrial dysfunction, the contested CIRS / “toxic mould illness” model (Shoemaker, HLA-DR, biotoxins) and why it is not a mainstream NHS diagnosis, the ME/CFS, long COVID, fibromyalgia and gut-brain overlap, the BDNF and HGF/c-Met synaptogenesis case (Benoist 2014 JPET), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, the mycotoxin–carcinogen c-Met red flag (aflatoxin B1 as a liver carcinogen, ochratoxin A), and why removing the exposure, not a peptide, comes first.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in Epstein-Barr virus (EBV) or glandular fever (infectious mononucleosis) brain fog and post-viral cognitive symptoms. Covers EBV carriage in ~90–95% of adults, glandular fever incidence (~5 per 1,000, peaking at age 15–24), post-viral fatigue and the ~60% infectious-onset figure in ME/CFS, EBV reactivation, the neuroinflammation / microglial-activation / hippocampal mechanism, autophagy interference and mitochondrial dysfunction, the landmark 2022 Ascherio Science study showing a 32-fold rise in multiple sclerosis risk after EBV, the Lanz 2022 Nature EBNA1–GlialCAM molecular-mimicry mechanism, the 2023 Lancet Neurology prevention-and-therapy review, the Moderna mRNA EBV vaccine Phase 2 trial in early relapsing MS (NCT06735248) and the NIH gp350-ferritin nanoparticle vaccine, the long COVID overlap (~67% EBV reactivation vs ~10% controls; the 2022 Su Cell study), the BDNF and HGF/c-Met synaptogenesis case (Benoist 2014 JPET), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, the EBV-specific c-Met oncology red flag (Burkitt and Hodgkin lymphoma, nasopharyngeal carcinoma, gastric cancer, post-transplant lymphoproliferative disease), NICE NG206 pacing guidance, and why structured recovery, not a peptide, comes first.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in Sjögren’s syndrome brain fog (“Sjögren’s fog”) and Sjögren’s-associated cognitive dysfunction. Covers the up-to-500,000 UK prevalence and Sjögren’s status as the second most common autoimmune rheumatic disease after rheumatoid arthritis, the ~44–50% measurable cognitive impairment, ~25–30% neurological involvement, ~50% autonomic dysfunction and ~70% disabling fatigue, the 2025 BSR (British Society for Rheumatology) guideline on adult and juvenile-onset Sjögren disease, the anti-Ro/SSA and anti-La/SSB autoantibody story, the type I interferon and BAFF/BLyS biology, the neuroinflammation / small-vessel / white-matter mechanism of CNS involvement, small fibre neuropathy and dysautonomia, the 2025 PLOS One BACE1 / inflammatory cognitive-biomarker study, the Novartis ianalumab (VAY736) NEPTUNUS-1/NEPTUNUS-2 Phase 3 success and January 2026 FDA Breakthrough Therapy designation, the Johnson & Johnson nipocalimab FcRn-blocker DAHLIAS Phase 2 trial (The Lancet, 2025) and Phase 3 DAFFODIL programme, the negative JOQUER hydroxychloroquine (JAMA 2014) and TRACTISS rituximab trials, the symptomatic care pathway (artificial tears, pilocarpine, cevimeline), the HGF/c-Met and BDNF synaptogenesis case (Benoist 2014 JPET), the elevated B-cell (MALT) lymphoma risk versus pro-proliferative c-Met activation, and why specialist rheumatology care, not a peptide, comes first.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in SSRI- and antidepressant-related brain fog and emotional blunting. Covers the record NHSBSA 2024/25 prescribing figures (92.6 million antidepressant items dispensed to ~8.89 million patients in England), the 40–60% emotional-blunting estimate, the January 2023 University of Cambridge escitalopram study linking SSRIs to reduced reward sensitivity and impaired reinforcement learning, the BDNF paradox (SSRIs generally raise BDNF and hippocampal neurogenesis via 5-HT1A/5-HT4 signalling, so antidepressant fog is not a synapse-deficiency a peptide refills), residual cognitive impairment across attention, response inhibition, verbal memory, decision speed and processing that persists after mood improves, the directionality problem in the 2024 cognitive-impairment analysis, antidepressant discontinuation/withdrawal symptoms and NICE NG222 gradual-tapering guidance, post-SSRI sexual dysfunction (PSSD) and its 2024 SNOMED CT recognition, the c-Met cancer and serotonergic-interaction cautions, the HGF/c-Met synaptogenesis case (Benoist 2014 JPET), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, and why a prescriber-led dose review, switch or taper — not a peptide — comes first.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in vaping- and nicotine-related brain fog. Covers the 1 June 2025 UK disposable-vape sales ban and the Tobacco and Vapes Act 2025 (smoke-free generation, Vaping Products Duty), ASH 2025 youth-vaping data (~1.1 million 11–17s have tried vaping, ~400,000 current, 4.2% of never-smokers), the nicotine paradox of acute cognitive enhancement via α4β2 and α7 nicotinic acetylcholine receptors versus tolerance, dependence and withdrawal-related deficits in sustained attention, working memory and response inhibition, the 2024 Psychopharmacology e-cigarette cognition scoping review (impaired memory, concentration and decision-making in smokers and never-smokers), the adolescent prefrontal-cortex vulnerability, the nicotine–BDNF–α7 nAChR working-memory link, the 2025 cerebrovascular vaping study, the c-Met cancer caution, the HGF/c-Met synaptogenesis case (Benoist 2014 JPET), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, and why quitting nicotine with NHS stop-smoking support, not a peptide, clears vape brain fog.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in burnout-related brain fog. Covers the record HSE 2024/25 work-related stress figures (964,000 GB workers, 52% of all work-related ill health, 22.1 million working days lost), the Mental Health UK Burnout Report 2026 (91% high or extreme pressure; 20% took time off, 39% of 18–24s), the WHO ICD-11 definition of burnout as an occupational phenomenon with three dimensions, the clinical-burnout cognition meta-analysis (executive function, attention, episodic and working memory) and the 2025 resting-state EEG burnout study, the cortisol / HPA-axis story and why established burnout is dysregulation rather than simply “high cortisol” (blunted responses, flattened rhythm, hypocortisolism), chronic-stress hippocampal CA3 synapse loss and suppressed neurogenesis, chronic-stress BDNF reduction, the BDNF / HGF–c-Met synaptogenesis case (Benoist 2014 JPET), the masking and stimulant-trap risks unique to burnout, the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, and why rest, recovery and reducing the load come first, not a peptide.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in gut-brain axis brain fog from irritable bowel syndrome (IBS, ~10–20% prevalence), small intestinal bacterial overgrowth (SIBO), increased intestinal permeability (“leaky gut”) or a disrupted microbiome. Covers the 2024 “Gut Feelings” probiotic and prebiotic cognition RCT (weak working-memory benefit), the long-COVID Lactobacillus paracasei PS23 brain-fog trial (NCT06348212), the microbiota–gut–brain axis signalling routes (vagus nerve, short-chain fatty acids such as butyrate, immune and endocrine pathways), the microbiome–BDNF/TrkB connection and SCFA-producer depletion (Faecalibacterium prausnitzii, Bifidobacterium), NICE CG61 and NHS IBS guidance, the low-FODMAP diet and probiotic evidence, the c-Met / gastrointestinal-cancer caution, HGF’s dual role in intestinal epithelial repair and brain synaptogenesis (Benoist 2014 JPET), the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure, and why diagnosing and treating the gut comes first, not a peptide.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in cannabis brain fog or weed brain fog. Covers the January 2025 JAMA Network Open working-memory fMRI study of 1,003 young adults (63% of heavy lifetime and 68% of recent users showing reduced dorsolateral/dorsomedial prefrontal and anterior-insula activity); how THC acts as a partial agonist at CB1 receptors dense in the hippocampus and prefrontal cortex and how the endocannabinoid system cross-talks with BDNF and adult neurogenesis (CB1-knockout BDNF reduction; biphasic, dose-dependent THC effects on BDNF); UK prevalence (cannabis the most-used illicit drug, ~1 in 7 of 16–24s in the past year) and cannabis use disorder; why cannabis-related cognition largely recovers after abstinence (Scott 2018 JAMA Psychiatry meta-analysis, deficits diminishing past ~72 hours); high-potency “skunk” and psychosis risk; synthetic cannabinoids (“Spice”) and cannabinoid hyperemesis syndrome; CBD and balanced-ratio medical cannabis; the May 2025 London Drugs Commission decriminalisation report; the BDNF–HGF–c-Met synaptogenesis chain; the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure as a cautionary analogue; and why a tolerance break comes first, not a peptide.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in peripheral nerve regeneration. Covers how hepatocyte growth factor (HGF) / c-Met activates “repair” Schwann cells to drive peripheral nerve regeneration (Ko et al. 2018, Scientific Reports); the 2021 Annals of Medicine and Surgery rat sciatic-nerve transection-repair study in which Dihexa plus mesenchymal stem cells improved motor recovery and reduced foot-flexion contractures; the VM202 / Engensis plasmid-DNA HGF gene-therapy Phase 3 in painful diabetic peripheral neuropathy (Kessler 2021; NCT04469270 results posted January 2025); chemotherapy-induced peripheral neuropathy (CIPN) and the ASCO duloxetine recommendation; the Benoist 2014 JPET HGF/c-Met mechanism behind Dihexa; the 2026 Athira-to-LeonaBio pivot taking the oral HGF/MET positive modulator ATH-1105 into a Phase 2 ALS trial; NICE NG19 and CG173 pathways; the c-Met oncology caution; and the complete absence of any human Dihexa trial data in any peripheral neuropathy.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in alcohol brain fog, sober brain fog or alcohol-related brain damage (ARBD). Covers the ONS 2024 figure of 9,809 UK alcohol-specific deaths; the ~one-third ARBD prevalence among dependent drinkers and ARBD's ~10% share of young-onset dementia (Alcohol Change UK, Dementia UK); the 2025 “no safe level” UK Biobank brain-volume and Mendelian-randomisation dementia data; how chronic alcohol suppresses hippocampal BDNF and adult neurogenesis (with the 2026 Frontiers in Psychiatry proBDNF-cognition study); thiamine deficiency and Wernicke-Korsakoff syndrome (NICE CG100); cognitive and hippocampal recovery during abstinence; the 2025 semaglutide alcohol-use-disorder randomised trial and the GLP-1 link; the BDNF–HGF–c-Met synaptogenesis chain; the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure as a cautionary analogue; and why cutting down, thiamine and a medically supervised detox come first, not a peptide.