Dementia researchers may need about 350,000 people to volunteer just to fill clinical trials that are already underway, according to the 2026 World Alzheimer Report, released around World Alzheimer's Day on Sept. 21. The report from Alzheimer's Disease International counts 158 potential therapies being tested in 192 trials worldwide, which together need about 55,000 participants.
The gap between those two figures is the heart of the problem. Strict eligibility and screening requirements mean many people who step forward never qualify, so recruiters must reach far more candidates than the number of spots they need to fill.
For U.S. families, that math lands close to home. An estimated 7.4 million Americans 65 and older are living with Alzheimer's in 2026, and nearly 13 million family members and friends provide unpaid care to people with Alzheimer's or other dementias, according to the Alzheimer's Association's 2026 Facts and Figures report. Many of those households will eventually weigh whether a trial is right for a loved one.
A Crowded Pipeline Meets a Recruitment Bottleneck
The report describes an unusually active moment for dementia research. Clinical trials have shown for the first time that new treatments can slow the progression of Alzheimer's disease. Still, Chris Lynch, acting chief executive of Alzheimer's Disease International, warned that "major barriers to recruiting trial participants risk slowing progress."
Disease-modifying drugs such as lecanemab and donanemab are designed to slow the disease rather than only ease symptoms. Blood tests for Alzheimer's-related changes are emerging, and computer-driven drug discovery is speeding up. Each advance still depends on people willing to be tested, monitored, and followed for months or years.
The report also notes that trials lack diversity because most are conducted in high-income countries with mostly white participants, which limits how well the findings apply to everyone.
Barriers often begin long before a person reaches a research center, according to a summary of the report's findings. Delayed diagnosis, limited access to specialist testing, travel costs, language barriers, and the need for a care partner can all keep people out.
Independent pipeline data point the same way. Dr. Jeffrey Cummings of the Kirk Kerkorian School of Medicine at UNLV, whose annual pipeline report tracks Alzheimer's drug development, counted 192 trials testing 158 drugs this year, up from 182 trials and 138 drugs in 2025.
Screening Rules Turn Willing Volunteers Away
Many dementia drug trials target a specific stage of disease. They commonly require evidence of Alzheimer's-related proteins through brain scans, spinal fluid, or blood tests, and they may exclude people with certain other health conditions or medications. Many also require a study partner who can attend visits and report on daily functioning.
Those rules protect the science by helping researchers learn whether a drug works in the people it is designed for, but they narrow the field quickly. Someone with memory complaints may learn after hours of testing that their symptoms are too mild, too advanced, or caused by something else.
The 350,000 figure is an estimate based on expected screening failures, not a count of open spots, and it covers trials worldwide rather than the United States alone. Joining a trial also does not guarantee access to an effective treatment, since some participants receive a placebo. The report does not change current medical guidance on diagnosis or care.
Women face a higher lifetime risk. At age 45, the lifetime risk of Alzheimer's is 1 in 5 for women and 1 in 10 for men, according to the Alzheimer's Association.
Where U.S. Families Can Search for Trials
The National Institute on Aging's Alzheimer's.gov Clinical Trials Finder lets families search for studies by location, and the institute's Alzheimer's and related Dementias Education and Referral (ADEAR) Center answers questions at 800-438-4380. People with memory problems, healthy volunteers, and caregivers can all take part in dementia research.
The federal registry ClinicalTrials.gov lists publicly and privately funded studies and can be searched by condition and location. The Alzheimer's Association's free TrialMatch service helps connect people with studies that may fit, and the association's helpline is 800-272-3900.
Families can also contact NIA-funded Alzheimer's Disease Research Centers at major medical institutions across the country. Some of these centers offer memory evaluations alongside research studies.
Before enrolling, families can ask how often visits occur, whether travel costs are reimbursed, what the chance of receiving a placebo is, and what happens when the trial ends. Study-related tests are often provided at no cost, and some studies offer compensation, though practices vary. It helps to involve the person's regular clinician and the care partner who will attend visits.
Caregivers carry much of the load. A trial can add travel, scheduling, and time away from work for the family member who serves as a study partner. Asking about remote visits, flexible scheduling, and transportation help before signing up can make participation more realistic for working families.
Findings from 29 mid-stage, or Phase 2, Alzheimer's trials are expected this year, according to Cummings' report. The central uncertainty is whether recruitment can keep pace with the pipeline. For families, the practical step is to learn the options early, before a crisis forces rushed decisions.
Key Questions Answered
What did the 2026 World Alzheimer Report find? It counted 158 potential therapies in 192 clinical trials worldwide, needing about 55,000 participants. Because many volunteers fail screening, an estimated 350,000 people may need to volunteer.
Why are so many volunteers turned away? Trials often require a specific disease stage, proof of Alzheimer's-related proteins, the absence of certain other conditions, and a study partner. Many people do not meet every requirement.
Who can join dementia research in the United States? People with memory problems, healthy volunteers, and caregivers can all take part in dementia research, according to the National Institute on Aging.
How can families find a trial near them? They can use the Alzheimers.gov Clinical Trials Finder, search ClinicalTrials.gov by condition and location, or use the Alzheimer's Association's TrialMatch service.
Does joining a trial mean getting a new drug? Not always. Some participants receive a placebo, and experimental treatments may not work. Families should discuss risks and benefits with the study team and a regular clinician.
Does the report change current Alzheimer's care guidance? No. The report focuses on research capacity and recruitment, not on diagnosis or treatment recommendations.
