Condition

Alzheimer's Disease

Alzheimer's disease is a progressive neurodegenerative disorder marked by widespread loss of gray matter and decline in memory and cognition.

Nervous System

Justin Cooke, BHSc Clinical Herbalist · July 26, 2026 3 Differentials

Alzheimer’s disease is a progressive neurodegenerative disorder that steadily erodes the brain’s ability to store and retrieve memories. It involves a widespread loss of gray matter and visible shrinkage of the brain, with most of the early damage concentrated in the hippocampus, limbic system and frontal cortex. The condition typically progresses over 15–25 years toward complete immobility and dependence on care, and it is ultimately fatal. It is the most common cause of dementia, and while there is still no cure, the last few years have brought both the first drugs that modestly slow the disease and a much clearer picture of what actually goes wrong in the brain.

Stages of Alzheimer’s

Alzheimer’s is usefully seen as a slow progression through three broad stages, tracking the spread of damage across the brain.

Early stage. It begins with mild disorientation and difficulty with new memories — where the car keys are, what happened yesterday, the names of people just met. This reflects early damage in the hippocampus, the region that lays down long-term memory. Other early signs include difficulty finding the right words, trouble recalling recently read material, difficulty putting names to faces, and problems with planning.

Middle stage. As damage spreads outward toward the cerebral cortex, symptoms intensify and reach further back in time — even childhood memories begin to fade as neurons are lost. This stage brings forgetting of personal history, moodiness or antisocial reactions to challenge, confusion about time and place, disrupted sleep, becoming lost easily, and shifts in personality or behavior.

Late stage. After extensive neuronal loss the brain shows visible shrinkage, and the person needs assistance with nearly all daily activities — getting out of bed, bathing, using the bathroom. Communication becomes very limited, familiar faces are no longer recognized, and confusion and frustration are constant. Patients in end-stage disease can no longer ambulate, dress, bathe or care for themselves, and in many cases lose the ability to speak intelligible words at all. They become vulnerable to infection, which is a frequent cause of death.

What Causes Alzheimer’s

There is no single cause. The medical community has long debated it, and the picture that has emerged is not one pathological process but a series of pathogenic changes in nervous-system function, spanning both the peripheral autonomic network and the limbic system. Some frame the disease as a metabolic disorder — the so-called “type 3 diabetes” idea, in which brain cells become resistant to insulin — while others emphasize inherited genetic risk. Most researchers now see it as a mix of both, plus age and lifestyle.

Damage first shows up in the hippocampus, the region central to memory storage and to imagining future events. Over time it can be seen spreading throughout the brain, and on a large scale the loss of tissue becomes visible to the naked eye as the brain shrinks — mainly from the cerebral cortex, where the bulk of the gray matter sits.

At the microscopic level, several interlocking mechanisms drive the damage:

Misfolding & Aggregation of Proteins

The accumulation of abnormally folded proteins is the hallmark of the disease, and it comes in two forms. Tau normally stabilizes the tiny internal “tracks” that move cargo around a neuron; in Alzheimer’s it clumps into neurofibrillary tangles that choke the cell from the inside. Amyloid-beta is a sticky fragment produced when a larger protein in the neuron’s membrane — amyloid precursor protein (APP) — is cut up by enzymes called secretases. Normally these fragments are cleared away; in Alzheimer’s they clump into plaques between the neurons instead. Over time, both the tangles inside cells and the plaques outside them are associated with neuronal death.

The Acetylcholine Point of Confusion

Amyloid-beta does not come from the breakdown of acetylcholine. It comes from APP. Many traditional memory remedies — and the older Alzheimer’s drugs — act on acetylcholine instead, by slowing the enzyme acetylcholinesterase that breaks it down. Raising acetylcholine this way can ease symptoms by supporting memory and communication between neurons, but it does not slow the underlying disease or reduce how much amyloid the brain produces. Most of the herbs studied for Alzheimer’s work this way: they act on symptoms, not on the disease.

Metabolic & Mitochondrial Dysfunction

Impaired energy production within neurons — failing mitochondria and disrupted glucose metabolism — leaves brain cells unable to meet their energy demands. This energy deficit is thought to accelerate neuronal injury and death, and is the basis of the “type 3 diabetes” framing.

Calcium-Handling Impairment

Neurons normally regulate calcium tightly. In Alzheimer’s this control is lost, and the resulting sustained rise in intracellular calcium disrupts cell signaling and promotes degeneration.

Glial Cell Dysfunction & Neuroinflammation

Glial cells (astrocytes and microglia) normally support and protect neurons and clear away toxic debris. When their function is disturbed they instead contribute to a damaging, inflammatory environment. Chronic activation of the brain’s immune cells produces ongoing low-grade inflammation that — while initially protective — damages surrounding neurons and is increasingly recognized as a driver of disease progression. One measurable signal of this is the enzyme monoamine oxidase B (MAO-B), which is markedly elevated in the reactive astrocytes that swell up around amyloid plaques; the amount tends to track the local damage, which has made MAO-B a target for PET brain imaging.

Oxidative Damage

An excess of reactive oxygen species overwhelms the brain’s antioxidant defenses, damaging lipids, proteins and DNA. Neurons are especially vulnerable because of their high metabolic activity. MAO-B contributes here too: as it breaks down monoamine neurotransmitters like dopamine, it generates hydrogen peroxide and other reactive by-products that stress neurons.