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in statin-associated brain fog or statin-related cognitive symptoms. Covers the March 2026 NeuroToxicology study showing rosuvastatin disrupts human microglial viability, migration, phagocytosis and inflammatory signalling via the JAK-STAT pathway; the FDA's February 2012 statin label change adding “generally non-serious and reversible” memory loss and confusion; the 2025 systematic review and meta-analysis of ~7 million patients finding statin users have ~20% lower dementia and ~28–32% lower Alzheimer's risk; the brain-cholesterol-to-synapse mechanism (the brain holds ~20–25% of body cholesterol and makes it locally; Mauch et al. 2001 Science on glia-derived cholesterol and ApoE in synaptogenesis); the 2021 Molecular Brain simvastatin hippocampal LTP study; lipophilic (simvastatin, atorvastatin) vs hydrophilic (rosuvastatin, pravastatin) statins and blood-brain-barrier penetration; the nocebo effect and supervised re-challenge; NHS / NICE NG238 prescribing (5.3 million people in England, 2023/24); the cholesterol–BDNF–HGF–c-Met chain; the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure as a cautionary analogue; and why reviewing the statin with a GP comes first, not a peptide.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in magnesium deficiency brain fog or magnesium-related cognitive impairment. Covers the 2025 Frontiers in Nutrition randomised controlled trial of magnesium L–threonate (Magtein®, 2 g/day, 6 weeks) showing improved working and episodic memory, faster reaction time and better sleep in healthy adults; the 2023 UK Biobank study (Alateeq et al., ~6,000 adults) linking higher dietary magnesium to larger brain volumes and fewer white-matter lesions (a brain ~1 year younger by 55 at the highest intake); the foundational Slutsky 2010 Neuron “Enhancement of learning and memory by elevating brain magnesium” work on synaptic density; the NMDA-receptor magnesium gate, NMDA–excitotoxicity and the BDNF/TrkB plasticity mechanism; the measurement problem (only ~1% of body magnesium is in blood, so a normal serum result can hide a subclinical shortfall); UK reference nutrient intakes (300 mg men / 270 mg women) and the NHS 400 mg supplement upper level; magnesium L–threonate vs glycinate, citrate and oxide; the risk groups (poor diet, alcohol, type 2 diabetes, PPIs and diuretics, malabsorption, older age); the masking, diarrhoea and renal hypermagnesaemia risks; the BDNF–HGF–c-Met chain; the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure as a cautionary analogue; and the complete absence of any human Dihexa trial data in any magnesium-deficiency population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in vitamin D deficiency brain fog or vitamin-D-related cognitive impairment. Covers the April 2026 Neurology Open Access study (Mulligan et al.; University of Galway, Boston University & UT Health San Antonio; ~800 dementia-free adults, midlife bloods at ~age 39) linking higher midlife vitamin D to lower Alzheimer’s tau-PET burden a decade later; the classic Littlejohns 2014 Neurology cohort (51% higher dementia risk when deficient, 122% when severely deficient); the vitamin D receptor (VDR) and CREB–TrkB–BDNF mechanism, with the 2025 narrative review linking higher 25(OH)D to higher serum BDNF and better cognition; the genuinely mixed supplementation-trial evidence (2025 VitaMIND RCT in JAMDA; the Finnish Vitamin D Trial) showing benefit concentrates in real deficiency, not top-ups; the 2025 Frontiers dose-response dementia meta-analysis (~1.2% lower risk per 10 nmol/L); NHS/SACN 25(OH)D thresholds (<25 nmol/L deficient), the 10 µg (400 IU) autumn/winter recommendation and the 100 µg upper limit; UK winter and at-risk groups (darker skin, housebound/care home, obesity, coeliac/malabsorption, anticonvulsants, older age); the masking and hypercalcaemia risks; the BDNF–HGF–c-Met chain; the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure as a cautionary analogue; and the complete absence of any human Dihexa trial data in any vitamin-D-deficiency population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in iron deficiency, iron deficiency anaemia, low-ferritin brain fog or iron deficiency without anaemia. Covers the April 2025 University of Oklahoma study in Nutrients (17(5):745) showing non-anaemic perimenopausal women with “below expected” serum ferritin performed worse on memory, attention and cognition while brain iron stayed safe; the iron-dependent tyrosine hydroxylase / dopamine-synthesis and oligodendrocyte-myelination mechanisms (Journal of Neuroscience 2020; Annals of Medicine 2025); the animal evidence that iron deficiency downregulates hippocampal BDNF via chromatin remodelling at the Bdnf locus and alters neurotrophic-factor expression; the iron-deficiency-without-anaemia cognition literature in women of childbearing age, youths and children; the 2025 meta-analysis and AJCN trial showing iron supplementation improves cognition and fatigue in non-anaemic iron-deficient adults; NICE CKS and NHS ferritin thresholds (~30 µg/L) with CRP and transferrin-saturation interpretation; oral and intravenous iron (ferric carboxymaltose, PREFER, postpartum trials); the risk groups (heavy menstrual bleeding, pregnancy/postpartum, coeliac/malabsorption, vegetarian/vegan diets, GI blood loss); the gastrointestinal-blood-loss / bowel-cancer red-flag and the masking-a-serious-cause risk; the BDNF–HGF–c-Met chain; the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure as a cautionary clinical analogue; and the complete absence of any human Dihexa trial data in any iron-deficiency or anaemia population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in vitamin B12 deficiency brain fog, pernicious anaemia, hyperhomocysteinaemia or B12-related cognitive impairment. Covers the May 2026 UC San Francisco study in Annals of Neurology (Beaudry-Richard, Abdelhak & Green; 231 healthy BrANCH-study adults, mean age 71) showing that lower biologically active B12 — despite total B12 averaging 414.8 pmol/L, far above the 148 pmol/L deficiency cut-off — was associated with slower processing speed, delayed visual responses and a higher volume of white-matter lesions on MRI; NICE NG239 (2024) listing “brain fog” among recognised B12-deficiency symptoms and the ≤2-week to 3-month recovery expectation; the total-B12 vs active-B12 (holotranscobalamin), methylmalonic acid (MMA) and homocysteine testing distinction; the homocysteine–SAM:SAH–DNA-hypomethylation mechanism that suppresses hippocampal neurotrophins (TrkB, VEGF, EGF), restrains neurogenesis and disrupts the blood-brain barrier (including the Cav1.2 hypomethylation work); the VITACOG trial (Smith 2010 PLOS One; Douaud 2013 PNAS) showing homocysteine-lowering B vitamins slowed grey-matter atrophy ~30% in raised-homocysteine MCI; the 2025 Nutrition Reviews B-vitamin cognition meta-analysis and 2025 Mendelian-randomisation null for total B12; the at-risk groups (pernicious anaemia / autoimmune gastritis, long-term metformin and PPIs, coeliac and malabsorption, vegan/vegetarian diets, older age); the folic-acid masking trap and subacute combined degeneration risk; B12 replacement (injections vs oral) as the only evidence-based treatment; the BDNF–HGF–c-Met chain and cerebrovascular-angiogenesis angle; the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure as a cautionary clinical analogue; and the complete absence of any human Dihexa trial data in any B12-deficiency, pernicious-anaemia or hyperhomocysteinaemia population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in “baby brain”, “mum brain”, pregnancy brain fog or postpartum cognitive symptoms. Covers the Davies 2018 Medical Journal of Australia meta-analysis (20 studies, 709 pregnant vs 521 non-pregnant women) showing measurably poorer general cognition, memory and executive function in pregnancy, most marked in the third trimester; the Hoekzema 2017 Nature Neuroscience finding that pregnancy reduces gray matter in social-cognition (“theory of mind”) regions for at least two years as adaptive synaptic-pruning-like specialisation, with hippocampal recovery tracking cognitive recovery; the Pritschet, Jacobs & Chrastil 2024 Nature Neuroscience precision-imaging study mapping the maternal brain across 26 scans from pre-conception to two years postpartum (cortical thinning, mid-gestation white-matter rise, partial rebound); the Maternal Brain Project; the postpartum estradiol and progesterone crash and the estrogen–BDNF–TrkB coupling; the allopregnanolone / GABA-A neurosteroid collapse underpinning postnatal depression and the brexanolone (Zulresso, 2019) and zuranolone (Zurzuvae, FDA August 2023) treatments; the dominant treatable drivers (sleep fragmentation, postpartum thyroiditis, iron-deficiency anaemia, B12/folate, and postnatal depression/anxiety); UK scale via ONS (567,708 live births in England in 2024, TFR 1.41) and the RCPsych July 2025 estimate of 56,000–85,000 mothers with postnatal depression and perinatal mental illness affecting up to 1 in 5; the BDNF–HGF–c-Met chain; the absolute contraindication in pregnancy and breastfeeding given HGF/c-Met’s essential role in trophoblast invasion, placentation and fetal organogenesis (embryonic-lethal when absent) and the total absence of developmental safety data; the fosgonimeton (ATH-1017) LIFT-AD Phase 3 failure as a cautionary clinical analogue; and the complete absence of any human Dihexa trial data in any perinatal population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in coeliac disease, gluten-related brain fog, non-coeliac gluten sensitivity (NCGS), gluten ataxia or gluten encephalopathy. Covers Coeliac UK’s estimate that ~1 in 100 Britons have coeliac disease but only ~36% are diagnosed (~500,000 undiagnosed); the Yelland 2017 Journal of Gastroenterology and Hepatology review formalising gluten-induced cognitive impairment (“brain fog”); the Lichtwark 2014 Alimentary Pharmacology & Therapeutics finding that cognition improves over 12 months on a gluten-free diet in parallel with intestinal mucosal healing (Marsh score) and falling tissue transglutaminase antibodies; the Addolorato 2004 American Journal of Medicine SPECT study showing regional cerebral hypoperfusion in 73% (11/15) of untreated coeliac patients that reversed on a gluten-free diet; the Sheffield gluten-neurology tradition led by Marios Hadjivassiliou, transglutaminase-6 (TG6) antibodies and the 2024 Brain Communications gluten-ataxia / microglial-activation paper; the 2020 Croall PLOS One NCGS brain-fog MRI pilot; the nutritional-malabsorption drivers (iron / ferritin, B12, folate, vitamin D, copper) as the most correctable cause; the systemic-inflammation and gut-brain-axis components; the transglutaminase-6 neural-autoimmunity mechanism; the downstream hippocampal BDNF / HGF–c-Met chain and the unusual cerebrovascular-angiogenesis angle; the strict lifelong gluten-free diet as the only evidence-based, disease-modifying treatment with dietitian and Coeliac UK support; NICE NG20 and the anticipated no-biopsy serology-pathway update; the emerging gluten-free interleukin-2 (IL-2) release diagnostic blood test; the enteropathy-associated T-cell lymphoma (EATL) / small-bowel adenocarcinoma c-Met oncology concern; the masking-a-treatable-cause directionality problem; the fosgonimeton (ATH-1017) Athira LIFT-AD Phase 3 failure as