A new international study has offered hope that Alzheimer’s disease may one day be preventable—at least in people genetically destined to develop it. The research, published in The Lancet Neurology, shows that treating individuals at high risk for early-onset Alzheimer’s with an experimental drug significantly delayed the development of symptoms.
The study was led by the Knight Family Dominantly Inherited Alzheimer Network-Trials Unit (DIAN-TU), based at Washington University School of Medicine in St. Louis, and involved 73 people with rare, inherited gene mutations that lead to Alzheimer’s in their 30s, 40s, or 50s.
These mutations cause excessive buildup of amyloid plaques in the brain, a key feature of Alzheimer’s disease.
The most striking results came from a group of 22 participants who had no cognitive symptoms at the start and who received the anti-amyloid drug gantenerumab for the longest time—an average of eight years.
In this group, the risk of developing Alzheimer’s-related symptoms dropped from nearly 100% to about 50%. This suggests that early and long-term removal of amyloid plaques may delay, or possibly prevent, the onset of dementia.
Dr. Randall J. Bateman, senior author of the study, said, “Everyone in this study was destined to develop Alzheimer’s disease, and some of them haven’t yet. We don’t know how long they’ll stay symptom-free—maybe years, maybe decades—but this proves it’s possible to delay the disease.”
These findings support the amyloid hypothesis—the idea that amyloid buildup triggers the brain changes that eventually cause Alzheimer’s. Removing amyloid early might interrupt this chain of events, delaying or stopping memory loss and other symptoms.
The research builds on earlier work from the same group, which launched the first Alzheimer’s prevention trial (DIAN-TU-001) back in 2012. In the initial phase, researchers tested gantenerumab and found it lowered brain amyloid but didn’t show clear cognitive benefits—likely because the participants had not yet begun to decline.
That led to an open-label extension, where everyone received the drug, allowing scientists to monitor longer-term effects.
However, the extension was cut short in 2023 after Roche/Genentech, the maker of gantenerumab, ended its development due to disappointing results in other trials. Still, by that point, some participants had been taking the drug for over eight years, giving researchers a unique chance to study its long-term effects.
Importantly, the benefit was only statistically significant for those treated the longest. Shorter treatment—just two to three years—did not appear to impact cognitive decline.
While gantenerumab is no longer being developed, its story is far from over. Other similar drugs, such as lecanemab, have been approved for use in patients with early Alzheimer’s symptoms and are now being tested in prevention trials.
Many of the participants in the gantenerumab trial have since switched to lecanemab, and researchers are continuing to monitor their progress.
The study also reported some side effects. Around 30% of participants experienced amyloid-related imaging abnormalities (ARIA), which show up as small brain bleeds or swelling on brain scans.
While most cases were mild and temporary, two people had more severe reactions that required stopping treatment. No deaths occurred, and the overall safety profile was similar to past trials.
To take the research even further, the Knight Family DIAN-TU has launched a Primary Prevention Trial using another anti-amyloid drug called remternetug, made by Eli Lilly. This study is enrolling people as young as 18—long before any brain damage has begun—to see if even earlier treatment could stop Alzheimer’s before it starts.
Though the current study focused on people with a rare genetic form of Alzheimer’s, the implications could extend to the broader population. Both early-onset and late-onset Alzheimer’s involve amyloid buildup that begins years before symptoms appear.
So if anti-amyloid treatments prove successful in this group, they might work for the millions of people at risk of late-onset Alzheimer’s as well.
Dr. Maria Carrillo of the Alzheimer’s Association called the findings “genuinely unprecedented and groundbreaking,” and emphasized the need for continued, accelerated research. The Alzheimer’s Association has invested heavily in this area and hopes these early results can be expanded through new trials.
Review and Analysis
This study marks an important milestone in Alzheimer’s research: it offers the first real clinical evidence that early, long-term treatment to remove brain amyloid could delay the onset of dementia. While the sample size was small and limited to people with genetic mutations, the findings support decades of research pointing to amyloid as a key target in Alzheimer’s disease.
The most significant limitation is that the drug used—gantenerumab—is no longer available for clinical use. However, similar drugs like lecanemab are already FDA-approved and in use, and newer treatments are being explored.
The key takeaway is that timing matters. Anti-amyloid treatment may only be truly effective when given years before symptoms appear. For people already showing signs of cognitive decline, the impact is more limited.
Looking ahead, prevention trials in younger individuals—before amyloid buildup even begins—will be crucial to answering the ultimate question: can Alzheimer’s disease be stopped before it starts?
For now, the results offer hope. They suggest that with the right treatment, started early enough, Alzheimer’s may not be an inevitable part of aging—even for those born with a genetic fate.
If you care about brain health, please read studies about vitamin D deficiency linked to Alzheimer’s and vascular dementia, and extra-virgin olive oil could boost brain function.
For more information about brain health, please see recent studies about antioxidants that could help reduce dementia risk, and strawberries could help prevent Alzheimer’s disease.
The research findings can be found in The Lancet Neurology.
Copyright © 2025 Knowridge Science Report. All rights reserved.