Excitotoxicity

Excessive stimulation of neurons by the excitatory neurotransmitter glutamate — often through over-activation of NMDA receptors — lets harmful amounts of calcium into the cell. This over-excitation injures and ultimately kills affected neurons, and is the mechanism targeted by the drug memantine.

The Role of Stress

Stress is a well-recognized aggravating factor. The hippocampus, where the disease begins, is dense with glucocorticoid receptors that respond to stress hormones such as cortisol. In the short term this response is adaptive; in the long term, as in chronic stress, it does real damage. While it is not clear that stress alone can cause Alzheimer’s, it does nothing to prevent it and is likely to exponentiate the damage in the hippocampus. Adequate exercise, sleep, hydration, meditation, social connection, and avoiding added sugar are all reasonable stress-reduction measures.

Causative & Risk Factors

A number of factors are associated with Alzheimer’s and with dementia more generally:

Old age (>65)
Cardiovascular disease
Stroke
Hypertension
Hypercholesterolemia
Low folate intake
Down’s Syndrome
Diabetes
ApoE variations
Obesity
Depression
High caloric intake
Poor exercise
Social isolation
Heavy metal exposure
Medications (such as benzodiazepines)
Aspartame intake

Conventional Treatment & Drug Development

There is no cure, and the available drugs fall into two groups.

Symptomatic drugs raise or steady neurotransmitter levels without touching the underlying disease. The cholinesterase inhibitors — donepezil, galantamine and rivastigmine — slow the breakdown of acetylcholine and can ease memory and communication for a time. Memantine, an NMDA-receptor antagonist, dampens glutamate excitotoxicity and is used in moderate-to-severe disease. Both help symptoms; neither slows progression.

Disease-modifying drugs aim at the plaques directly. The anti-amyloid antibodies are the newest class: the first, aducanumab (Aduhelm), was approved in 2021 amid heavy controversy and then withdrawn from the market in 2024. Two successors — lecanemab (Leqembi, 2023) and donanemab (Kisunla, 2024) — are now FDA-approved and do modestly slow decline in early Alzheimer’s, though they carry real risks (brain swelling and small bleeds, collectively called ARIA) and are not cures. MAO-B inhibition has also been explored as a neurodegeneration angle — the prescription MAO-B inhibitor selegiline has been trialled in Alzheimer’s — but the evidence for lasting benefit has been underwhelming, so it remains a research direction rather than an established treatment.

Detecting Alzheimer’s Early

Much current research aims to identify Alzheimer’s before it becomes irreversible. Researchers have confirmed that amyloid and tau both play a significant role and interact with one another, and markers such as tau, amyloid-beta and MAO-B are all being explored as early signals — the goal being to measure them without dissecting the brain under a microscope. If reliable blood tests, cerebrospinal-fluid tests or imaging techniques can detect these changes early, the disease could be caught and treated long before symptoms appear.

A healthy brain compared with an Alzheimer's brain

The size difference is due to a massive loss of neurons, mainly from the cerebrum.

Presentation

Symptoms

The earliest and most prominent symptom is progressive memory loss, particularly of recently formed memories. As the disease advances it impairs language, reasoning, judgment and spatial orientation, and patients increasingly struggle with familiar tasks. Mood and personality changes, confusion and disorientation are common, and in the later stages affected individuals lose the ability to care for themselves.

Assessment

Diagnostic Considerations

Diagnosis rests on an acquired impairment in memory, associated with impairment in one or more cognitive domains:

Executive function (e.g., abstract thinking, reasoning, judgment)
Language (expressive or receptive)
Praxis (learned motor sequences)
Gnosis (ability to recognize objects, faces or other sensory information)

Impairments must be severe enough to interfere with work, usual social activities or relationships. Several standardized tests support the diagnosis, including the Mini Mental Status Exam (MMSE).

Other Tests Include:

Scans: CT or MRI to assess neuronal loss
Blood tests
- Full blood count
- ESR
- Urea
- Electrolytes
- Blood glucose
- Calcium
Liver function tests
Thyroid function tests
Vitamin B12
Syphilis culture
ANA
HIV serology
EEG

Assessment

Differential Diagnosis

Stroke
Cardiovascular disease
Diabetic dementia

Context

Comorbidities

Type II Diabetes
Stroke
Cardiovascular disease
Depression

Materia Medica

No herb has been shown to prevent or reverse Alzheimer’s disease.

Evidence: Strong — human RCT / meta-analysis Moderate — small or mixed human Preclinical — animal / in-vitro / mechanism Traditional only — no trial No benefit — studied, negative result

Chinese ClubmossHuperzia serrataStrong

Isolated huperzine-A is a reversible, BBB-penetrant acetylcholinesterase inhibitor working on the same cholinergic principle as donepezil; a 2013 meta-analysis of 20 RCTs (1,823 participants) found significant cognition and daily-living gains versus placebo ^{11Reference 11Yang G et al. · 2013Meta-analysisHuperzine A for Alzheimer’s disease: a systematic review and meta-analysis of randomised clinical trials — meta-analysisView study →}, and it is a licensed anti-Alzheimer’s drug in China.

The positive trials cluster in China with high bias risk, and the best-designed trial — a US ADCS Phase II RCT (n=210) — was negative on its primary cognitive endpoint at 200 µg twice daily ^{12Reference 12Rafii MS et al. · 2011RCTA phase II trial of huperzine A in mild to moderate Alzheimer disease — randomised controlled trialView study →}. All the evidence is for the microgram-dose isolated alkaloid, not the crude herb.