a cautionary clinical analogue; and the complete absence of any human Dihexa trial data in any coeliac, gluten-sensitivity or gluten-related neurological population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in postural orthostatic tachycardia syndrome (PoTS), dysautonomia, orthostatic intolerance or autonomic-related cognitive dysfunction. Covers PoTS UK’s estimate of several hundred thousand affected UK adults (80–85% female, typical onset 15–50 years, frequent 4–7 year diagnostic delay); the Dulal, Grubb & Maraey 2025 European Heart Journal >65 million-record analysis reporting a ~14-fold rise in PoTS incidence post-pandemic; the January 2025 Seeley et al. Scientific Reports brain SPECT paper from the University of Adelaide’s Australian Dysautonomia and Arrhythmia Research Collaborative documenting abnormal regional cerebral perfusion in PoTS patients with cognitive dysfunction; Stewart 2020 Frontiers in Neuroscience and JAHA cerebral blood flow under sustained cognitive stress; the Ross 2013 Clinical Autonomic Research 138-patient brain fog characterisation (forgetfulness 91%, difficulty thinking 89%, difficulty focusing 88%); Wells 2017 Autonomic Neuroscience cognitive/psychological review; the 2022 brain fog neuropathic PoTS and autonomic hyperarousal paper; the POTSKog 2023 Clinical Autonomic Research body position study; the 2025 Larsen et al. Circulation: Arrhythmia and Electrophysiology finding that ~31% of highly symptomatic Long COVID patients meet PoTS criteria; the LISTEN study in JACC: Advances (2025); the October 2025 JACC quantitative autonomic testing Long COVID paper; the 2005 Shibao et al. Hypertension Vanderbilt mast cell–noradrenaline axis paper underpinning MCAS-PoTS overlap; the neuropathic / hyperadrenergic / hypovolaemic / MCAS-overlap / hEDS-overlap subtype framework; the 2015 Heart Rhythm Society Expert Consensus Statement (Sheldon) on diagnosis and treatment of PoTS / IST / vasovagal syncope; the 2018 ESC syncope guidelines (Brignole); the absence of a NICE PoTS guideline; the October 2024 Westminster Hall debate led by Cat Smith MP (Lancaster & Wyre) and the PoTS UK Parliamentary Campaign 2025 with Sharon Hodgson MP and the Department of Health and Social Care; the ME Association PoTS survey results; the Bristol BNSSG ICB Remedy pathway; the Chest Heart & Stroke Scotland PoTS factsheet; ivabradine (NICE TA679-licensed for chronic heart failure / angina) used off-licence under specialist supervision; propranolol, bisoprolol, midodrine, fludrocortisone and pyridostigmine; the Levine / CHOP modified Dallas graded recumbent-first reconditioning protocol (recumbent rowing, cycling, swimming, supine resistance training over 3–8 months); salt 8–10 g/day and 2–3 L fluids; class 2 (20–30 mmHg) compression hosiery and abdominal binders; head-of-bed elevation; treatable-imitator screening (ferritin, B12, folate, vitamin D, TSH, anti-ganglionic AChR antibody in atypical presentations); secondary PoTS rule-outs (diabetic autonomic neuropathy, paraneoplastic syndromes, amyloid neuropathy); the cerebral hypoperfusion / BDNF / HGF–c-Met chain and the unusual HGF/c-Met cerebrovascular angiogenesis angle; the directionality risk of synaptogenesis on top of unresolved autonomic dysfunction and the hyperadrenergic noradrenergic destabilisation theoretical risk; the fosgonimeton (ATH-1017) Athira LIFT-AD Phase 3 failure as a cautionary clinical analogue; and the complete absence of any human Dihexa trial data in any PoTS, dysautonomia, orthostatic intolerance or autonomic disorder population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in acute Lyme disease, Lyme neuroborreliosis, Post-Treatment Lyme Disease Syndrome (PTLDS), Lyme encephalopathy, ongoing symptoms after treated Lyme, "chronic Lyme" or any tick-borne illness population. Covers Lyme as the most common UK vector-borne illness on the Chief Medical Officer's 2025 infections report (Professor Sir Chris Whitty) with ~1,500 laboratory-confirmed cases in England and Wales annually plus 1,000-4,000 additional clinical cases; the Cairns 2019 BMJ Open CPRD population-based cohort showing UK incidence rising from 2.55 to 9.33 per 100,000 person-years between 2000 and 2018; the Geebelen 2022 PLOS One UK incidence and post-Lyme fatigue association; the geographic concentration in Scottish Highlands, southern England, the New Forest, Cumbria, Exmoor and the Lake District; the UK Centre for Ecology & Hydrology £2 million tick-borne disease climate-modelling programme and the May 2026 UKHSA tick-borne encephalitis virus (TBEV) UK update; the April 2025 Jutras et al. Science Translational Medicine paper demonstrating persistent Borrelia burgdorferi peptidoglycan accumulating in discrete tissues and driving systemic inflammation consistent with chronic illness; the 2018 Greenmyer et al. Frontiers in Microbiology primary-human-microglia / B. burgdorferi CCL2/CCL3/CCL5/CXCL10/IL-6/TNF-α chemokine and cytokine upregulation paper; the 2018 Coughlin Johns Hopkins multimodal-neuroimaging PTLDS paper showing TSPO-PET microglial activation and white-matter integrity change correlating with cognitive performance; the Klempner 2001 NEJM repeat IV antibiotic RCT and the Fallon 2008 Neurology ceftriaxone Lyme-encephalopathy RCT history and the 2026 Devoto et al. Nature Scientific Reports open-label psilocybin PTLD pilot study (20 participants, 8-week intervention); the 23 March 2026 Pfizer / Valneva VLA15 (PF-07307405 / LB6V) multivalent OspA Lyme vaccine Phase 3 VALOR positive readout (73.2% efficacy reducing confirmed Lyme cases from 28 days post-dose 4, 74.8% from 1-day post-dose 4, no safety concerns at time of analysis, ~9,400 participants aged 5+, BLA / MAA submission planned 2026, MHRA / JCVI UK conversation pending); NICE NG95 (April 2018; March 2026 implementation update) doxycycline 100mg twice daily for 21 days first-line in non-pregnant adults, amoxicillin or ceftriaxone in specific situations, two-tier ELISA C6-VlsE plus immunoblot serology, erythema migrans alone sufficient for treatment, NICE position against routine prolonged or repeat antibiotic regimens for ongoing symptoms and against "chronic Lyme" as a free-standing diagnosis; the EFNS European Federation of Neurological Societies neuroborreliosis guideline; the European Bannwarth syndrome (B. garinii-driven painful radiculitis, cranial neuritis frequently bilateral facial palsy, lymphocytic meningitis) versus North American isolated cranial neuropathy phenotype; CSF intrathecal anti-Borrelia antibody index, CXCL13, lymphocytic pleocytosis; the 10-20% PTLDS incidence after treated Lyme and up to 90% cognitive symptom prevalence in PTLDS cohorts; the IDSA / AAN / ACR North American PTLDS case definition; the anti-neuronal antibody / molecular mimicry autoimmune component; the BDNF / TrkB / hippocampal LTP suppression mechanism; the blood-brain barrier disruption and cerebral perfusion change; the patient-facing UK ecosystem (Lyme Disease Action, Lyme Disease UK, Caudwell Lyme Co, the NHS Lyme disease pages, the UKHSA Lyme dashboard); tick-bite prevention (DEET 20-50% or icaridin repellent, fine-tipped tweezers removal within 24 hours, prompt GP review for erythema migrans within 30 days); the treatable-imitator screening profile (ferritin, B12, folate, vitamin D, TSH, coeliac antibodies, fasting glucose / HbA1c, OSA, depression); the directionality risk that pharmacological synaptogenesis on top of unresolved B. burgdorferi-peptidoglycan-driven innate immune activation may not produce sustained cognitive benefit; the c-Met-immune-cell-migration interaction concern; the general c-Met / oncology baseline concern; the fosgonimeton (ATH-1017) Athira LIFT-AD Alzheimer Phase 3 failure (a population whose biology overlaps with PTLDS at the inflammation-plasticity interface) and the complete absence of any human Dihexa trial data in any Lyme, neuroborreliosis, PTLDS, post-infection chronic illness or tick-borne disease population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in Hashimoto's thyroiditis, primary hypothyroidism, subclinical hypothyroidism, autoimmune thyroid disease, treated hypothyroidism with residual brain fog, euthyroid antibody-positive Hashimoto's, post-partum thyroiditis or any thyroid-related cognitive symptom. Covers Hashimoto's as the most common autoimmune disease in iodine-sufficient countries (Mavroudis 2025 Medicina scoping review: 4.8-25.8% in women, 0.9-7.9% in men, female-to-male ratio 2-7x; 2-3% of UK adults treated for hypothyroidism with a further 4-10% in the subclinical range); the substantial brain fog burden (memory disorders ~24%, slow thinking ~22%, fatigue ~18%; >95% of patients list forgetfulness, fatigue, sleepiness and lack of focus among core symptoms; ~10% of levothyroxine-treated patients have persistent brain fog despite normal TSH); the October 2025 NICE NG145 exceptional surveillance decision retaining levothyroxine as first-line and declining to update the recommendation against routine liothyronine (T3) alone or in combination, with the research recommendation around DIO2 polymorphism and persistent symptoms remaining open; the NHS England Regional Medicines Optimisation Committee guidance constraining new T3 initiation; the T3-BDNF axis in the hippocampus — the 2016 Endocrinology Camilo paper on mild developmental thyroid hormone insufficiency compromising activity-dependent neuroplasticity into adulthood; the 2021 Sui PMC paper on absence of thyroid hormone causing delayed dendritic arborisation in primary hippocampal neurons through insufficient BDNF expression; the 2021 Leyhe Scientific Reports Hashimoto's thyroiditis event-related potentials (ERP) and magnetic resonance spectroscopy (MRS) study showing prolonged N200 and P300 latencies, reduced P300 amplitude and cognitive correlation; the 2018 Krysiak Medicine (Baltimore) low vitamin D and cognitive impairment in Hashimoto's association; the DIO2 Thr92Ala deiodinase polymorphism and brain-T3 question; Hashimoto's encephalopathy / steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) and the 2025 Biomedicines and 2025 Frontiers in Psychiatry reviews with the >2-year persistent cognitive deficit picture despite corticosteroid therapy; the absorption pitfalls (food, coffee, calcium, iron, PPIs, MHRA brand-consistency considerations); the c-Met / papillary thyroid cancer oncology concern in a population with elevated thyroid-nodule risk; British Thyroid Foundation (BTF), Thyroid UK, British Thyroid Association (BTA) and NHS underactive thyroid pages as UK patient-facing resources; co-existing coeliac disease (~5%), vitamin D deficiency, iron / ferritin / B12 / folate deficiencies as treatable imitators; obstructive sleep apnoea overlap in hypothyroidism; perimenopause / menopause overlap as a midlife confounder; the fosgonimeton (ATH-1017) Athira LIFT-AD Phase 3 failure as a cautionary clinical analogue; the BDNF-synaptogenesis Benoist 2014 JPET Dihexa pharmacology paper; and the complete absence of any human Dihexa trial data in any thyroid, autoimmune thyroid, hypothyroid, Hashimoto's, Graves' or