Alzheimer's disease

Alzheimer's disease is progressive dementia with amyloid plaques, neurofibrillary tangles, and gliosis. Mainstream research centers on genetics (APOE), amyloid clearance, and acetylcholine drugs.

In The problem of Alzheimer's disease as a clue to immortality, Ray Peat treated dementia as failed brain energy and protective inhibition: the aging brain faces the same oxygen, PUFA, estrogen, and glucose deficits that injure the fetal brain, not a separate "entropyz-only" fate.

The toxicity of estrogen and of the unsaturated fats has been known for most of the twentieth century, and much has been learned about their interactions in the aging process.

— Ray Peat

Fetal brain injury and aged brain parallels

At six months gestation the human fetal brain has about twice as many cells as at birth; in old age glial cells multiply while neurons die and brain DNA mass can exceed young-adult levels in Peat's cited measurements. Factors shrinking the brain at birth also injure the degenerating aged brain in his list: hypoxia, excess PUFA, estrogen excess, progesterone deficiency, and glucose lack.

Excessive supply of unsaturated fats in our diet, acting as a false-signal system, overcomes cholesterol, pregnenolone, and progesterone which are our main long-range defenses, and the resulting cascade of ineffective and defective reactions leads to lower and lower energy production, reduced function, and death.

— Ray Peat

Many people experience regenerative improvement when circumstances align, such as mountain air in spring with adequate social support optimizing basic regulatory systems.

Inhibiting prostaglandin E2 receptor EP2 on myeloid cells restores glucose oxidation, reduces neuroinflammation, and reverses age-related cognitive decline in mice, a pathway upstream of COX-derived PGE2 that aspirin also suppresses.

Gut LPS, miRNA-30b, and neurofilament loss

Microbiome-derived LPS upregulates miRNA-30b-5p in stressed neuronal-glial cells, suppressing neurofilament light chain and promoting cytoskeletal atrophy and synaptic disorganization seen in Alzheimer's pathology.

PUFA, estrogen, and iron

Excess dietary unsaturated fats act as false environmental signals, overwhelming cholesterol, pregnenolone, and progesterone defenses and lowering energy production.

The most highly unsaturated fats, including DHA, accumulate with aging, and their toxic fragments are increased in Alzheimer's disease.

— Ray Peat

Iron reacts with reductants and unsaturated oils to form lipid peroxides; absorption rises with estrogen and Hypothyroidism in Peat's regulatory summary. Endotoxin synergizes with unsaturated fats; naloxone opposes some toxic effects in citations on the same page.

Plaques as a protective response

Brain fatty-acid profiling linked Alzheimer's pathology to elevated docosahexaenoic, linoleic, arachidonic, linolenic, eicosapentaenoic, and oleic acids (all unsaturated), with no saturated fatty acids associated, supporting a metabolic-lipid basis for AD. A 2006 report that oligomeric amyloid-β*56 impairs memory in mice became one of the most-cited pillars of the amyloid hypothesis and redirected billions in drug development toward amyloid targets. Decades of drugs targeting beta-amyloid and tau plaques directly have almost uniformly failed to help patients, which is consistent with the plaques being a protective response rather than the primary cause of the disease. Tau protein has an independent, physiological role in glial cells: it is required for glia to form lipid droplets that sequester peroxidized lipids exported from stressed neurons, and glia lacking tau cannot protect neurons from this oxidative damage, a mechanism confirmed across fruit flies, rat astrocytes, and human glial cells. This fits the PUFA/endotoxin model above: plaque formation may be the brain's attempt to contain lipid peroxidation and oxidative damage from excess unsaturated fat and endotoxin exposure, rather than a random pathological byproduct.

Protective inhibition and hormones

Peat described ordinary sleep as restorative protective inhibition; weakened glycogen and energy charge with aging parallels hypothyroid night stress. Case histories in part 2 include progesterone restoring function in labeled epileptic dementia and thyroid with pregnenolone and progesterone clearing senile confusion within days.

One study has found that the only hormone abnormality in a group of Alzheimers patients' brains was an excess of DHEA... These observations suggest that DHEA should be used with caution. Supplements of pregnenolone and thyroid seem to be the safest way to optimize DHEA production.

— Ray Peat

Before structural plaque burden is advanced, Peat emphasized normalizing temperature, Magnesium, CO₂, sleep, and red light, then cautious thyroid and Progesterone rather than excess DHEA. Cytochrome oxidase defects appear in Alzheimer's tissue in work Peat cited. See Harm reduction.

Allopregnanolone (a progesterone/pregnenolone-pathway neurosteroid) is in active clinical development as a regenerative therapeutic for early Alzheimer's, with phase 1b/2a trials showing it promotes neurogenesis and restores hippocampal volume and cognitive markers rather than merely slowing decline.

LSD microdosing trials

Intermittent low-dose LSD (5–20 µg every four days for 21 days) was safe and tolerable in a phase 1 trial positioned toward Alzheimer's disease, with proposed anti-inflammatory mechanisms via 5-HT2A signaling.

PET imaging linked greater serotonin transporter loss and amyloid-beta deposition together to late-life depression risk, supporting a shared serotonin/amyloid pathway between depression and Alzheimer's rather than treating them as unrelated conditions that happen to co-occur.

Dopamine and neprilysin

Activating ventral tegmental dopamine neurons or L-DOPA treatment raises neprilysin and reduces β-amyloid plaques in Alzheimer's mouse models, with chronic L-DOPA improving memory performance.

