A new study has found that an experimental drug may delay the onset of Alzheimer’s-related dementia in people who are almost certain to develop the disease in middle age due to inherited gene mutations.
This is the first clinical trial to show that removing amyloid plaques from the brain early—years before symptoms start—can significantly lower the risk of developing dementia.
The study was led by the Knight Family Dominantly Inherited Alzheimer Network-Trials Unit (DIAN-TU) at Washington University School of Medicine and was published in The Lancet Neurology on March 19.
The international trial involved 73 participants with rare genetic mutations that cause a buildup of amyloid in the brain. These mutations guarantee that they will develop Alzheimer’s disease, usually in their 30s, 40s, or 50s.
In a subgroup of 22 people who began treatment early and continued it for an average of eight years, the experimental drug reduced their risk of developing dementia symptoms from nearly 100% to about 50%.
“This is the first time we’ve seen that we can delay Alzheimer’s symptoms in people who were guaranteed to develop the disease,” said Dr. Randall J. Bateman, the study’s senior author. “While we don’t know yet how long the delay will last, this gives hope for longer, healthier lives.”
The drug used in the trial, gantenerumab, was designed to clear amyloid plaques from the brain. These plaques are believed to be the first step in the development of Alzheimer’s disease. Although gantenerumab is no longer in development, other drugs with similar effects are now being studied.
The participants had previously enrolled in the DIAN-TU-001 trial, the first global effort to prevent Alzheimer’s in people with these inherited mutations.
While early results showed that gantenerumab reduced amyloid levels, there was no obvious improvement in thinking ability because most participants hadn’t declined yet. To better understand its effects, researchers launched an extension of the trial where all participants received the drug.
The study showed that those who received the drug the longest were the most protected. Those who began taking gantenerumab during the extension phase—only for about two to three years—did not show significant improvements yet. This suggests that early and long-term treatment may be needed to prevent Alzheimer’s symptoms.
While the results are promising, the drug did come with side effects. About 30% of participants developed amyloid-related imaging abnormalities (ARIA), which can include brain swelling or small brain bleeds. Most cases were mild and temporary, though two people had to stop treatment. There were no deaths or life-threatening side effects.
Because gantenerumab is no longer being developed, most participants in the study have now switched to lecanemab, another FDA-approved anti-amyloid drug. A new phase of the trial—the Knight Family DIAN-TU Amyloid Removal Trial—is now underway to continue this important research.
Although the trial focused on people with early-onset, inherited Alzheimer’s, researchers believe the results could apply to the more common, late-onset form of the disease. Both forms begin with amyloid buildup decades before memory loss begins.
Dr. Bateman said he is optimistic that this research could eventually lead to treatments that prevent Alzheimer’s for millions of people. “We are moving closer to being able to prevent Alzheimer’s disease before it ever starts,” he said.
The Alzheimer’s Association is helping fund this work and has praised the results as groundbreaking. A new prevention trial is also underway to test another drug, remternetug, in even younger participants—some as young as 18—who may be up to 25 years away from showing symptoms.
These trials could be the key to stopping Alzheimer’s before it begins.
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