thyroid-related cognitive population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in endometriosis, endo brain fog, chronic pelvic pain, dysmenorrhea or adenomyosis-associated cognitive dysfunction. Covers the ~1.5 million UK women living with endometriosis (~10% of women of reproductive age on Endometriosis UK / NHS England denominators), the 9 years 4 months UK average diagnostic delay (Endometriosis UK 2024 survey of 4,371 patients; 47% visited the GP 10+ times before diagnosis; 78% reported being dismissed), the November 2025 Lancet Obstetrics, Gynaecology & Women’s Health 'The overlooked symptom in endometriosis: brain fog' commentary by Mahony, Saunders, Whitaker and Horne at the University of Edinburgh EXPPECT centre, the April 2025 Horn / Sherman / Pehlivan Macquarie / Sydney Journal of Health Psychology FACT-Cog survey of 1,239 individuals reporting ~80% perceived cognitive impairment, the March 2025 NICE TA1057 approval of Ryeqo (relugolix-estradiol-norethisterone, Gedeon Richter) as the first daily oral combination GnRH-antagonist pill for long-term endometriosis symptom management on the NHS with ~1,000 women per year eligible, the April 2024 NICE NG73 endometriosis diagnosis and management update, the April 2026 renewed Women’s Health Strategy for England with 117 action points and explicit pledge to "eliminate the diagnostic odyssey", the 5 March 2026 Hansard Westminster Hall debate on Women’s Health Strategy: Endometriosis and Fibroids, the February 2026 Endometriosis UK 'State of Endometriosis Care' roadmap, the 2025 Frontiers in Immunology JAK-STAT / mast cell activation neuroinflammation paper, the 2023 Journal of Neuroinflammation Greaves group mouse-model CNS-wide glial activation paper showing microglial activation across thalamus, hippocampus and cortex, the Wu Hu Liang 2022 BMC Women’s Health paper documenting elevated BDNF and TrkB correlating with dysmenorrhea severity, the long-standing BDNF-elevated-in-peritoneal-fluid-and-plasma literature (Hu 2018; Wu 2014), the central-sensitisation hippocampal-amygdala-prefrontal-cortex network rewiring story, the ~3x migraine comorbidity, ~50% IBS overlap, ~25% fibromyalgia overlap, ~50% depression / anxiety burden, the ~80% adenomyosis co-existence, the BSGE-accredited endometriosis centres pathway, the ESHRE 2022 Becker / Bokor guideline, the RCOG framework, the Edinburgh EXPPECT (Andrew Horne, Philippa Saunders, Lucy Whitaker), Oxford CaRe (Krina Zondervan, Christian Becker) and Birmingham academic ecosystem, dienogest (Visanne), goserelin (Zoladex), leuprolide (Prostap), linzagolix (Yselty), elagolix (Orilissa), Mirena IUS, the central directionality risk that a synaptogenic HGF/c-Met peptide augmenting BDNF/TrkB-dependent plasticity could plausibly consolidate rather than weaken the very central-sensitisation pain-and-cognition pathology driving endometriosis brain fog, the additional HGF/c-Met ectopic lesion proliferation and angiogenesis concern, Endometriosis UK (helpline 0808 808 2227), The Endometriosis Foundation, the Pelvic Pain Support Network, the fosgonimeton (ATH-1017) Athira LIFT-AD Phase 3 failure and complete absence of any endometriosis testing, and the complete absence of any human Dihexa trial data in any endometriosis, adenomyosis, chronic pelvic pain or dysmenorrhea population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in systemic lupus erythematosus (SLE), lupus brain fog, neuropsychiatric SLE (NPSLE), lupus nephritis or cutaneous lupus populations. Covers the ~69,000-100,000 UK lupus population on the 2024 CPRD Yen / Singh analysis (point prevalence 21.4 per 100,000 in 1990 rising to 107.14 per 100,000 by 2020, incidence 5.47 per 100,000 person-years, 9:1 female:male ratio, higher prevalence and severity in British African / Caribbean and South Asian women); the Hanly pooled-prevalence meta-analysis showing 38% (95% CI 33-43%) measurable cognitive impairment and ~80% subjective brain fog; the 1999 ACR NPSLE case definition (19 syndromes: 12 central, 7 peripheral); the Diamond / DeGiorgio / Volpe 2001 Nature Medicine paper showing anti-dsDNA cross-reactivity with the NR2A/B NMDA-receptor pentapeptide D-W-E-Y-S; the Faust 2010 PNAS paper demonstrating BBB-permeability-dependent DNRAb-mediated hippocampal CA1 and lateral amygdala cognitive damage rescued by memantine; the 2021 Mougiakakos / Mackensen / Schett NEJM first CD19 CAR-T cell therapy refractory SLE patient and the 2022 Nature Medicine five-patient cohort with complete drug-free remission; the EULAR 2024 expanded 12-patient SLE / lupus nephritis cohort with 11 of 12 patients in drug-free remission at mean 458-day follow-up; the September 2025 Journal of Rheumatology preliminary quality-of-life and health-economic analysis of 8 patients followed >2 years; the 30 September 2024 CHMP positive recommendation and Q4 2024 EU approval of anifrolumab (Saphnelo, AstraZeneca) subcutaneous self-administration prefilled-pen formulation based on TULIP-SC; the November 2025 Bristol Myers Squibb late-breaking ACR Convergence Sotyktu (deucravacitinib) PAISLEY-SLE 4-year safety and efficacy integrated analysis with the POETYK SLE-1 (NCT05617677) and POETYK SLE-2 (NCT05620407) Phase 3 trials enrolling approximately 980 participants total for 60 weeks; the 2025 Biogen litifilimab (BIIB059) anti-BDCA2 plasmacytoid dendritic cell programme advancing to Phase 3 TOPAZ-1 SLE, TOPAZ-2 SLE and AMETHYST CLE; NICE TA882 voclosporin (Lupkynis) with mycophenolate mofetil for lupus nephritis (April 2023, AURORA-1 / AURORA-2); NICE TA397 belimumab IV (Benlysta, GSK, June 2016) and NICE TA752 belimumab SC (2021) anti-BAFF/BLyS axis; the terminated NICE TA793 anifrolumab UK appraisal due to no AstraZeneca evidence submission; the 2018 BSR systemic lupus erythematosus guideline (Gordon et al., Rheumatology) and 2024 BSR scope expansion to children, young people and adults; the 2019 EULAR/ACR weighted classification criteria (10-point system with ANA ≥1:80 entry); the SLE autoantibody landscape (anti-dsDNA, anti-Sm, anti-Ro/SSA, anti-La/SSB, anti-U1RNP, ribosomal-P [Bonfa 1987 NEJM lupus psychosis], antiphospholipid lupus anticoagulant / anti-cardiolipin / anti-beta-2-GPI driving secondary APS); the Watson 1983 PNAS lupus brain-reactive antibodies foundational paper; the type I interferon signature (IFN-alpha/beta) plasmacytoid dendritic cell pDC autoamplification loop; the BAFF / BLyS axis B-cell hyperactivity; the JAK/STAT/TYK2 signalling cascade; complement C3 / C4 hypocomplementaemia; the 2024 S100A8/A9 and MMP-9 cognitive-impairment biomarker paper (PMC10851148); the multiple commercial CD19 CAR-T programmes (Kyverna KYV-101 KYSA-1 / KYSA-3, Cabaletta CABA-201 RESET-SLE, Cartesian Descartes-08 BCMA mRNA, BMS bbT369 CD19/CD20 dual, AstraZeneca C-CAR168 RoseliCar CD19/BCMA dual); the conventional pharmacology (hydroxychloroquine cornerstone with Royal College of Ophthalmologists retinopathy screening, mycophenolate mofetil, azathioprine with TPMT/NUDT15 testing, methotrexate, low-dose Euro-Lupus pulse cyclophosphamide, rituximab off-label NHS England access protocol, prednisolone tapered to lowest effective dose); the SLE comorbidity cluster (fibromyalgia 22-25%, Sjogren's secondary 15-20%, antiphospholipid syndrome 30-40%, MCTD U1RNP, hEDS, depression 30-70%, anxiety, sleep disturbance, Long COVID); the conflicting BDNF-in-SLE serum literature (Petri 2021 Clinical Rheumatology 111-patient cohort decreased BDNF but no NPSLE cognitive correlation vs Eilat 2013 elevated BDNF/NGF); the Yamamoto 1996 elevated HGF in active SLE and the Niwa 1999 Nephrology Dialysis Transplantation elevated urinary HGF in lupus nephritis renal-protective compensation; the central directionality risk that a synaptogenic HGF/c-Met-activating peptide that augments NMDA-dependent synaptic plasticity could amplify rather than relieve the DNRAb-driven cognitive damage that memantine reverses; the c-Met oncogenicity / lymphoma background risk concern in SLE patients; the HGF/c-Met blood-brain-barrier and angiogenic protective biology (Wright & Harding 2015); the EG-501 NPSLE Phase 2 study (NCT07281105) and LUPUS Brain transcranial alternating current stimulation (tACS) NCT04141046; UK tertiary lupus services at UCLH Centre for Rheumatology, Louise Coote Lupus Unit (Guy's and St Thomas'), Manchester / Salford, Bath / Royal United Hospital, Birmingham, Edinburgh, Glasgow and Belfast; LUPUS UK (helpline 01708 731251, Romford), The Lupus Trust, Lupus Research Alliance, Versus Arthritis; the fosgonimeton (ATH-1017) Athira LIFT-AD Phase 3 failure and complete absence of any lupus testing; and the complete absence of any human Dihexa trial data in any systemic lupus erythematosus, cutaneous lupus, lupus nephritis or NPSLE population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in autism spectrum disorder (ASD), Asperger’s, PDD-NOS, Rett syndrome, Fragile X syndrome, Phelan-McDermid syndrome, Angelman syndrome, tuberous sclerosis or any neurodevelopmental population. Covers the ~700,000 UK autistic population (~1% prevalence) and the 2023 BJGP estimate of 150,000-500,000 adults aged 20-49 likely undiagnosed; the March 2026 NHS England Autism Statistics reporting 270,701 patients with an open referral and 89.7% breaching the NICE NG142 13-week standard; the 12 December 2025 FDA approval of DAYBUE STIX (trofinetide oral solution powder formulation, Acadia Pharmaceuticals / Neuren) for Rett syndrome aged 2+, building on the March 2023 LAVENDER Phase 3 approval; the 10 March 2026 FDA approval of leucovorin (folinic acid) only for cerebral folate deficiency in confirmed FOLR1 variant carriers and the explicit refusal to extend to broader autism following the January 2026 retraction of the Panda et al. European Journal of Pediatrics leucovorin-autism RCT; the 2026 NEJM Perspective on cerebral folate deficiency, autism and leucovorin; the January 2026 brain-wide [18F]FPEB PET study reporting 16-23% lower mGluR5 availability across cortical regions in autistic adults (left frontal pole -23%, left cingulate -23%, frontal lobe -19%, temporal lobe -19%, cerebellum -19%, fusiform gyrus -18%); the Carbonell-Roig & Aviles-Olmos 2026 Journal of Neural Transmission mGluR5 review; the Campbell 2006 PNAS family-based association of the rs1858830 MET promoter C-allele with autism in 204 families replicated in 539 families (combined p = 5×10−6) — the single most replicated functional autism candidate-gene variant and a direct mechanistic anchor to Dihexa’s HGF/c-Met pharmacology; the Campbell 2007 Annals of Neurology postmortem ASD cortex MET protein reduction; the Eagleson & Levitt 2015 Molecular Psychiatry MET-signalling forebrain glutamatergic circuit work; the Heuer 2011 Translational Psychiatry MET-maternal-autoantibody / cytokine interaction; the Volk 2014 Epidemiology MET-air-pollution gene-environment interaction; the Hedrick 2012 NeuroImage MET-cortical-thickness imaging genetics finding; the BDNF Val66Met (rs6265) polymorphism literature in autism (Hashimoto / Sakai 2016 meta-analysis) and the BDNF directionality paradox (Garcia-Penas, Connolly, Nelson 