Physical activity promotes changes in the brain that may protect high-risk individuals against cognitive decline, including development of Alzheimer's disease, according to a new study done at the University of Wisconsin-Milwaukee (UWM).

J. Carson Smith, an assistant professor of health sciences, included in the study both people who carry a high-risk gene for Alzheimer's disease, and other healthy older adults without the gene.

The study will be published in Vol. 54 (January 2011) of the journal NeuroImage.

Smith said: "Our study suggests that if you are at genetic risk for Alzheimer's disease, the benefits of exercise to your brain function might be even greater than for those who do not have that genetic risk.

A team of researchers compared brain activation during memory processing in four separate groups of healthy 65- to 85-years-olds.

Functional magnetic resonance imaging (fMRI) was used to measure brain activation of participants while they performed a mental task involving discriminating among famous people.

In the study groups of those carrying the gene, individuals who exercised showed greater brain activity in memory-related regions than those who were sedentary.

Furthermore, physically active people with the gene had greater brain activity than those who were physically active but not gene carriers.