A promising new study from the Knight Family DIAN-TU research group at Washington University School of Medicine has found that starting Alzheimer’s treatment years before symptoms begin could delay — and possibly even prevent — the disease.
The study focused on people with rare genetic mutations that almost guarantee they will develop Alzheimer’s in middle age, often in their 30s, 40s, or 50s.
The results, published March 19 in The Lancet Neurology, mark the first time a clinical trial has shown that removing amyloid plaques from the brain well before symptoms appear can reduce the risk of Alzheimer’s dementia. Amyloid plaques are clumps of a protein that build up in the brains of people with Alzheimer’s and are believed to be an early cause of the disease.
The international study included 73 people from families with inherited forms of Alzheimer’s. A subgroup of 22 participants, who showed no signs of cognitive problems when the study began and who received the treatment the longest (an average of 8 years), saw their risk of developing symptoms cut in half — from nearly 100% to about 50%.
“This is a major step forward,” said senior author Dr. Randall Bateman. “These people were all expected to develop Alzheimer’s, but some of them haven’t — even though they’ve reached or passed the age when their symptoms should have started.”
The treatment used in the trial was gantenerumab, an anti-amyloid drug. Though it is no longer being developed due to disappointing results in later-stage trials, it proved helpful in this study when given early and long-term.
The idea is based on the amyloid hypothesis, which suggests that amyloid buildup is the first stage in the development of Alzheimer’s, and that removing or preventing this buildup can stop the disease before it starts.
Participants in this trial had already taken part in the earlier DIAN-TU-001 study, the world’s first Alzheimer’s prevention trial, launched in 2012.
All participants were within 15 years before or 10 years after their expected age of symptom onset, based on family history. While earlier studies showed gantenerumab reduced amyloid in the brain, researchers hadn’t seen clear cognitive benefits — likely because symptoms hadn’t yet begun.
To continue investigating whether longer treatment could help prevent dementia, the team launched an open-label extension, allowing participants to keep taking the drug.
Though the extension was planned for three years, it was cut short in 2023 when Roche/Genentech, the drug’s developers, stopped working on gantenerumab after other trials failed. Still, participants had received an average of 2.6 years of treatment in the extension — and some for much longer.
In the group treated the longest, the effect was striking: the risk of developing symptoms was reduced by 50%. The researchers used statistical models that not only measured who developed symptoms, but also when they developed them, compared to their expected age.
If more participants continue to stay healthy past their expected onset age, the protective effect could turn out to be even stronger.
However, the drug was not without side effects. A condition called ARIA, which involves tiny spots of bleeding or brain swelling seen on brain scans, occurred in about 30% of participants — higher than in earlier trials.
In most cases, it caused no symptoms and went away on its own, but two people had to stop taking the drug due to serious cases. There were no deaths or life-threatening side effects.
Because gantenerumab is no longer in development, many participants are now receiving lecanemab, another anti-amyloid drug that was approved by the FDA in 2023. The researchers are also planning future trials and have submitted a request for funding from the National Institutes of Health.
Although this study focused on people with rare, inherited forms of Alzheimer’s, researchers believe the findings could apply more broadly. In both inherited and more common forms of Alzheimer’s, amyloid buildup starts about 20 years before memory problems begin.
If similar results are seen in people with the more typical, late-onset Alzheimer’s, early treatment could potentially help millions of people.
Dr. Bateman remains hopeful. “This could be the first clinical evidence that shows Alzheimer’s prevention is possible. One day, we may be able to delay or prevent Alzheimer’s for millions around the world.”
New trials are already underway, including the DIAN-TU Primary Prevention Trial, which is testing a new drug, remternetug, in people as young as 18 who are years away from any signs of Alzheimer’s. The goal is to see whether stopping the disease even earlier — before any brain changes are detectable — can stop it from developing at all.
The Alzheimer’s Association, which is helping fund the research, is calling the results “genuinely unprecedented and groundbreaking.” They hope this work will lead to a new era of Alzheimer’s prevention, rather than treatment after symptoms begin.
In summary, this study suggests that the earlier you intervene in Alzheimer’s disease, the better. Starting treatment before memory loss begins — and sticking with it long-term — may be the key to delaying or even preventing the disease altogether.
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The research findings can be found in The Lancet Neurology.
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