The dementia drug pipeline stands at its largest scale ever, yet a shortage of trial participants could stall progress unless eligibility rules are loosened and recruitment improves. The World Alzheimer Report 2026, published by Alzheimer’s Disease International (ADI) on September 21, identifies 158 potential therapies in 192 clinical trials worldwide. The report warns that 55,000 participants are needed to keep these studies running, with eight Phase III trials scheduled to reach completion this year.
Modern Alzheimer’s trials typically require biological confirmation of amyloid or tau pathology, and most people screened do not qualify. Professor Jeffrey Cummings of the University of Nevada, whose annual pipeline review supplies the report’s headline figures, estimates that with screen-failure rates of at least 70 per cent, about 350,000 screens would be needed to produce 55,000 trial participants. The pipeline has grown from 182 trials and 138 therapies a year earlier.
Chris Lynch, ADI’s acting chief executive, said: “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.” He 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.”
The report treats lecanemab and donanemab (anti-amyloid monoclonal antibodies used to treat early-stage Alzheimer’s disease), now approved in several countries, as a first step rather than an endpoint. Therapies of this class slow clinical decline by about 30 per cent, an effect some scientists have judged underwhelming. A 2025 Bayesian meta-analysis cited in the document concluded that whether amyloid clearance reliably predicts clinical improvement is still unresolved.
Broadening Treatment Targets
What has changed is the breadth of what is being tested. Amyloid-directed agents now make up only around one fifth of the pipeline, with roughly three-quarters of drugs aimed at other mechanisms such as inflammation, vascular dysfunction and cellular ageing. Anti-inflammatory approaches have risen from 6 per cent of trials in 2016 to around 18 per cent. 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. None of this is cheap. Private spending on clinical-stage Alzheimer’s research and development between 1995 and 2021 is estimated at $42.5bn, 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.
Bridging the Screening Gap
Screening has historically relied on PET imaging or lumbar puncture, which narrows the pool of willing volunteers. Plasma biomarkers, such as p-tau217, may change this. Cummings suggests that if blood tests were used early, there would be many negative results, but the remaining screening steps would have a much higher yield. Professor Colin Masters, the Australian neuroscientist whose work helped establish the amyloid hypothesis, argues that dementia care should borrow from oncology, where entering a trial is often routine. The contrast is huge.
Dr Fiona Carragher, chief executive of Kidney Research UK and formerly of the Alzheimer’s Society, told the report’s author that 551 people were recruited to late-stage dementia trials in England over the most recent five-year period, against 24,000 for cancer. Late or non-specific diagnosis is a large part of the reason. Many patients are never told which form of dementia they have, and have not had the specialist testing that would show they qualify. Jim Taylor, president of Voices of Alzheimer’s, adds that eligibility criteria have become overly restrictive. In his view they exclude people with the cardiovascular and metabolic conditions that are common in the populations most affected by dementia.
Of the 6,763 recorded active Alzheimer’s drug trial sites, almost half (3,156) are in North America. Western Europe and Israel host 1,363, while Latin America has 321 and South Africa, Australia and New Zealand together have 175. Yet more than 60 million people live with dementia globally, a figure projected to surpass 139 million by 2050. More than 60 per cent already live in low- and middle-income countries, a share expected to exceed 70 per cent by 2050. The report argues that this is a scientific problem as well as a fairness one.
Professor Sid O’Bryant of the University of North Texas Health Science Center notes that around 90 per cent of participants in the research that produced the ATN biomarker framework were non-Hispanic white. His own work suggests biomarkers behave differently across populations, so blood tests validated in one group may be less accurate in another. For example, APOE4, the strongest common genetic risk factor, carries a significantly lower statistical risk in people of African ancestry than in those of European or East Asian descent, a point Professor Zul Merali raises in the report’s Kenyan case study.
Expanding Reach Beyond Urban Centers
Capacity can be built even when a drug fails. Colombia’s Alzheimer’s Prevention Initiative trial of crenezumab missed its primary endpoint, yet it trained staff, expanded diagnostic capacity and achieved 94 per cent participant retention by year four. Rural reach and the cost of taking partADI emphasises that barriers begin long before anyone reaches a research centre. Delayed diagnosis, limited access to specialist testing, travel costs, language barriers and the need for a care partner to attend can all keep people out of consideration.
Merali, founding director of the Aga Khan University’s Brain and Mind Institute in Nairobi, said: “In Kenya and across other parts of sub-Saharan Africa, the majority of the population lives in rural areas, yet most research and clinical trials are targeted towards urban populations.” He commented that “better targeting of these populations, alongside practical support such as transportation to urban clinical trial centres, could significantly increase the recruitment and participation of appropriate populations.” Community-based advertising such as town hall meetings, he said, “could be a very productive way to raise awareness and recruit participants from rural regions.” Participation is also personal.
Bill Yeates, an ADI board member who was diagnosed with young-onset Alzheimer’s in 2019, joined a clinical trial in Australia, describing it as “being part of something much bigger than myself.” Yeates’ involvement reflects a broader reality: without volunteers, the pipeline risks stalling before treatments reach those who need them most.
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