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.
