Using brain-imaging techniques to study some of the same individuals in a previous study, the researchers reported brain changes in people at three levels of genetic risk, some of which appear decades before the onset of symptoms. They have suggested the importance of conducting prevention trials starting in late middle-age, and also suggested how brain-imaging techniques could be used to evaluate these treatments without having to study thousands of people or wait many years to see which people go on to develop symptoms.

"The current findings provide new information about the cognitive declines associated with normal aging and the extent to which they are accelerated by the major genetic risk factor for Alzheimer's disease," said Eric Reiman, M.D., Executive Director of the Banner Alzheimer's Institute, Director of the Arizona Alzheimer's Consortium, and one of the study authors.

"Perhaps more important, these findings add to the evidence that certain Alzheimer's treatments may be most effective if started not only before people develop symptoms, but even before they reach older ages."

"This study highlights the idea that Alzheimer's disease is a progressive disorder that likely begins well before clinical diagnosis," said Creighton Phelps, Ph.D., who directs the Alzheimer's Disease Research Center program for the National Institute on Aging. "Additional research is needed to identify those at high genetic risk and develop methods to delay disease progression."

Alzheimer's disease afflicts about 10 percent of people over age 65 and almost half over 85. With the skyrocketing number of people living to older ages, there is an urgent need to find demonstrably effective Alzheimer's prevention therapies. The researchers do not recommend using brain imaging or cognitive tests to predict a healthy person's risk for developing Alzheimer's later in life. But they are excited about the chance to use these techniques in cognitively normal carriers of the APOE e4 gene to evaluate promising Alzheimer's prevention therapies as quickly as possible.

mayo/