Detecting Alzheimer's disease before it's too late

Determining how early to intervene is a central challenge in slowing the progression of AD. Clinical trials of drugs for lowering amyloid levels typically involve individuals who do not yet have symptoms but are considered "amyloid positive" and at risk for developing AD. These trials have been largely unsuccessful, perhaps because they begin too late.

To untangle the relationship between beta-amyloid, the AD-associated protein tau, and memory impairment over time, Stephanie Leal, William Jagust and colleagues studied healthy men and women between the ages of 61 and 88 over a five-year period. Brain scans revealed that even trace amounts of beta-amyloid predicted future levels of tau, and both preceded memory decline. The researchers found that greater baseline levels of beta-amyloid were associated with a faster rate of accumulation, but only to a point, after which higher beta-amyloid levels were associated with slower accumulation.