By Sally Macdonald
A new wave of Alzheimer’s treatments is offering unprecedented hope, with one leading drug shown to delay the progression of the disease by up to four years—and in some cases, even improve cognitive function.
Lecanemab, a drug recently licensed for use in the UK, is part of a groundbreaking class of treatments aimed at clearing amyloid plaques from the brain, considered one of the key markers of Alzheimer’s disease. While previous trials showed the drug slowed disease progression by around six months over 18 months, new long-term data have revealed far more promising results.
In a four-year trial involving 478 patients, lecanemab delayed progression of the disease by an average of 11 months. Even more remarkably, 69% of participants with lower levels of the protein tau—another indicator of Alzheimer’s—showed no cognitive decline at all during the study. Of these, 56% actually improved their cognitive scores.
“This is about the time saved,” said Professor Christopher Van Dyck, director of the Alzheimer’s Research Unit at Yale School of Medicine and lead investigator on the study. “You will get worse over time, but it will take longer to get there. Early treatment clearly offers the greatest benefit.”
These findings were presented this week at the Alzheimer’s Association International Conference in Toronto, sparking excitement among researchers and medical professionals. Experts say it strengthens the case for early diagnosis and treatment, with hopes that such drugs could eventually be used preventively in high-risk patients.
Lecanemab, marketed as Leqembi, is one of several promising treatments now emerging. It targets the amyloid plaques that build up in the brains of people with Alzheimer’s, causing memory loss and cognitive decline. Traditionally, patients with mild dementia experience a one-to-two-point increase in cognitive decline scores each year. However, those treated with lecanemab saw just a 1.75-point increase over four years—a substantial slowing of progression.
A similar drug, donanemab, has also shown positive results. Although it’s usually administered for 18 months or until amyloid is cleared, a new study tracking patients for three years (including after treatment stopped) found they experienced delays in disease progression of between six and twelve months.
“These findings offer renewed hope that treatments can meaningfully change the course of Alzheimer’s—not just slow it for a short period,” said Dr. Sheona Scales, Director of Research at Alzheimer’s Research UK.
She noted that some patients on lecanemab for four years maintained cognitive performance, and in some cases even improved—particularly those treated early with lower levels of tau.
“This is the first wave of disease-modifying treatments for Alzheimer’s,” Dr. Scales said. “It’s encouraging, but there are still many questions, especially around what happens when treatment ends and whether the brain maintains its gains.”
Meanwhile, a third drug, called trontinemab, could be a breakthrough. Designed to clear amyloid plaques more efficiently while reducing side effects, early data suggests it could outperform both lecanemab and donanemab. Crucially, trontinemab appears to avoid the brain swelling side effects that have complicated the use of existing drugs.
Because of its lower risk profile, trontinemab could potentially be offered more broadly and at a lower cost, making it easier for national health services like the NHS to fund and distribute. Current Alzheimer’s treatments require intensive monitoring, including brain scans, which limits accessibility.
Around one million people in the UK live with dementia, with Alzheimer’s accounting for the majority of cases. While these new therapies do not offer a cure, they mark a significant shift in how the disease is managed—and raise the possibility of transforming long-term outcomes for patients.
As evidence mounts, experts are urging policymakers to keep pace with science. “It’s vital we continue to evaluate the potential benefits of these treatments and ensure that people with Alzheimer’s can access them as early as possible,” said Dr. Scales.
