With a record 192 clinical trials assessing 158 potential dementia treatments underway globally, researchers face a critical shortage of trial participants to advance this expanding pipeline. The World Alzheimer Report 2026, released by Alzheimer’s Disease International (ADI), highlights that roughly 55,000 volunteers are essential to sustain these studies at current levels.
Current Alzheimer’s research typically demands biological proof of amyloid or tau pathology, meaning most individuals screened are ineligible. University of Nevada professor Jeffrey Cummings estimates that with screen-failure rates of at least 70 per cent, approximately 350,000 screenings would be required to recruit 55,000 trial participants.
Dementia Research Pipeline
The pipeline has expanded from 182 trials and 138 therapies the previous year. Chris Lynch, ADI’s interim chief executive, stated: “This is a moment of real hope for dementia research. After decades of frustration, clinical trials have shown for the first time that new treatments can slow the progression of Alzheimer’s disease, and a burgeoning pipeline of treatment trials brings real hope.”
Lynch noted that each new diagnostic tool or treatment relies on volunteers, and that “very low awareness of trials and a flawed referral process from doctors and specialists not only risk slowing down progress but can deny people their right to participate in trials.” Amyloid-directed agents, such as lecanemab and donanemab, now make up only around one fifth of the pipeline, with roughly three-quarters of drugs aimed at other mechanisms.
Repurposed medicines account for 56 agents, about 35 per cent of the total, and their established safety profiles tend to speed progress. Combination strategies are appearing too, including a Phase 2 study pairing a tau vaccine with an anti-amyloid treatment. Meanwhile, TRAILBLAZER-ALZ 3, an ongoing Phase 3 clinical trial by Eli Lilly, is asking whether treating the earliest biological stage of disease can alter its course before symptoms develop.
Screening and Participation
Screening has traditionally depended on PET imaging or lumbar puncture, which limits the number of willing volunteers. Plasma biomarkers, such as p-tau217, could alter this situation. Professor Colin Masters suggests that dementia care should follow oncology’s lead, where trial participation is often standard. In contrast, only 551 people were enrolled in late-stage dementia trials in England during the most recent five-year period, compared to 24,000 for cancer.
Jim Taylor, president of Voices of Alzheimer’s, contends that eligibility criteria have become excessively restrictive, excluding individuals with prevalent conditions like cardiovascular and metabolic diseases. The report indicates this is both a scientific and an ethical issue, as roughly 90 per cent of research participants are non-Hispanic white, potentially compromising biomarker accuracy in other groups.
Professor Sid O’Bryant notes that biomarkers behave differently across populations, so blood tests validated in one group may be less accurate in another. For example, APOE4, a common genetic risk factor, carries a significantly lower statistical risk in people of African ancestry than in those of European or East Asian descent.
The report highlights the need for better targeting of rural populations, where most research and clinical trials are not currently targeted. Community-based advertising, such as town hall meetings, could be a productive way to raise awareness and recruit participants from these regions. Bill Yeates, an ADI board member diagnosed with young-onset Alzheimer’s disease, said: “Taking part was about being part of something much bigger than myself and helping create a future where others living with dementia might have access to better treatment options.”
Private spending on clinical-stage Alzheimer’s research and development between 1995 and 2021 is estimated at $42.5 billion, while the World Health Organization put the global cost of dementia at US$1.3 trillion in 2019, roughly half of it attributable to informal carers. The report’s ten recommendations ask governments to invest in diagnostic capacity and create incentives for trials in underserved regions.
Professor Craig Ritchie, chief executive of Scottish Brain Sciences, said: “We are entering one of the most important periods in the history of brain health research. For the first time, there is a growing pipeline of treatments and tests that have the potential to detect and then delay, slow, and perhaps even prevent Alzheimer’s disease.” The report notes that every person who takes part in research helps to bring the next generation of tests and treatments closer, with 94 per cent participant retention achieved in Colombia’s Alzheimer’s Prevention Initiative trial of crenezumab by year four.
Increasing Participation
Researchers are working to reduce the burden on participants, making it easier for people to take part in clinical trials. This includes simplifying the screening process and reducing the number of visits required. By making clinical trials more accessible, researchers hope to increase participation and accelerate the development of new treatments.
Global Distribution of Clinical Trials
Almost half of recorded active Alzheimer’s drug trial sites are in North America. Western Europe and Israel host a significant number of trial sites. Latin America and South Africa, Australia, and New Zealand have fewer trial sites.
More than 60 million people live with dementia globally. A large proportion of people with dementia live in low- and middle-income countries. This proportion is expected to increase by 2050.
Clinical trials can build capacity even when a drug fails. Training staff and expanding diagnostic capacity are examples of this. Participant retention can also be achieved through successful trial management.
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