2003 Pediatrics showing elevated rather than depleted serum BDNF in autistic children and even newborns later diagnosed); NICE NG142 (September 2017, updated 2021) recognition / referral / diagnosis in under-19s, NICE NG87 (August 2013, updated 2021) management / support, NICE CG142 (June 2012, updated 2021) adult diagnosis and management, the UK Autism Act 2009 and Down Syndrome and Autism Act 2022, the National Autism Strategy 2021-2026, Building the Right Support, the NHS England national framework for all-age autism assessment pathways, the Right-to-Choose pathway via Psychiatry-UK / ProblemShared / Clinical Partners; the diagnostic ecosystem (M-CHAT-R/F, SCQ, AQ-10, ADOS-2, ADI-R, DISCO, 3Di); the National Autistic Society (NAS, 0808 800 4104), Autistica, Ambitious about Autism, Mencap, IPSEA, SFARI Gene database (1,000+ genes), SPARK (Simons Powering Autism Research, 100,000+ cohort) and MSSNG (Autism Speaks, 10,000+ genomes); the comorbidity landscape (ADHD 50-70%, anxiety 40-50%, depression 25-40%, OCD, epilepsy 20-30%, intellectual disability 30-50%, sleep disorders 50-80%, hEDS / hypermobility 22% Cederlof 2016, gender dysphoria 6-26% Warrier 2020); syndromic autism (Fragile X FMR1 ~1 in 4,000 males; Rett syndrome MECP2 ~1 in 10,000-15,000 girls; Angelman UBE3A 15q11-13; Phelan-McDermid SHANK3 22q13 ~1 in 8,000-15,000; tuberous sclerosis TSC1/TSC2 ~50% ASD; Down syndrome trisomy 21 16-19% ASD; CHARGE CHD7; Smith-Magenis RAI1; Williams 7q11.23 deletion ELN); the genetic architecture (Iossifov / Sanders 2014 Nature de novo, Grove / Børglum 2019 Nature Genetics polygenic, Tick / Bolton / Happé 2016 Mol Psychiatry 80-90% heritability); the autism drug-development graveyard (bumetanide SIGN1 / SIGN2 Servier 2021, balovaptan Roche V1A 2020, arbaclofen STX209 Seaside Therapeutics, mavoglurant AFQ056 / basimglurant Roche Fragile X 2014, intranasal oxytocin Sikich 2021 NEJM, CBD Aran 2021 Frontiers, NAC Hardan 2012, sulforaphane Singh-Talalay 2014 PNAS, FMT Kang 2017 / 2019); the central directionality risk that a synaptogenic HGF/c-Met-activating BDNF-elevating peptide given during sensitive-period plasticity could plausibly destabilise rather than rescue atypical cortical wiring (sensory hyper-responsivity reinforcement, RRB consolidation, anxiety amplification, E/I imbalance worsening); the HGF/c-Met synaptogenic mechanism of Dihexa (Benoist 2014 JPET; Wright & Harding 2015); fosgonimeton (ATH-1017) Athira LIFT-AD Phase 3 failure and the complete absence of any autism / Rett / Fragile X / neurodevelopmental testing; the safeguarding considerations under the Children Act 1989 / Working Together to Safeguard Children for the administration of unapproved peptides to children; and the complete absence of any human Dihexa trial data in any autism, ASD, Asperger’s, PDD-NOS, Rett syndrome, Fragile X syndrome or related neurodevelopmental population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in migraine, chronic migraine, hemiplegic migraine, vestibular migraine, medication-overuse headache or cluster-headache populations. Covers the ~10 million UK adults with migraine on Migraine Trust 2026 figures (~1 in 7 Britons, ~1 million chronic migraine, ~190,000 attacks per day, women three times more likely than men, 25-43 million lost workdays annually and a £6-10 billion economic cost), the 15 May 2024 NICE Technology Appraisal TA973 atogepant (Aquipta, AbbVie) 60mg once-daily oral CGRP-receptor antagonist approval reaching an estimated 170,000 England-eligible patients, NICE TA919 rimegepant acute and TA906 rimegepant prevention (Pfizer / Biohaven Vydura / Nurtec ODT), the CGRP monoclonal antibody pathway anchored by TA682 erenumab (Aimovig), TA659 galcanezumab (Emgality), TA764 fremanezumab (Ajovy) and TA871 eptinezumab (Vyepti), NICE TA260 onabotulinumtoxinA (Botox) for chronic migraine under the PREEMPT 31-site / 155-unit / 12-week protocol, the 2025 Fernandes & Gil-Gouveia Cephalalgia mechanistic review of migraine-related cognitive dysfunction, the 2025 Medical Research Archives chronic migraine accelerated brain ageing and hippocampal atrophy review, the 2024 Hippocampal Connectivity Dynamics resting-state fMRI volumetric paper (PMID 39675538), the 2022 P2X7R/NLRP3 pyroptosis and neuroinflammation migraine cognitive impairment mouse model (PMC9250730), the Tanure 2010 Headache pilot study finding serum BDNF elevated during migraine attacks (PMID 20556464), the cortical spreading depression (CSD) and trigeminovascular pathophysiology with CGRP, PACAP-38 and glutamatergic hyperexcitability biology, the BDNF Val66Met (rs6265) polymorphism in migraine susceptibility, NICE NG150 (September 2021) headache assessment in over-12s, the BASH British Association for the Study of Headache UK guideline, the Migraine Trust, National Migraine Centre, Brain Research UK, OUCH UK and Hemiplegic Migraine Association UK patient ecosystem, lasmiditan (Reyvow) 5HT1F ditan, zavegepant (Zavzpret) intranasal CGRP, ubrogepant (Ubrelvy), GammaCore nVNS, Cefaly external trigeminal neurostimulator and Nerivio remote electrical neuromodulation device pathways, the conventional preventative armamentarium (propranolol, amitriptyline, topiramate, candesartan, sodium valproate under the MHRA Pregnancy Prevention Programme), the migraine-with-aura ischaemic stroke risk axis, the patent foramen ovale (PFO) closure MIST / PRIMA / PREMIUM / CLOSURE-3 trial controversy, the CAMERA-1 and CAMERA-2 white-matter-hyperintensity studies, the medication-overuse headache (MOH) NICE NG150 management framework, vestibular migraine (Lempert / Society Barany 2012 criteria), hemiplegic migraine (CACNA1A, ATP1A2, SCN1A), cluster headache (oxygen, sumatriptan SC, verapamil, galcanezumab FDA 2019, GammaCore), the BDNF directionality paradox and CSD-threshold-lowering / central-sensitisation-consolidation risk for any synaptogenic peptide claim, the HGF/c-Met synaptogenic mechanism of Dihexa (Benoist 2014 JPET; Wright & Harding 2015), fosgonimeton (ATH-1017) Athira LIFT-AD Phase 3 failure and the complete absence of any human Dihexa trial data in any migraine population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS), post-exertional malaise (PEM), post-viral fatigue syndrome (PVFS), post-infectious ME/CFS, ME/CFS brain fog, Long COVID with ME/CFS overlap or any post-exertional symptom exacerbation (PESE) population. Covers the ~250,000 UK adult and paediatric ME/CFS population (75-85% women, ~25% severely or very severely affected on Action for ME / ME Association / 25% ME Group denominators); the 6 August 2025 DecodeME genome-wide association study preprint (Ponting, Edinburgh, MRC Human Genetics Unit, Action for ME) reporting eight genome-wide significant loci across 15,579 European-ancestry cases versus 259,909 controls with lead genes RABGAP1L, BTN2A2, OLFM4, FBXL4 and CA10 converging on viral defence, innate immunity and mitochondrial function with a striking female-only sex-specific signal (three of six primary loci replicated in females, none in males); the 22 July 2025 DHSC final UK ME/CFS Delivery Plan "My Full Reality" with the NIHR application development award scheme, MRC PRIME infrastructure programme and UKRI ME/CFS Priority Area; the 21 February 2024 NIH Walitt deep-phenotyping Nature Communications paper (PMC10881493) reframing post-infectious ME/CFS as a central rather than peripheral disorder with altered effort preference on the EEfRT task and central catechol dysregulation; the April 2025 ME Association £132,000 investment in the UBC double-blind low-dose naltrexone (LDN) trial led by Dr Luis Nacul in post-COVID fatigue syndrome with ME/CFS overlap (NCT05430152); the Nakatomi 2014 11C-(R)-PK11195 PET microglial activation finding in cingulate, hippocampus, thalamus, midbrain and pons; the August 2025 Younger UAB Birmingham MRI thermometry whole-brain neuroinflammation study; the Polli 2020 Arthritis & Rheumatology paper showing BDNF hypomethylation and elevated peripheral BDNF in CFS-with-fibromyalgia with symptom correlation; the October 2024 Maeve Boothby O'Neill Prevention of Future Deaths (Regulation 28) report and the absence of NHS England commissioned severe-ME inpatient provision; NICE NG206 (October 2021) removing graded exercise therapy and confirming post-exertional malaise as a required diagnostic feature; the Wong & Weitzer 2021 Medicina systematic review showing 25 of 29 ME/CFS symptoms in Long COVID populations, the Dehlia & Guthridge 2024 Journal of Infection meta-analysis estimating ~51% of Long COVID patients meet ME/CFS criteria, and the January 2025 RECOVER Vernon analysis showing 4.5% post-COVID ME/CFS prevalence (15x baseline); the Castro-Marrero 2021 coenzyme Q10 plus NADH RCT and 2024 mitochondrial review, the Cash & Kaufmann 2024 RESTORE-ME oxaloacetate RCT and REGAIN trial, the AIM ImmunoTech rintatolimod (Ampligen) AMP-518 Long COVID readout, the Berlin Cures BC 007 Phase 2 Long COVID failure November 2024, the David Systrom pyridostigmine (Mestinon) preload failure POTS programme, the low-dose aripiprazole observational case series; the ME/CFS comorbidity cluster (fibromyalgia, POTS, MCAS, hEDS, migraine, IBS, endometriosis, sleep apnea, depression, anxiety, MCI); the 85-90% cognitive dysfunction prevalence with information processing speed, working memory and sustained attention as dominant deficits; the central directionality risk that a synaptogenic peptide could plausibly consolidate rather than weaken pathologically over-driven sensorimotor and limbic post-exertional responses; the Polli BDNF directionality paradox; the HGF/c-Met synaptogenic mechanism of Dihexa (Benoist 2014 JPET; Wright & Harding 2015); the fosgonimeton (ATH-1017) Athira LIFT-AD Phase 3 failure and SHAPE PDD/DLB discontinuation as a cautionary clinical analogue; the UK NHS ME/CFS specialist clinic provision gap in Scotland, Wales (outside Betsi Cadwaladr UHB North Wales 2025) and Northern Ireland; Action for ME (0117 927 9551), ME Association ME Connect (0344 576 5326), Forward-ME, #ThereForME, 25% ME Group; and the complete absence of any human Dihexa trial data in any ME/CFS, post-viral fatigue or Long COVID population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in obstructive sleep apnea (OSA) brain fog, intermittent-hypoxia hippocampal damage, post-CPAP cognitive impairment, REM-sleep-specific CA1 hippocampal volume loss or any sleep-disordered breathing population. Covers ~13 million UK adults estimated to have OSA (~19.5% prevalence, 80-85% undiagnosed) on Sleep Apnoea Trust Association and Asthma + Lung UK denominators, the December 2024 FDA approval of Zepbound (tirzepatide) as the first ever prescription medicine for moderate-to-severe OSA with obesity on the back of SURMOUNT-OSA (NEJM, June 2024) showing 25-29 events/hour AHI reduction and 18-20% weight loss, the May 2025 University of California Irvine paper linking REM-sleep hypoxemia to CA1 hippocampal volume loss and memory impairment in older adults at risk for dementia (PMC11555004), the 2025 systematic review and meta-analysis across 23 studies and 33,226 patients estimating 36.92% pooled