High estradiol-to-progesterone ratios during perimenopause downregulate mitochondrial OXPHOS genes and reduce brain ATP; progesterone supplementation normalizes the ratio and restores synaptic function in Alzheimer-model mice.

Vitamin K2 vitamer MK7R hypermethylates and downregulates PSEN1, BACE1, IL-1β, and IL-6 while raising protective ADAM10/ADAM17 expression in neuroblastoma models of amyloidogenesis and neuroinflammation.

Autophagy-deficient human neurons die from NAD+ depletion driven by hyperactive SIRT and PARP enzymes; NAD precursor supplementation rescues mitochondrial energetics and survival.

Vitamin K and neuronal differentiation

Retinoic-acid-conjugated vitamin K analogues (Novel VK) cross the blood-brain barrier, convert to MK-4 more efficiently than natural K, and induce neural progenitor differentiation with stronger potency than menaquinone alone in Alzheimer's rodent models.

Cervical lymphatic shunting

A surgical cervical shunting procedure to unclog cerebral lymphatic drainage pathways (CSULS) produced measurable improvement in six Alzheimer's patients as of 2024, with transient delirium the only complication, resolving within 72 hours, and gains in attention and reaction speed across all six. In the reported first case (a 70-year-old woman treated at Shanghai Jiao Tong University's Alzheimer's disease center), five weeks post-surgery showed reduced tau-PET signal and improved glucose metabolism on FDG-PET, most evident in the right frontal lobe with additional gains in the left temporal lobe, alongside improved Mini-Mental Status Examination score (5→7), Clinical Dementia Rating, and depression scores.

Intermittent CO2 and glymphatic clearance

In a small human study (n=12), masks delivering intermittent ~5% CO2 alternating with normal air every 35 seconds for 30 minutes appeared to boost the brain's glymphatic clearance of tau and amyloid-beta, evidenced by elevated plasma amyloid-beta after sessions.

Mitochondrial metabolism and acetyl-CoA

In transgenic C. elegans expressing pan-neuronal human amyloid beta, metabolic stress (not amyloid aggregation per se) was the primary pathogenic event driving dysfunction, supporting metabolic failure as causally upstream of amyloid pathology rather than merely a downstream consequence of it.

Pharmacologic NAD+ restoration (P7C3-A20 NAMPT activator) reversed advanced amyloid and tau pathology and restored cognition in multiple Alzheimer's mouse models. In aged SAMP8 mice, experimental compounds that maintain brain acetyl-CoA levels (partly by inhibiting acetyl-CoA carboxylase 1) preserved mitochondrial gene expression, increased histone acetylation at memory-relevant sites, and improved cognitive performance, linking aging and dementia to shared defects in brain mitochondrial metabolism rather than irreversible plaque pathology alone.

Gut barrier, vitamin A, and amyloid

Vitamin A status in APP/PS1 mice modulates gut microbiota, intestinal permeability, and circulating inflammatory cytokines, with deficiency associated with higher brain amyloid-β deposition.

Nitrate exposure

Systemic LPS can produce amyloid plaques and cognitive deficits in mice without infectious prion protein, suggesting inflammatory endotoxin load as an upstream driver of protein-misfolding pathology. Drinking-water nitrate below current EU limits (as low as 5 mg/L) associates with higher dementia incidence in a large Danish cohort.

Glucocorticoid challenge enhances Aβ synthesis via 5-lipoxygenase; inhibiting or genetically removing 5-LO prevents dexamethasone-induced amyloid elevation in vitro and in mice.

Blocking constitutively active 5-HT7 receptors with the inverse agonist amisulpride prevented pathological tau buildup and cognitive deficits in preclinical Alzheimer models.

Repeated low-grade LPS exposures in middle-aged mice produced lasting deficits in inhibitory avoidance and Morris water-maze performance with disrupted hippocampal LTP, modeling infection-burden effects on cognitive aging.

A large observational cohort linked vitamin D supplementation before cognitive decline to substantially lower subsequent dementia incidence and longer dementia-free survival.

Decade-long low-dose aspirin use in coronary patients correlated with roughly one-third lower Alzheimer disease incidence and two-thirds lower vascular dementia in observational analysis.

Mendelian-randomization and observational analyses supported a causal protective effect of higher vitamin D on dementia and stroke risk, with up to 17% of dementia potentially preventable by correcting deficiency.

Transcranial photobiomodulation at 1068 nm raised ATP-related cognitive measures in healthy adults; separate pilot trials reported symptomatic gains in mild dementia.

People with mild cognitive impairment had lower carbohydrate oxidation and higher fat oxidation at rest than healthy elders, consistent with a hypometabolic prodromal Alzheimer phenotype.

A one-year benfotiamine trial produced significantly less ADAS-cog decline than placebo in patients with mild Alzheimer disease.

Endotoxin hypothesis

Elevated blood and CSF LPS in Alzheimer's patients may promote amyloid expression, tau phosphorylation, and microglial neurotoxicity via gut, lung, or periodontal bacterial sources.

Methylene blue (hydromethylthionine)

Pharmacokinetic reanalysis of phase III trials found concentration-dependent cognitive and anti-atrophy effects at 8 mg/day hydromethylthionine monotherapy, with predicted maximal benefit near 16 mg/day and reduced efficacy when combined with symptomatic AD drugs.

See also

• PUFA
• Estrogen
• Progesterone
• Iron
• Thyroid
• Gelatin