Early results from a multisite prevention study—the Anti-Amyloid Treatment in Asymptomatic Alzheimer disease (A4) study—suggests that abnormal levels of amyloid-beta protein, detectable by PET scans, in the brains of asymptomatic older people may be early indications of Alzheimer’s disease.
The early findings suggest that about 30 percent of 4,486 people who had no signs of cognitive impairment at baseline—after an extensive battery of neurocognitive assessments— tested positive for Abeta on the PET scan. At the screening, everyone underwent blood tests to look for the most common AD risk gene, APOE4. The researchers found that amyloid-positive individuals performed slightly worse on the neurocognitive tests compared with those who did not have evidence of Abeta accumulating in their brains.
What’s more, people who said they felt that their cognitive abilities were slipping—evidenced on a 15-item questionnaire—were more likely to also have higher Abeta levels, as were those with at least one APOE4 allele.
“This is clear evidence that we can identify people in the preclinical stages of Alzheimer’s who have elevated beta-amyloid in their brains,” said Reisa A. Sperling, MD, a professor of neurology at Harvard Medical School and director of the Center for Alzheimer Research and Treatment at Brigham and Women’s Hospital.