Alzheimer’s Clinical Trials Explained

Clinical trials are vital for testing the safety and effectiveness of dementia treatments. Whether you have a diagnosis, carry a genetic risk factor, or simply want to contribute to research with a healthy brain, there may be a trial that fits your situation. Here’s what you need to know before you decide to get involved — from the different types of studies to what participating in a trial actually looks like day to day.

What is an Alzheimer’s clinical trial?

A clinical trial is a research study involving human volunteers designed to expand medical knowledge about a disease. In Alzheimer’s and dementia research, trials fall into two broad categories: observational studies and interventional trials.

Observational studies aim to understand what happens to participants in different real-world situations. You typically continue your daily routine and existing medical treatments as researchers gather data about patterns and outcomes. 

Interventional trials test a specific treatment, lifestyle change, or diagnostic tool. Participants are randomly assigned to either a test group (which receives the experimental intervention) or a control group (which receives a placebo, or inactive substitute). The research team compares the results of the two groups.

What are the four types of Alzheimer’s clinical trials?

Interventional trials in Alzheimer’s research generally fall into four categories, each with a different scientific goal.

Drug trials: Testing new medications

Drug trials evaluate whether a potential medication is safe and effective at preventing or treating Alzheimer’s disease. Drug trials go through multiple phases before approval, each phase involving more clinical trial participants. 

For instance, Eli Lilly’s donanemab, a drug that targets amyloid plaques in the brain associated with Alzheimer’s received FDA approval in July 2024 after trial data showed it reduced amyloid burden in a significant number of patients within six months, and in roughly half of participants within 12 months.

Lifestyle trials: Can exercise or diet promote brain health?

Lifestyle trials investigate whether changes in daily habits — exercise, diet, sleep, social engagement — can reduce dementia risk or slow cognitive decline. 

U.S. POINTER, the largest randomized trial to examine the protective effects of healthy behaviors on brain health, found that a healthy diet, exercise and social interactions, along with coaching and medical guidance, can improve brain health. 

The structured group in the study followed a weekly plan of eight exercise sessions among other healthy behaviors like eating a balanced diet. They also attended 38 team meetings with other participants and facilitators of the study. The trial’s “unstructured program” followed a self-guided approach where participants were encouraged to exercise and eat healthy, but only attended six team meetings. Both groups showed a rise in global cognitive function, and, at the end of the two year period, the people in the structured group had cognitive scores similar to those of people one to two years younger.

Lifestyle trials offer a way for people at any stage — including healthy adults — to participate in dementia research and potentially benefit from the intervention itself.

Prevention trials: Looking for ways to stop Alzheimer’s before it starts

Prevention trials test interventions aimed at stopping Alzheimer’s from developing in people who are at risk but don’t yet have symptoms. One such trial, the Primary Prevention Trial, is focused on people who carry certain rare genetic mutations that put them highly at-risk of developing early-onset Alzheimer’s disease. People who carry the genes APP, PSEN1, and PSEN2 can begin showing symptoms in their 30s or 40s. 

The trial is enrolling about 240 young adults between ages 18 to early 30s who have a family member carrying APP, PSEN1, or PSEN2. 

Hannah Richardson, 24, a trial participant with an extensive family history of Alzheimer’s, said, “I knew immediately I wanted to be a part of it.”

Richardson said she hopes to see a personal benefit, “but even if that is not the outcome, just collecting this data is still so important for helping people down the line not suffer the way that people are suffering now.”

Diagnostic trials: Searching for earlier, easier ways to detect Alzheimer’s

Diagnostic trials aim to validate new testing methods that could identify Alzheimer’s disease earlier, less invasively, and at lower cost than current tools like PET scans and lumbar punctures. 

Professor Maya Koronyo-Hamaoui at Cedars-Sinai Medical Center is researching whether retinal scans — scans of the back of the eye — could serve as a window into the brain’s health. Because the retina is the only part of the central nervous system not protected by bone, it can be imaged directly and repeatedly, making it a promising candidate for non-invasive Alzheimer’s screening.

What are the different clinical trial phases?

Each phase of a clinical trial gathers more information about safety and efficacy that is taken into account by the Food and Drug Administration (FDA) in the U.S., which decides whether to approve new drugs for the general public. Most drug trials move through three phases before a treatment can be considered for regulatory approval:

Phase 1: This phase focuses on safety and is the earliest trial for any medical intervention. A small group of roughly 20 to 80 volunteers receives the experimental treatment, and researchers monitor for side effects. This phase typically lasts up to a year.

Phase 2: This phase provides information about both effectiveness and dosages. With 100 to 300 participants, researchers begin evaluating whether the drug actually does what it’s supposed to do — usually over several months to two years.

Phase 3: This phase tests whether a drug is effective in a larger cohort of participants with Alzheimer’s. Trials at this stage involve 300 to 3,000 participants and may span multiple years. The goal is to compare the new treatment against existing options and build the robust safety and efficacy data required for FDA review.

If a trial succeeds at each phase, it advances to the next — with progressively larger groups and longer timelines.

Do all participants receive the experimental treatment?

Most interventional trials are double-blind, meaning neither participants nor researchers know who is in the test group and who is in the control group receiving a placebo. This structure is essential for producing unbiased results.

If you end up in the control group, that doesn’t mean you’re left out of any benefit. If the trial succeeds and the treatment is approved, control group participants typically receive priority access to the new therapy.

What should I consider before joining an Alzheimer’s trial?

If you’re considering joining a clinical study, it’s important to note that there are some risks to participating in any study. As a participant, you may invest significant time and still not receive the treatment. You could also experience side effects. The decision to participate in a trial is deeply personal, and you should feel empowered in either decision you make. 

Carol Cary was diagnosed with Alzheimer’s in 2023 and decided to enroll in the trial for donanemab (Kisunla).

“This drug was not available yet, and I was willing to step up and be a guinea pig if need be,” she said. “I don’t know of anything else I could do. I wasn’t going to sit by and let this happen. I told myself I’m gonna go out there and look for something that at least shows some promise and is within reach.”

Before enrolling, here are some practical questions worth considering:

Eligibility: Each trial has specific criteria related to age ranges, disease status (diagnosed, at-risk, or healthy), preexisting health conditions, and sometimes genetic markers. Check whether you meet the requirements.

Requirements: Some trials require regular clinic visits, cognitive testing, blood draws, or imaging. Others may be largely remote. Typically, participants are reimbursed for any costs incurred, such as the cost of procedures during the screening process or travel to sites. Read the protocol carefully so you have a full understanding of what participation will look like.

Logistics: Consider where the trial is located and whether travel is manageable. Some larger trials have multiple sites, which can make participation more feasible. Many trials require a study partner, and you will need to ensure your study partner has the time and availability required.

Time commitment: Alzheimer’s trials can run from months to several years. Make sure the timeline fits your life before you commit.

Looking ahead, the Alzheimer’s research landscape is moving faster than at any point in history — with newly approved drugs, emerging diagnostic tools like retinal scans, and a growing body of evidence about lifestyle’s role in brain health. 

By participating in a trial, you can play a role in moving potentially monumental treatments for Alzheimer’s disease forward. If you’re considering trial participation, talk to your doctor or another medical professional about what participation looks like.