Memory Digest

Prevention Trials

Prevention trials test whether a drug or lifestyle program can delay or stop Alzheimer's before symptoms start; here is what major trials have found so far and how people without symptoms can take part.

Last reviewed: October 2026

Most Alzheimer's trials test treatments in people who already have symptoms. But the brain changes of Alzheimer's begin 15 to 20 years or more before memory problems appear. Prevention trials try to step in during that silent period, or even earlier, to delay or stop the disease before it does lasting damage.

Two kinds of prevention

• Primary prevention aims to stop disease from starting at all, usually by changing risk factors in the general population, such as blood pressure, physical activity or diet.
• Secondary prevention targets people who already have early brain changes, such as amyloid plaques seen on a PET scan or in a blood test, but no symptoms yet (sometimes called preclinical Alzheimer's; see Biomarkers).

Drug prevention trials: what we've learned

The A4 Study (solanezumab). This large trial enrolled 1,169 people aged 65 to 85 who had normal thinking but amyloid on their brain scans. They received the antibody solanezumab or a placebo for about four and a half years (240 weeks). Published in 2023, the results were disappointing: solanezumab did not slow cognitive decline compared with placebo. Researchers think the drug was too weak at clearing plaques, since it targets single amyloid molecules rather than the clumps that make up plaques. The study still taught the field a great deal, including that people with more amyloid at the start declined faster.

Newer anti-amyloid drugs. Lecanemab and donanemab, which do clear plaques, slowed decline modestly in people with early symptoms (see Lecanemab (Leqembi) and Donanemab (Kisunla)). Both are now being tested in people who have amyloid but no symptoms, in trials such as AHEAD 3-45 (lecanemab) and TRAILBLAZER-ALZ 3 (donanemab). Results were not yet available as of this writing. The key question is whether removing amyloid earlier works better than removing it after symptoms begin.

Families with inherited Alzheimer's. A small number of families carry rare gene changes that cause Alzheimer's in midlife almost every time (see Genetic Testing and APOE4 and Young-Onset Dementia). Because researchers know roughly when symptoms will start, these families have joined prevention trials, including the Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU) and a study in a large extended family in Colombia. So far, no drug has clearly prevented symptoms in these groups, but the trials continue with newer drugs.

Lifestyle and health prevention trials

Blood pressure: SPRINT MIND. In this trial of more than 9,000 adults with high blood pressure, aiming for a top number below 120 rather than below 140 reduced the combined risk of mild cognitive impairment or dementia. Dementia alone was not significantly reduced, partly because the trial ended early. It remains one of the strongest signals that treating a medical risk factor can protect thinking (see Blood Pressure and the Brain).

Multi-part lifestyle programs: FINGER and U.S. POINTER. The Finnish FINGER trial (published 2015) found that a two-year program combining exercise, healthy diet, brain training and health monitoring helped thinking in older adults at risk. The U.S. POINTER trial tested a similar approach in 2,111 sedentary Americans aged 60 to 79 with other risk factors. Both groups improved on thinking tests over two years. People in the structured program (regular coached meetings, set exercise and diet goals) improved slightly more than people who followed a self-guided plan. The benefit looked similar in people with and without the APOE4 gene. The difference was small, and the trial didn't measure whether it prevents dementia, but it supports the idea that healthy habits with accountability help.

Why prevention trials are hard

• They take years. Dementia develops slowly, so trials must run for years and enroll thousands of people.
• Finding the right people is costly. Until recently, finding people with silent amyloid required PET scans or spinal taps. Blood tests are making screening faster and cheaper (see Blood Tests for Alzheimer's).
• Small effects are hard to see. In people without symptoms, decline is slow, so trials need sensitive tests to detect any difference.
• Diversity has been limited. Most volunteers have been white and well educated, which makes it harder to know whether results apply to everyone.

Can I join a prevention trial?

Yes, many prevention studies need people without memory problems, including people with a family history of Alzheimer's and people with no special risk at all. Some trials will test your amyloid status as part of screening. Before joining, ask:

• Will I learn my amyloid or genetic test results, and what support is offered if I do?
• What are the possible side effects, such as ARIA with anti-amyloid drugs (see ARIA: Side Effects of Anti-Amyloid Drugs)?
• How many visits, scans and tests are involved, and is travel paid?

You can search for studies at ClinicalTrials.gov, and our guide to Joining a Clinical Trial explains how trials work and what protections volunteers have.

The bottom line

No drug has yet been proven to prevent Alzheimer's. The most solid evidence for lowering risk today comes from managing health factors such as blood pressure and from an active, healthy lifestyle (see Reducing Dementia Risk: The 14 Risk Factors). Several major drug prevention trials are under way, and their results over the next few years will show whether treating Alzheimer's before symptoms can keep people well longer.

Sources

1. Sperling RA et al. Trial of Solanezumab in Preclinical Alzheimer's Disease (A4 Study). New England Journal of Medicine, 2023
2. Baker LD et al. Structured vs Self-Guided Multidomain Lifestyle Interventions for Global Cognitive Function: The US POINTER Randomized Clinical Trial. JAMA, 2025
3. SPRINT MIND Investigators. Effect of Intensive vs Standard Blood Pressure Control on Probable Dementia. JAMA, 2019
4. Alzheimer's Association: U.S. POINTER Study
5. ClinicalTrials.gov (U.S. National Library of Medicine)

Not medical advice. This article is general information, not a diagnosis or treatment plan for any individual. Talk with a doctor about your situation.

Related articles

• Joining a Clinical Trial
• Dementia Research Today
• Reducing Dementia Risk: The 14 Risk Factors
• Biomarkers
• Amyloid and Tau Explained