prevalence of cognitive impairment in OSA (PMC12537604), the 2025 PMC12022498 hippocampal-volume / T90 / SpO2 imaging study, the April 2025 Singh et al. Neurology paper on hypoxemia, white matter hyperintensities and temporal lobe changes, the Sunnybrook NCT06773416 CPAP cognition RCT (Feb 2025-Sep 2027), the CRESCENDO NCT06983769 CPAP vs MAD trial in cognitively impaired patients (Jan 2026-Dec 2030), the Brain Fog in Sleep Apnea trial (NCT06664450), NICE NG202 (August 2021) OSA/OHS in over-16s with the AHI 5-14.9 mild / 15-29.9 moderate / ≥30 severe grading, NICE IPG598 (2017) hypoglossal nerve stimulation with UCLH as a lead NHS Inspire centre, the Epworth Sleepiness Scale and STOP-BANG screening tools, home sleep apnoea testing and in-laboratory polysomnography, auto-CPAP and mandibular advancement devices (MAD), positional therapy, the OSA comorbidity cluster (resistant hypertension, atrial fibrillation, type 2 diabetes, stroke 3x risk, heart attack 4x risk, HFpEF, Long COVID, refractory migraine and morning headache, menopause, ADHD, depression, anxiety, erectile dysfunction), BDNF reduction under chronic intermittent hypoxia, beta-amyloid accumulation and glymphatic clearance, the HGF/c-Met synaptogenic and angiogenic mechanism of Dihexa (Benoist 2014 JPET; Wright & Harding 2015), fosgonimeton (ATH-1017) Athira LIFT-AD Phase 3 failure and SHAPE PDD/DLB discontinuation, modafinil / solriamfetol residual sleepiness context, the post-CPAP residual-cognitive-deficit population as the theoretical target group, the OSA-undiagnosed contribution to MCI, Long COVID brain fog and post-stroke cognitive impairment, and the complete absence of any human Dihexa trial data in any obstructive sleep apnea, central sleep apnea or chronic intermittent hypoxia population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in fibromyalgia (FM), fibromyalgia syndrome (FMS), fibro fog cognitive dysfunction, chronic widespread pain, nociplastic pain, central sensitisation syndromes, or the overlap conditions ME/CFS and Long COVID. Covers the ~2.8 million UK adult fibromyalgia population (~5.4% adult prevalence on Versus Arthritis / Fibromyalgia Action UK / Royal College of Physicians 2022 denominators); the 15 August 2025 FDA approval of Tonix Pharmaceuticals’ Tonmya (TNX-102 SL, sublingual cyclobenzaprine) as the first new FDA-approved fibromyalgia medication in 15 years (after pregabalin 2007, duloxetine 2008, milnacipran 2009), with Q4 2025 US commercial launch and the RELIEF and RESILIENT Phase 3 trials in nearly 1,000 patients hitting the 14-week pain endpoint and demonstrating reassuring safety; the ACR Convergence 2025 (November 2025) low-dose naltrexone (LDN) positive readouts and the May 2025 Annals of Medicine and Surgery systematic review and meta-analysis (PMC12055162) showing clinically meaningful pain and function gains with vivid dreams the principal reproducible adverse effect; the April 2025 ME Association funding of a 9-month University of British Columbia LDN trial in ME/CFS and Long COVID led by Dr Luis Nacul; the Dickson Chemist (Glasgow) UK LDN supply chain and the variable NHS Integrated Care Board access barrier; the 2024 Polli et al. PLOS One systematic review and meta-analysis identifying significantly elevated peripheral BDNF as a candidate fibromyalgia biomarker (the opposite direction from the BDNF deficit pattern in Alzheimer’s, depression and schizophrenia that underpins most BDNF-promoting nootropic claims) and the mechanistic implications for any synaptogenic peptide claim via NMDA potentiation, KCC2 downregulation and GABAergic disinhibition driving central sensitisation; the Albrecht et al. 2018/2019 multi-site [¹¹C]PBR28 PET Brain Behavior & Immunity study from the Loggia / Massachusetts General Hospital / Harvard Medical School group as the first in vivo human evidence of TSPO glial / microglial activation in thalamus, dorsolateral and medial prefrontal cortex, precuneus and anterior cingulate / insular cortex; the 2025 Exploration of Immunology and 2025 Cureus (PMC11853252) neuroinflammation reviews; the January 2026 Brain Sciences Montreal Cognitive Assessment case-control study consolidating >70% prevalence of measurable cognitive dysfunction and identifying pain severity, sleep quality, anxiety, depression and FIQR as independent predictors; the Royal College of Physicians 2022 first formal UK diagnostic guideline endorsing primary-care diagnosis using the ACR 2016 Widespread Pain Index + Symptom Severity Scale with 3-month chronicity; NICE NG193 (April 2021) chronic primary pain and the controversial recommendation against initiating paracetamol, NSAIDs, benzodiazepines, opioids and gabapentinoids (pregabalin, gabapentin) for chronic primary pain with only amitriptyline / citalopram / duloxetine / fluoxetine / paroxetine / sertraline permitted off-label; ICD-11 reframing as chronic primary musculoskeletal pain (MG30.01); the Moldofsky & Smythe 1975 alpha-EEG intrusion sleep architecture story and the bedtime-dosing rationale for Tonmya / amitriptyline / nortriptyline; the Oaklander 2013 Pain finding of intraepidermal nerve fibre density small fibre neuropathy in ~50% of fibromyalgia patients; central sensitisation / nociplastic pain framing (Clauw); the dense comorbidity cluster covering ME/CFS, Long COVID, IBS, migraine, TMD, restless legs syndrome, interstitial cystitis, endometriosis, hypermobile Ehlers-Danlos syndrome (hEDS), depression (60-80% lifetime), anxiety (50-70% lifetime), PTSD and adverse childhood experiences, mast cell activation syndrome; the off-label UK self-management ecosystem (CBD, medical cannabis, palmitoylethanolamide PEA, vitamin D, magnesium glycinate, CoQ10, melatonin, SAMe, 5-HTP, bacopa, ashwagandha, tDCS / rTMS); the HGF/c-Met synaptogenic mechanism of Dihexa (Benoist 2014 JPET PubMed 24403718; Wright & Harding 2015); the absence of any Russo HGF-deficiency series in fibromyalgia in contrast to the parallel papers in depression, anxiety, bipolar, autism and OCD; fosgonimeton (ATH-1017) and the absence of any pain-population testing in the Athira Pharma LIFT-AD / ACT-AD / SHAPE programmes; the central directionality risk that a synaptogenic BDNF-elevating HGF/c-Met-activating peptide could plausibly consolidate rather than weaken central sensitisation in a disorder where BDNF is already pathologically elevated (the fibromyalgia analogue of the central-gain risk in tinnitus, the CSTC-consolidation risk in OCD, the manic-switch risk in bipolar disorder and the prodromal-psychosis risk in schizophrenia); and the complete absence of any human Dihexa trial data in any fibromyalgia, chronic widespread pain or nociplastic pain population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in obsessive-compulsive disorder (OCD), body dysmorphic disorder (BDD), pure-O OCD, contamination OCD, harm OCD, relationship OCD (ROCD), scrupulosity, paediatric PANDAS / PANS, perinatal OCD, schizo-obsessive OCD, or any obsessive-compulsive spectrum condition. Covers the ~750,000 UK adult OCD population (1.2% point prevalence, 1-2% lifetime on Priory 2026 / OCD-UK figures), one of the WHO’s top-10 most disabling medical conditions worldwide; the 2013 Russo & Pietsch Biomarker Insights paper finding significantly decreased plasma hepatocyte growth factor (HGF), gamma-aminobutyric acid (GABA), urokinase plasminogen activator (uPA) and uPAR in OCD versus neurotypical controls (with low uPA / uPAR correlating with Y-BOCS symptom severity) — the single most direct biological link between Dihexa’s HGF/c-Met pharmacology and any psychiatric condition; the 2025 Gonzalez Journal of Neurochemistry review reframing OCD as an astrocyte disorder centred on Crym-positive striatal astrocytes gating perseverative behaviour through cortico-striatal presynaptic regulation; the 2025 Zhu Psychiatry & Clinical Neurosciences 1H-MRS meta-analysis consolidating decreased striatal NAA and elevated thalamic choline as the OCD neurometabolic signature; the 2025 Frontiers in Psychiatry static and dynamic striatal-subregion functional-connectivity paper mapping the ventromedial-vs-dorsolateral caudate abnormalities; the September 2025 Biohaven troriluzole (BHV-4157) Phase 3 PROUDD-1 / PROUDD-2 adjunctive-OCD-on-SSRI trial failures with no efficacy signal (NCT04693351 / NCT04641143 / NCT04708834); the Yale OCD Research Clinic (Pittenger group) randomised, double-blind, placebo-controlled, non-crossover single-dose psilocybin protocol and the parallel repeated-dosing study; Compass Pathways COMP360 25 mg synthetic psilocybin Phase 3 success in treatment-resistant depression (COMP005 2025 and COMP006 2026) with no Phase 3 OCD readout to date; the 2024 Mansueto Journal of Affective Disorders paper showing serum BDNF increases mediate cognitive recovery in OCD treatment responders; NICE CG31 (November 2005) with the confirmed autumn 2026 update consultation; the cortico-striato-thalamo-cortical (CSTC) circuit (orbitofrontal cortex, anterior cingulate, pre-SMA, ventromedial caudate, mediodorsal and ventral anterior thalamus); the BDNF Val66Met polymorphism; the SLC1A1 / GRIN2B / SLITRK5 / SAPAP3 genetic backbone; the GABAergic parvalbumin-interneuron deficit and its mechanistic alignment with HGF/c-Met biology; NHS Talking Therapies (formerly IAPT) ERP-based CBT pathway; high-dose SSRIs titrated to BNF maximum (fluoxetine, sertraline, fluvoxamine, paroxetine, escitalopram, citalopram), clomipramine, low-dose antipsychotic augmentation (risperidone, aripiprazole, quetiapine); the glutamate-modulator augmentation literature (N-acetylcysteine, memantine, riluzole, lamotrigine, topiramate, inositol, ondansetron, ketamine, CBD); FDA Humanitarian Device Exemption ventral-capsule / ventral-striatum DBS (Medtronic Reclaim, 2009) and the UK Cambridge bed nucleus of the stria terminalis (BNST) sham-controlled trial (2021); BrainsWay deep TMS H7 coil FDA approval (2018) and NICE IPG 709 (2021); bilateral anterior capsulotomy, anterior cingulotomy and MRgFUS focused ultrasound for the refractory tail; UK tertiary specialist services (South London & Maudsley Anxiety Disorders Residential Unit at Bethlem, Oxford Health OXTOP, Springfield Hospital London, Cambridge / Oxford / Bristol / Frenchay DBS centres); OCD-UK (Ashley Fulwood) and OCD Action and the International OCD Foundation (IOCDF); the OCD-depression comorbidity (60-65% lifetime), OCD-anxiety (30-50%), OCD-tic / Tourette / PANDAS-PANS overlap, OCD-bipolar (10-15%, manic-switch concern), OCD-schizophrenia (12-25% schizo-obsessive presentation, prodromal-psychosis concern); the OCD suicide-risk amplification (5-10× general population, 30% lifetime ideation, 10% lifetime attempt); the central directionality risk that augmenting BDNF/TrkB-dependent synaptic plasticity in a pathologically over-strengthened CSTC loop could plausibly consolidate rather than weaken the maladaptive learned compulsions; the ERP-augmentation reframe via extinction-learning consolidation (d-cycloserine analogue); the HGF/c-Met synaptogenic mechanism of Dihexa (Benoist 2014, JPET; Wright & Harding 2015); fosgonimeton (ATH-1017) and the absence of any anxiety / OCD spectrum testing in the Athira programme; and the complete absence of any human Dihexa trial data in any OCD or obsessive-compulsive spectrum population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in tinnitus, hyperacusis (loudness / annoyance / fear / pain subtypes), cochlear synaptopathy (‘hidden hearing loss’), somatic tinnitus, pulsatile tinnitus, sensorineural hearing loss, presbycusis, noise-induced hearing loss or any otologic indication. Covers the ~7.6 million UK adult tinnitus population on Tinnitus UK (British Tinnitus Association) and RNID figures with ~1.5 million severely affected, the February 2026 American Journal of Audiology peer-reviewed real-world evaluation of Lenire bimodal neuromodulation (Neuromod Devices, Dublin) reporting 81.8% clinically significant reduction in bothersome tinnitus after 12 weeks consolidating the March 2023 FDA De Novo authorisation backed by the TENT-A3 pivotal trial, the Susan Shore / University of Michigan / Auricle Inc signal-timing device 2023 JAMA Network Open randomised clinical trial in somatic tinnitus and the still-pending early-2026 FDA status, the July 2025 Frontiers in Neuroscience review by Lopes and colleagues consolidating BDNF as a central regulator of maladaptive auditory synaptic plasticity in tinnitus pathogenesis and treatment, the foundational Kujawa & Liberman 2009 Journal of Neuroscience cochlear synaptopathy paper showing noise exposure can destroy ~50% of inner-hair-cell ribbon synapses with no audiogram change in CBA/CaJ mice with permanent ABR wave I amplitude reduction, the 2025 Wang et al. Advanced Science noise-induced hidden hearing loss mechanism review, the 2022 Frontiers in Neuroscience meta-analysis of ABR-detected cochlear synaptopathy in tinnitus patients with normal hearing thresholds, NICE NG155 (March 2020) Tinnitus: assessment and management and its red-flag criteria (sudden sensorineural hearing loss within 72 hours, unilateral tinnitus, pulsatile tinnitus, focal neurology, severe distress with suicidal thinking), the British Society of Audiology high-frequency audiometry, the central-gain hypothesis of homeostatic plasticity in the dorsal cochlear nucleus, inferior colliculus and auditory cortex, the Jastreboff neurophysiological model of tinnitus distress, somatic tinnitus head-neck-jaw modulation, the Otonomy OTO-313 (intratympanic gacyclidine NMDA antagonist) Phase 2 failure in August 2022 and the Spiral Therapeutics OTIVIDEX / OTO-510 / OTO-413 (recombinant BDNF) asset acquisition, the Frequency Therapeutics FX-322 (Lgr5+ cochlear progenitor cells) hearing-loss-programme abandonment and Korro Bio merger, the Decibel Therapeutics / Regeneron DB-OTO AAV-based otoferlin gene therapy in OTOF-mutation paediatric hearing loss, the Audion BB103 (LY3056480, Notch inhibitor) Phase 1/2 progenitor-cell programme, the Hashir Tinnitus Clinic Annual Tinnitus Report 2026 covering 446 peer-reviewed studies, the NICE NG155-aligned NHS audiology pathway (CBT first-line for tinnitus distress, sound therapy, hearing aids, tinnitus retraining therapy), the UK private-pay Lenire route (~£2,500-3,500), NICE TA566 cochlear implants for severe-to-profound bilateral deafness, the HGF/c-Met synaptogenic mechanism (Benoist 2014, JPET) and the directionality concern that augmenting plasticity in an already-maladaptive auditory system could plausibly worsen rather than relieve the phantom percept, the fosgonimeton (ATH-1017) Alzheimer’s clinical analogue that has never been tested in any otologic indication, and the complete absence of any human Dihexa trial data in any tinnitus, hyperacusis, cochlear synaptopathy or hearing-loss population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in bipolar disorder, bipolar I, bipolar II, bipolar depression, mania, mixed affective episode, rapid cycling, schizoaffective disorder bipolar type or the residual bipolar cognitive impairment that persists into euthymia. Covers the ~1% UK adult prevalence (approximately 660,000 people) on Mental Health Foundation and NHS England Adult Psychiatric Morbidity Survey 2023-24 denominators, the 2025 NCISH National Confidential Inquiry report documenting 1,491 patient suicides with a primary bipolar diagnosis (8% of all patient suicides) and a 19% increase in 2019-2022 versus 2015-2018, the March 2025 UCL analysis of why bipolar suicide rates are so high, the Hayes et al. UK retrospective 5-year cohort of 2,649 people with bipolar disorder, the November 2025 FDA approval of Intra-Cellular Therapies / Johnson & Johnson Caplyta (lumateperone) as adjunctive major depressive disorder therapy on top of its existing US bipolar I and II depression indication as monotherapy and adjunct with lithium or valproate, the September 2025 UK MHRA reauthorisation of semi-sodium valproate for mania when lithium is not tolerated or contraindicated (subject to the Pregnancy Prevention Programme), the cariprazine (Vraylar/Reagila) paediatric Phase 4 programme enrolling ~380 patients aged 10-17 with bipolar I across ~60 sites worldwide and the cariprazine D3-imaging Phase 4 mechanistic study, lithium as gold-standard neuroprotective psychotropic (Hajek 2012 hippocampal-volume meta-analysis showing the bipolar deficit is masked by lithium exposure, Yucel 2007 longitudinal bilateral hippocampal volume increases on long-term lithium, Kakhki 2016 voxel-based morphometry in elderly bipolar patients with verbal memory gains over 4 years, the 2025 lithium-neuroprotection cytoskeletal-proteomic translational mechanism review consolidating the GSK-3β-inhibition / BDNF-upregulation / tau-dephosphorylation / amyloid-β42-reduction case), the often-overlooked Russo 2010 finding that serum hepatocyte growth factor (HGF) is decreased in bipolar disorder and normalises with zinc and antioxidant therapy as the single most direct biological link between Dihexa’s HGF/c-Met mechanism and bipolar pathology, the Grande 2010 BDNF-as-mediator-of-neuroplasticity case, the 2021 Cambridge BJPsych Open BDNF study in newly-diagnosed patients and unaffected first-degree relatives, ketamine and esketamine in bipolar depression (Salloum 2024 real-world cohort of 38 patients with 39% response and 13% remission and no manic switch; the 2025 retrospective cohort of 2,126 patients on esketamine showing significantly lower suicide outcomes at 1-7 days through 1 year; the 2024 IV ketamine bipolar systematic review and meta-analysis), AXS-05 (dextromethorphan-bupropion / Auvelity) BDNF/TrkB engagement, the KarXT Cobenfy bipolar I mania Phase 4 commitment, NICE CG185 standard of care, the theoretical manic-switch risk of any synaptogenic intervention, NHS shared-care lithium prescribing and monitoring, Bipolar UK, Mind, Rethink Mental Illness, the Samaritans crisis helpline 116 123 and the complete absence of any human Dihexa trial data in any bipolar disorder population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide like Dihexa has any role in chronic traumatic encephalopathy (CTE), traumatic encephalopathy syndrome (TES), or the long-term consequences of repetitive head impact (RHI) exposure. Covers the January 2026 Boston University CTE Center 614-brain-donor study in Alzheimer’s & Dementia establishing CTE as a distinct cause of dementia (~4× odds at high stage, comparable to advanced Alzheimer’s pathology); the May 2026 Boston University paper showing the proposed clinical TES criteria identify only 24% of autopsy-confirmed CTE cases with serious misdiagnosis concerns in athletes and veterans; the active UK group action by more than 1,100 former rugby union and rugby league players (including 2003 England World Cup-winning squad members Steve Thompson, Mark Regan and Phil Vickery, and Welsh internationals Gavin Henson, Colin Charvis and Ryan Jones) against World Rugby, the RFU, the WRU and the RFL, next scheduled for review in March 2026; the 2023 Glasgow / Sydney / Boston rugby brain-bank study (~68% CTE in 31 donors, with risk increasing with career length); the 2017 Boston University NFL paper (CTE in 99% of 111 examined NFL players); the four CTE pathology axes (perivascular hyperphosphorylated p-tau at sulcal depths, blood-brain barrier leakage, chronic microglial activation, synaptic loss), the McKee 2023 neuropathological staging I-IV, the sub-concussive head impact biology, dynamic contrast-enhanced MRI of BBB leakage as a 2026 early-warning imaging biomarker, plasma neurofilament light chain (NfL) and p-tau-181 / p-tau-217 / p-tau-231 blood biomarkers, the 2025 bioRxiv spatially resolved transcriptomics CTE signature, the UCSF Brain Injury Clinical Trials 2026 programme, the early-phase mood-behavioural CTE phenotype (depression, impulsivity, suicidality) versus the late-phase progressive cognitive phenotype, the FIELD Scottish footballer mortality study and FA under-12s heading limits, dementia pugilistica and boxing CTE, soccer heading, ice hockey, MMA, and military blast RHI cohorts, the World Rugby / Drake Foundation / University of South Wales elite player Brain Health Service, the Imperial College London Sport Concussion Service, the NHS Op COURAGE veterans pathway, NICE NG97 dementia diagnostic pathway, the 2024 Lancet Commission 14 modifiable dementia risk factors covering 45% of cases, the HGF/c-Met synaptogenic mechanism mapped onto each CTE pathology axis (very weak case for tau, plausible for BBB sealing, plausible for microglial repolarisation, plausible for synaptogenesis), the fosgonimeton (ATH-1017) LIFT-AD / ACT-AD / SHAPE clinical analogue, and the complete absence of any human Dihexa trial data in any CTE, TES, suspected-CTE, former contact-sport athlete, or military blast-exposure population.

