Every approved medical treatment — every drug, every therapy, every preventive intervention — began as a clinical trial. They are the mechanism through which medical science moves from hypothesis to human benefit.
In the context of Alzheimer's prevention, clinical trials are especially critical. Because prevention research targets people who don't yet have symptoms, it requires large numbers of healthy volunteers who are willing to participate before they feel any reason to. That participation is an act of generosity that has direct implications for millions of people.
Here's what you need to know.
What Are the Phases of a Clinical Trial?
Clinical trials move through four phases, each designed to answer specific questions:
Phase 1 tests safety. A small group of participants receives the investigational treatment to identify side effects and determine safe dosage ranges.
Phase 2 tests efficacy and continues safety monitoring. Researchers assess whether the treatment appears to work as intended.
Phase 3 is the large-scale validation phase. Hundreds or thousands of participants are enrolled to confirm efficacy, monitor side effects, and compare the treatment against existing options or placebo. The TOMMORROW study was a Phase 3 trial.
Phase 4 occurs after approval, monitoring long-term safety and effectiveness in the general population.
What Does Participation Actually Involve?
This varies considerably depending on the study. Some trials require periodic clinic visits for cognitive assessments, blood draws, or neuroimaging. Others involve taking an investigational medication or placebo over months or years. Some focus purely on observation — tracking cognitive health over time without any intervention.
Before enrolling, participants go through a process called informed consent, where the study team explains all risks, benefits, requirements, and rights in detail. Participation is always voluntary, and participants can withdraw at any time.
How Do You Find Out If You're Eligible?
Eligibility criteria differ by trial. Common factors include age, cognitive health status, family history of Alzheimer's, genetic profile, and the absence of certain health conditions or medications.
The best starting points are:
Your physician. A primary care doctor or neurologist can assess your cognitive health and refer you to appropriate research programs.
ClinicalTrials.gov. The U.S. government's official registry of clinical studies lists thousands of active trials, searchable by condition, location, and status.
The Alzheimer's Association TrialMatch. A free, personalized matching service connecting individuals to relevant clinical trials.
Our Get Involved page. Register your interest through Tommorrow Study Collective and our team will help connect you with relevant research opportunities.
Why It Matters
Alzheimer's prevention trials need participants who are cognitively healthy today. If you are in your 50s or 60s and have never thought about participating in a clinical trial, this is the moment to start. The research being conducted right now will determine what treatments are available for the next generation — and potentially for you, years from now.
