Alzheimer's disease: an animated, cited guide

This page needs JavaScript for its animations. The outline and key answers are below, and every claim in the full version carries a numbered citation.

Not medical advice. Alzheimer's Companion is an educational synthesis of published literature. It does not replace a clinician.

What is in it

What Alzheimer's is Dementia versus Alzheimer's, who it affects, the numbers.
The brain that forgets Where it starts and how it spreads, stage by stage.
Amyloid, animated From one protein cut to a plaque, and the debate about it.
Tau and the tangle How a scaffold protein turns into a tangle and spreads.
Microglia and the lost synapse Inflammation, pruning, and the strongest link to memory loss.
Genes and inheritance APOE, the dominant families, Down syndrome, and what a test means.
Twenty years before symptoms The biomarker cascade, in order.
Stages and symptoms From no symptoms to severe dementia, function by function.
Diagnosis and biomarkers Criteria, scans, spinal fluid, blood tests and screening tools.
The differential Delirium, vascular, Lewy body, frontotemporal and reversible causes.
Cholinesterase inhibitors and memantine Inside the synapse, and what the benefit really is.
Anti-amyloid antibodies over time Lecanemab and donanemab over 18 months, ARIA and the debate.
Beyond memory Agitation, mood, psychosis and sleep, and the drug cautions.
Lowering the risk The 14 modifiable risk factors and what trials show.
Living with dementia and caregiving Planning, safety, caregivers and the end of life.
Nursing care Assessment, giving the medicines, communication, documentation.
Toward a cure The pipeline, prevention trials, and the evidence for each route.
History and people From Auguste Deter in 1901 to the antibodies.
Flashcards and mnemonics Flip cards by topic.
Quiz Questions with explanations.
Glossary Every term, searchable.
Sources Every reference behind the app.

Part 4 · Living, caring, preventing

Lowering the risk

The 2024 Lancet Commission estimated how much dementia worldwide is linked to 14 risk factors that could, in principle, be changed. Play the wheel to build up its estimate, then pick any factor to see the evidence behind it and the caveats.

Timeline

Population attributable fractions from the Commission's Figure 9, rounded to whole numbers. Click a segment or a row, or use the buttons below.

What the prevention trials found

A risk factor linked to dementia in observational studies is not proof that changing it prevents dementia. Randomised trials test that. Play the plot to bring in each trial's main result; many are null or small.

Timeline

Dots are estimates; lines are 95% confidence intervals. A line that crosses the dashed no-effect line means the result is compatible with no effect. Units differ between rows, so compare each with its own zero.

Open questions

WHO 2019 and the Lancet Commission 2024

The two bodies weigh evidence differently. WHO grades recommendations on intervention evidence; the Commission models how much dementia each factor may account for.

Factor	WHO 2019 recommendation (evidence quality)	Lancet Commission 2024
Physical activity	Strong for normal cognition (moderate); conditional for MCI (low) ⁷⁷	Inactivity: about 2% ³²¹
Smoking	Stop smoking: strong (low) ⁷⁷	About 2% ³²¹
Diet	Mediterranean-like diet: conditional (moderate). Vitamin B, E, PUFA and multi-complex supplements: strong recommendation against (moderate) ⁷⁷	Not one of the 14 factors ³²¹
Alcohol	Reduce hazardous drinking: conditional (moderate, observational) ⁷⁷	Excessive alcohol: about 1% ³²¹
Blood pressure, diabetes	Manage per WHO guidelines: strong. To reduce dementia specifically: conditional (very low) ⁷⁷	Hypertension about 2%, diabetes about 2% ³²¹
Cholesterol	Manage dyslipidaemia in midlife: conditional (low) ⁷⁷	High LDL: about 7%, new in 2024 ³²¹
Hearing loss	No recommendation: intervention evidence insufficient ⁷⁷	About 7%, joint largest ³²¹
Depression, social isolation	No recommendation: insufficient evidence ⁷⁷	Depression about 3%, isolation about 5% ³²¹
Cognitive training	Conditional (very low to low) ⁷⁷	Not one of the 14 factors ³²¹