Rigorous 2026 UK evidence review of whether GLP-1 receptor agonists (semaglutide / Ozempic / Wegovy / Rybelsus, tirzepatide / Mounjaro / Zepbound, liraglutide, exenatide, dulaglutide) protect or harm the brain, where a synaptogenic HGF/c-Met peptide like Dihexa converges on the same downstream BDNF / synaptic-plasticity axis, and where the NHS Mounjaro rollout actually stands in 2026. Covers the November 2025 Novo Nordisk EVOKE / EVOKE+ Phase 3 trials of oral semaglutide (Rybelsus) versus placebo in 3,808 adults with early symptomatic Alzheimer’s disease (no CDR-SB or secondary cognitive/functional benefit at 104 weeks despite ~10% reductions in neuroinflammation and AD-related biomarkers; 1-year extension discontinued), the AD/PD 2026 full readout, the 2025 JAMA Network Open cohort (n>60,000 with T2DM and obesity, HR 0.63 for incident dementia with semaglutide or tirzepatide vs other antidiabetics), the US Department of Veterans Affairs ~200,000 patient cohort (lower neurocognitive-disorder incidence), the 2024 target-trial emulation across 1,710,995 patients (40-70% lower 3-year AD-related dementia incidence on semaglutide vs insulin), the Daly et al. 2025 Alzheimer’s & Dementia case for APOE4-homozygote prevention trials, the GLP-1R / cAMP / PKA / CREB / BDNF mechanism plus AMPK, anti-neuroinflammatory microglial polarisation and the ‘type 3 diabetes’ brain-insulin-resistance hypothesis, the ‘Ozempic brain fog’ phenomenology and its mundane mechanisms (hypoglycaemia, dehydration, protein/B-vitamin/micronutrient gaps from rapid caloric restriction, metabolic transition), the NHS England weight-management-injection rollout milestones (23 March 2025 specialist services, 23 June 2025 primary-care expansion, 1 April 2026 QOF GP-contract integration under NICE TA1026, targeting 220,000 patients in three years), the BMI 40 / BMI 35 with comorbidity eligibility and the 2.5 kg/m² reduction for South Asian, Chinese, other Asian, Middle Eastern, Black African and African-Caribbean populations, NICE TA875 Wegovy in specialist weight management, the SELECT cardiovascular outcomes trial (20% MACE reduction in obesity without diabetes), FLOW (kidney outcomes in T2DM with CKD), STEP-HFpEF (heart failure with preserved ejection fraction in obesity), SURMOUNT-OSA (tirzepatide FDA approval for OSA in obesity December 2024), the exenatide-PD2 (Athauda 2017 Lancet) positive Parkinson’s signal and the Cleveland Clinic NLY01 Phase 2 negative read, the NIHR Oxford Health BRC 2025 study finding semaglutide safe for brain health with possible benefits for cognition and nicotine dependence, the EMA suicidal-ideation review and the semaglutide NAION optic-neuropathy signal, the retatrutide / orforglipron / CagriSema next-generation incretin pipeline, the convergence of the GLP-1R cAMP/PKA/BDNF axis with the HGF/c-Met MAPK/PI3K/BDNF axis downstream, and the complete absence of any human Dihexa trial data in any GLP-1 RA-treated population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide could help schizophrenia, schizoaffective disorder, first-episode psychosis, treatment-resistant schizophrenia, cognitive impairment associated with schizophrenia (CIAS), negative symptoms or prodromal CHR-P / UHR psychosis. Covers the ~220,000-strong UK schizophrenia patient base on the Royal College of Psychiatrists National Audit of Psychosis denominator, the April 2026 OHID / NHS England severe-mental-illness prevalence model (0.31-0.43% across English regions, highest in London), the September 2024 FDA approval of Bristol Myers Squibb’s KarXT / Cobenfy (xanomeline-trospium) as the first non-D2 schizophrenia mechanism in ~30 years and the 2026 UK MHRA submission and launch plan at ~$22,500 annual list price, the ARISE adjunctive Phase 3 negative read, the January 2025 Boehringer Ingelheim iclepertin (BI 425809) CONNEX Phase 3 failure across 1,840 patients in 41 countries with CONNEX-X discontinuation, the AbbVie / Cerevel emraclidine EMPOWER-1 and EMPOWER-2 Phase 2 failures, the ulotaront DIAMOND Phase 3 failure, the Sekar et al. Nature 2016 C4 complement synaptic-pruning hypothesis and the 2025 Frontiers in Synaptic Neuroscience extension, BDNF Val66Met negative-symptom association, the MET schizophrenia GWAS Caucasian signal and the CommonMind Consortium HGF mRNA upregulation, the HGF/c-Met GABAergic interneuron biology, NICE CG178, NG191 antipsychotic monitoring, clozapine for treatment resistance, the NHS England EIP two-week waiting-time standard, OASIS Maudsley CHR-P prodromal service, CIRCuiTS cognitive remediation, Rethink Mental Illness, Mind, the Hearing Voices Network and the complete absence of any human Dihexa trial data in any psychotic disorder.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide could help Huntington’s disease (HD), juvenile HD (JHD), late-onset HD, pre-manifest gene-positive carriers or any HD subpopulation. Covers the ~7,000 UK HD patients under Huntington’s Disease Association (HDA) care and the 1-in-10,000 community prevalence, the September 2025 uniQure AMT-130 AAV gene-therapy ~75% slowing of disease progression on cUHDRS at 36 months announced jointly with UCL/UCLH and the Cardiff Advanced Neurotherapies Centre (ANTC) as the only UK surgical site, the November 2025 break with the FDA, the 2 March 2026 FDA Type-A meeting requiring a prospective, randomised, double-blind, sham-surgery-controlled Phase 3 before any BLA, the Wave Life Sciences WVE-003 SELECT-HD Phase 1b/2a first clinical demonstration of allele-selective mutant huntingtin lowering (46% mean CSF mHTT reduction at 30 mg) with preservation of wild-type huntingtin and a caudate atrophy correlation, the PTC Therapeutics PTC518 / votoplam PIVOT-HD 24-month interim extension reporting 52% slowing of cUHDRS at 10 mg in Stage 2 HD versus a propensity-weighted natural-history cohort, the Novartis-led global INVEST-HD Phase 3 launch under the 2024 PTC-Novartis licensing deal, the Roche tominersen GENERATION HD1 failure and ongoing GENERATION HD2, the Novartis branaplam VIBRANT-HD termination, the SAGE-718 (dalzanemdor) SURVEYOR-HD failure, the CAG-trinucleotide-repeat HTT expansion biology, the somatic-instability axis (MSH3, FAN1, PMS1, LIG1), the BDNF deficiency in HD striatum and the corticostriatal BDNF/TrkB axis driving medium spiny neuron loss, the HGF/c-Met synaptogenic case, NHS NICE tetrabenazine and the deutetrabenazine / valbenazine VMAT2 family for chorea, the UCL Huntington’s Disease Centre, Cardiff University Huntington’s Disease Centre, the HDA Specialist Advisor service, Scottish Huntington’s Association, Brain Research UK, ENROLL-HD and HDClarity, CHDI Foundation, HDBuzz, the UK predictive genetic testing pathway, Mental Capacity Act 2005 considerations, juvenile and late-onset HD, and the complete absence of any human Dihexa trial in any HD population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide could help dementia with Lewy bodies (DLB), Parkinson’s disease dementia (PDD), mild cognitive impairment with Lewy bodies (MCI-LB), prodromal DLB or REM sleep behaviour disorder. Covers the ~100,000-strong UK DLB patient base (10-15% of all UK dementia, 3rd most common), the December 2025 CervoMed RewinD-LB extension-phase positive results for the oral p38α MAP kinase inhibitor neflamapimod, the April 2026 AAN Chicago first-ever placebo-controlled MRI evidence that neflamapimod increased basal forebrain volume and functional connectivity in DLB, the FDA alignment on a 300-patient registration-enabling Phase 3 starting H2 2026, the Norwegian ANeED Phase IIa ambroxol trial targeting GBA1 glucocerebrosidase biology, the AD/PD 2026 analysis showing strongest effects in DLB without AD co-pathology, the maturation of alpha-synuclein seed-amplification assays (aSyn-SAA / RT-QuIC) at ~87% CSF accuracy, the 2024 Movement Disorder Society biomarker-based research criteria for prodromal DLB and MCI-LB, the Lancet Neurology 2025 evolving DLB therapeutic landscape review, NICE NG97 recommendations on rivastigmine and donepezil, the severe neuroleptic / antipsychotic sensitivity profile, the Robin Williams / Susan Schneider Williams advocacy legacy, the LBDA 2026 Annual Meeting, Parkinson’s UK, the Newcastle Lewy Body Lab, GBA1/SNCA/APOE/LRRK2 genetic backbone, the basal-forebrain cholinergic biology that maps onto HGF/c-Met synaptogenic signalling, the DLB vs PDD one-year rule, the fosgonimeton SHAPE PDD signal, the prasinezumab PADOVA and minzasolmin ORCHESTRA adjacent programmes, and the complete absence of any human Dihexa trial data in any Lewy body population.

Rigorous 2026 UK evidence review of whether a synaptogenic, angiogenic, BBB-sealing HGF/c-Met peptide could help vascular dementia (VaD), vascular cognitive impairment (VCI), subcortical ischaemic vascular dementia, multi-infarct dementia, post-stroke dementia, mixed Alzheimer-vascular dementia, cerebral small vessel disease, CADASIL or related conditions. Covers the ~150,000 UK VaD patient base (17% of all UK dementia, 2nd most common), the April 2026 UCLA Health vascular-cell-brain-cell inflammation mechanism and brain-repair breakthrough with a repurposed psoriasis drug, the April 2026 UNSW Sydney CHeBA Mendelian-randomization study nominating APOE, TOMM40, ERAP and SAA1-4 as causal targets, the University of Manchester Kir2.1 / amlodipine cerebral microcirculation rescue, the 2026 World Stroke Organization Vascular Dementia Fact Sheet, the 2024 Lancet Commission's 14 modifiable risk factors covering 45% of dementia, NICE NG97 guidance, the MarkVCID consortium biomarker frame, CY6463 and NAC trials, the 2025 Science Advances CADASIL phosphodiesterase-5 rescue paper, mixed Alzheimer-vascular pathology and the HGF/c-Met angiogenesis / BBB-sealing / synaptogenic biology that fits VaD more cleanly than any other indication on this site — with the complete absence of any human Dihexa trial in any vascular cognitive population.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide could help frontotemporal dementia (FTD), behavioural variant FTD (bvFTD), primary progressive aphasia (PPA), FTD-GRN, FTD-MAPT, FTD-C9orf72 or the ALS-FTD spectrum. Covers the 31,000-strong UK FTD patient base with an 80% NHS diagnosis gap (~3,000 formally diagnosed), the 21 October 2025 Alector latozinemab (AL001) Phase 3 INFRONT-3 failure in FTD-GRN despite 2-fold sustained plasma progranulin elevation, the 49% Alector workforce reduction, the April 2026 Denali / Takeda termination of the DNL593 (PTV:PGRN) collaboration with Denali regaining full rights, the Vesper Bio VES001 oral sortilin modulator SORT-IN-2 readout expected H2 2026 in asymptomatic GRN carriers, the Passage Bio PBFT02 AAV-PGRN gene therapy upliFT-D programme, the Wave Life Sciences WVE-004 FOCUS-C9 discontinuation in C9orf72-ALS/FTD, FTLD-tau vs FTLD-TDP molecular pathology, MAPT / GRN / C9orf72 monogenic causes, microglial dysfunction and complement-mediated synaptic pruning, the AFTD Hope Rising 2026 Benefit ($2.1M; Emma & Bruce Willis honoured with the Susan Newhouse Award; launch of the Emma & Bruce Willis Fund for Dementia Research), Cambridge Centre for Frontotemporal Dementia, UCL Rare Dementia Support, Alzheimer's Research UK, Dementia UK Admiral Nurse Helpline, NICE NG97, the SSRI off-label evidence base for behavioural symptoms, the GENFI international research network, and the complete absence of any human Dihexa trial data in any FTD subtype.

Rigorous 2026 UK evidence review of whether a synaptogenic HGF/c-Met peptide could help post-traumatic stress disorder, complex PTSD (ICD-11 CPTSD), acute stress disorder, treatment-resistant PTSD or moral injury. Covers the amygdala-vmPFC fear-extinction model, the 2010 Peters et al. Science paper showing infralimbic BDNF infusion is sufficient for fear extinction in extinction-failure animals, the BDNF / H3K9me2 epigenetic literature, the angiotensin IV / HGF/c-Met convergence onto BDNF downstream plasticity machinery, NICE NG116 first-line trauma-focused CBT and EMDR pathway, the MAPS / Lykos MHRA Innovation Passport for MDMA-assisted therapy, the August 2024 FDA Complete Response Letter on Lykos MDMA, ketamine and esketamine in PTSD, the 2025 stellate ganglion block systematic review and meta-analysis, NHS Op COURAGE for veterans and the 2024 Murthy et al. evaluation, KCMHR longitudinal data (7.4% overall, 17% combat-deployed), the 2025 CPTSD prevalence meta-analysis, Combat Stress, Forces in Mind Trust, and the complete absence of any human Dihexa trial data in PTSD.