If you’re concerned about getting Alzheimer’s disease, don’t just sit there—do something!

And that something is exercise. Exercise can reduce amyloid plaques, the hallmark of Alzheimer’s, in the brains of cognitively normal individuals, including individuals who carry the APOE-e4 gene variant. The e4 variant is a well-established risk factor for Alzheimer’s.

So suggests a study in the January 9 Archives of Neurology. The lead investigator was Denise Head, Ph.D., an associate professor of psychology at Washington University, and the senior investigator was David Holtzman, M.D., chair of neurology there.

A total of 163 cognitively normal adults aged 45 to 88 were recruited for the study. Their brains were scanned for amyloid plaques. They filled out a validated questionnaire to estimate how much they had walked, jogged, or run during the prior decade.

Thirty-eight subjects were found to have engaged in exercise at or above the levels recommended by the American Heart Association; the remaining 125 were not. The subjects were also genotyped to see whether they had an e4 variant of the APOE gene. Fifty-two did; the remaining 111 did not. The researchers then looked to see whether there were links between levels of brain amyloid plaques, levels of exercise, and APOE-e4 status, while taking possible confounders such as age, gender, education, or high blood pressure into consideration.

They found that such links did exist. APOE-e4 carriers had significantly higher levels of amyloid plaques in their brains than noncarriers did. Subjects who exercised at or above the levels recommended by the American Heart Association had significantly lower levels of amyloid plaques in their brains than did subjects who exercised less. And e4 carriers who exercised at or above the levels recommended by the American Heart Association had significantly lower levels of amyloid plaques in their brains than did e4 carriers who exercised less.

Putting these findings together, it suggests that exercise might help ward off Alzheimer’s in all of us, including those individuals who are at higher risk of the disease because they possess an e4 variant of the APOE gene.

Head and her colleagues now want to conduct a longitudinal study to see whether that might be the case, she told Psychiatric News.

The study was funded by the National Institutes of Health.

An abstract of “Exercise Engagement as a Moderator of the Effects of APOE Genotype on Amyloid Deposition” is posted at http://archneur.ama-assn.org/cgi/content/abstract/archneurol.2011.845.