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Not long ago, confirming Alzheimer’s disease during life took expensive PET imaging or a lumbar puncture. In recent years the picture has changed quickly: blood tests for specific proteins have appeared, along with drugs that slow the disease at an early stage. This is a technological shift that is important to understand and not to overrate.
What changed in diagnosis
The key new marker is phosphorylated tau, p-tau217, in plasma. In studies it correlates well with amyloid plaques in the brain on PET. In 2025 the FDA for the first time cleared for clinical use a plasma test based on the p-tau217 to amyloid-beta 42 ratio (Lumipulse) to help diagnose adults with symptoms. Note the wording: it is about confirming a diagnosis in a person with complaints, not mass screening of healthy people.
Reasons for caution: a positive result does not guarantee symptoms will appear or when; in some people the marker rises with kidney disease; and information about future risk without a means of intervention can do psychological harm.
What changed in treatment
Lecanemab (Leqembi) and donanemab (Kisunla), antibodies against amyloid, have been approved in the US and slowed cognitive decline in trials in people with early-stage disease. The effect is moderate, and treatment requires regular infusions and MRI monitoring because of the risk of brain swelling and microbleeds (ARIA). It is not a cure for dementia, but it is the first time drugs act on the biology of the disease. Availability and cost differ between countries.
What can be done now
The Lancet Commission on dementia, in its 2024 update, identified 14 modifiable risk factors and estimated that about 45% of dementia cases could in principle be prevented or delayed. The list: hypertension, hearing loss, high LDL cholesterol, smoking, diabetes, physical inactivity, obesity, excessive alcohol use, head injury, air pollution, social isolation, vision loss, depression and less education.
The 45% estimate is modelled, not a promise: it is the share that could be removed if the factors disappeared across the whole population. But the practical implications are clear: control blood pressure, check hearing and vision, stay active, do not smoke, keep up social contact. Hearing aids and hypertension treatment are among the best-supported measures.
What about “brain training” and supplements
Cognitive training apps improve performance on the trained tasks, but transfer to everyday memory and protection against dementia is weakly supported. Large supplements such as omega-3 and vitamins have not shown convincing prevention in people without deficiency. Multi-component lifestyle programs, such as the Finnish FINGER trial, gave a moderate benefit on cognitive tests but required a lot of effort and support.
What to do with this knowledge
- Do not buy commercial “Alzheimer’s risk panels” without a doctor’s order.
- If you notice persistent memory problems, early consultation gives more options than waiting.
- For everyone else, “brain health” means blood pressure, sleep, hearing, physical activity and social life.
For how technology fits into the broader picture of healthy aging, see our piece on healthspan .
