In Brief: Disease-modifying drug fails in Alzheimer's study

Alzheimer's disease currently affects roughly five million Americans and is the sixth leading cause of death in the United States. Statistics provide only one way to measure the toll: Alzheimer's progressively robs people of memory, personality, and independence.

The leading hypothesis about how the disease develops is that sticky deposits of beta-amyloid protein accumulate in the brain, causing physiological changes that kill neurons and other brain tissue. Yet the slow pace of the disease — with symptoms usually developing decades after beta-amyloid deposits start forming — had raised hopes that it might be possible to find ways to intervene early and slow or even stop the process.