People living with Alzheimer’s disease in the UK are being locked out of experimental treatments because they are not diagnosed early enough – or with enough precision – to qualify for clinical trials, according to Alzheimer’s Research UK. The charity’s warning comes as the number of drug trials worldwide reaches a record high, raising the stakes for a diagnostic system that one recent report described as “appalling” and “broken”.
Diagnosis delays leave patients behind
Getting a diagnosis for Alzheimer’s can take years. Alzheimer’s Research UK notes that one in three people in the UK with the condition do not have a formal diagnosis at all. A report from September 2025 found that nearly one in three people wait more than a year for a formal dementia diagnosis, with memory clinic waiting times sometimes stretching beyond two years. Another report from the same period revealed that one in five individuals were still waiting more than two years for a diagnosis after first seeing their GP.
Even when a diagnosis is made, it is often too vague to be useful for clinical trial enrolment. Many patients are labelled simply with “dementia” rather than a specific Alzheimer’s diagnosis, meaning researchers cannot match them to studies that target the underlying disease mechanisms. The consequences are stark: fewer than 1,000 UK patients are currently taking part in Phase 3 trials for Alzheimer’s drugs. By comparison, in September 2022 Alzheimer’s Research UK reported that only 61 participants were recruited to late-stage dementia drug trials in England in the previous year – a figure far lower than for other major health conditions.
Dr Sheona Scales, director of research at Alzheimer’s Research UK, said the recent surge in clinical trials was driving demand for participants, but without a large and diverse patient pool the UK risked missing out entirely. “People won’t have access to the next generation of Alzheimer’s treatments,” she warned. “Progress depends on finding the right participants for these studies, and that starts with early and accurate diagnosis. Without it, researchers can’t match people to the trials most likely to help them.”
Record number of trials, but a narrowing window
Globally, the landscape for Alzheimer’s drug development has shifted significantly. Dr Jeffrey Cummings of the University of Nevada has published an annual review of clinical trials for Alzheimer’s drugs for the past decade. His latest review, published in Alzheimer’s & Dementia: Translational Research & Clinical Interventions, found that the number of candidate drugs being trialled has risen by 40% over the past ten years, with 158 potential medicines and 192 trials taking place worldwide this year. Eight final Phase 3 trials are due to end in 2026. Cummings’ 2025 annual report counted 182 active clinical trials globally, assessing 138 drugs.
The review also reveals a shifting approach to the disease. While anti-amyloid medicines such as lecanemab and donanemab have been hailed as a crucial breakthrough – showing that directly targeting the disease’s process can slow decline – the pipeline is now diversifying. Fewer drugs are designed simply to remove amyloid; more are targeting tau, inflammation and other immune system pathways. “Anti‑amyloid medicines such as lecanemab and donanemab have been a crucial breakthrough,” Cummings said. “They’ve shown that directly targeting the disease’s process can slow decline. But they are only the beginning of what people with Alzheimer’s will ultimately need.”
One keenly watched trial that could report this year is the Trailblazer-Alz 3 study, which is testing the effect of donanemab in people who have amyloid in the brain but no Alzheimer’s symptoms. This could show whether the drug can protect against cognitive decline by being administered before the disease destroys brain cells – a scenario that depends entirely on early detection.
Why early and accurate diagnosis is the gateway to trials
The precise mechanisms that drive Alzheimer’s remain unclear, but hallmarks include the buildup of abnormal proteins in the brain: amyloid plaques between cells and tangles of tau protein inside neurons. Anti-amyloid drugs like lecanemab and donanemab have been approved by medicines regulators around the world, and clinical trials found that both slowed disease progression. However, the benefits were slight, and neither drug was considered cost-effective for the NHS by the National Institute for Health and Care Excellence (NICE), which ruled that their benefits were too small to justify the cost. NICE is now reconsidering these decisions following appeals from the manufacturers, and new cost-effectiveness thresholds agreed as part of a UK-US trade deal will apply. The estimated cost for these drugs in the US is around $32,000 per year.
The drugs are most effective in the earliest stages of Alzheimer’s, making early and accurate diagnosis not just desirable but essential. A recent Cochrane review of seven anti-amyloid drugs prompted controversy by concluding that the class had no clinically meaningful impact over 18 months. But critics argued that the analysis lumped lecanemab and donanemab in with older, less effective medicines, and said the drugs may have better results when given to patients much earlier and for longer periods. In other words, the window for meaningful benefit narrows the later diagnosis occurs.
Yet the UK’s diagnostic capacity is severely constrained. Current gold-standard tests – lumbar punctures and PET scans – are costly and invasive. The UK has a significantly lower number of PET scanners per capita compared to Germany and the US. A September 2025 report described the diagnostic system as “appalling”, “shameful” and “broken”, with many individuals left to come to terms with their diagnosis alone. Barriers include a lack of up-to-date patient records and data access problems affecting screening. Research is not routinely embedded in Alzheimer’s care, further hindering trial recruitment. An investment of £14 billion over ten years has been estimated as necessary to bring the UK up to the G7 average for Alzheimer’s specialists and PET and MRI scanners, which could reduce average wait times by around 87%.
Charity’s call to action: a push for faster and more accessible diagnostics
Alzheimer’s Research UK has invested significantly in drug discovery, renewing its Drug Discovery Alliance with up to £45 million of new investment over five years, supporting centres at Cambridge, Oxford and UCL. But the charity stresses that without a matching investment in diagnosis, the UK will fail to reap the rewards. There is a push to develop faster and more accessible diagnostic methods, particularly blood tests. The UK government has launched a £5 million challenge to develop technological solutions for speeding up dementia diagnosis by 2029, aiming for over 92% of patients to be diagnosed within 18 weeks of referral.
Scales reiterated the urgency: “Without a large and diverse range of patients to match to trials, the UK risks missing out on the next generation of Alzheimer’s treatments.” The message is clear: the science is advancing, but the diagnostic system must catch up – or patients will be left behind.