Beta-Amyloid May Identify Alzheimer’s Disease
Studies Suggest Potential Approach for Identify People at Risk for Alzheimer’s
FDA Advisory Panel continued...
But preliminary materials released by FDA today raised doubts about the drug’s chances for approval.
In a briefing posted on the FDA’s web site in preparation for the meeting, at least one reviewer concluded that data from the study failed to provide convincing evidence to support the drug’s usefulness. The reviewer cited “significant limitations” in the study’s design, size, and execution that “cast doubt on the ... validity, reproducibility, and clinical utility” of the imaging procedure.”
A spokesperson for Eli Lilly declined to comment on the briefing Tuesday, telling WebMD the company was “looking forward” to making its case for the drug at Thursday’s meeting.
Beta-Amyloid in the Blood
In the second study, researchers reported that low levels of beta-amyloid in the blood predicted cognitive decline over a nine-year period.
The study included close to 1,000 older adults enrolled in a larger health study with no evidence of dementia at enrollment.
Beta-amyloid levels were measured soon after enrollment and the participants were followed for close to a decade.
Low levels of amyloid 42/40 at enrollment were found to be associated with greater cognitive decline, especially among less educated people and those with lower reading skills.
This finding bolsters the hypothesis that people with greater cognitive reserves, as measured by higher education and higher literacy, may be less likely to develop dementia than those with fewer reserves when beta-amyloid is present in the brain.
“Cognitive reserve is a broad concept used to explain why some individuals have measurable pathological burden of beta-amyloid (at autopsy) but do not experience clinical symptoms of cognitive decline,” they write.
Alzheimer’s researcher Monique Breteler, MD, PhD, tells WebMD that both the blood and imaging approaches show promise, but she says their usefulness at present may be limited to research.
Breteler is a professor of epidemiology at Erasmus University in the Netherlands.
“We don’t have good treatments for Alzheimer’s disease, and all the evidence suggests that when we find these treatments they will be most effective early in the course of disease,” she says.
In an editorial also published in The Journal of the American Medical Association, Breteler concluded that more rigorously designed studies are needed to confirm the clinical usefulness of the techniques.
“The stakes involved in finding good biomarkers for Alzheimer’s disease and other neurodegenerative diseases are high indeed -- too high to be able to afford jumping to unwarranted conclusions and heading in the wrong direction,” she writes.