Aerobic activity may reverse mental decline

NEW YORK (Reuters Health) - Regular aerobic exercise can not only stave off the decline in brain function that often comes with age, it can also help turn back the clock on brain aging, two experts in the field report, based on a critical review of published studies.

Age-related deterioration in the all-important white and gray matter in the brain makes a number of high-level "executive function" tasks -- such as planning, scheduling, working memory and multi-tasking -- much more difficult, Drs. Arthur F. Kramer and Kirk I. Erickson explain in the latest issue of the British Journal of Sports Medicine.

Yet a substantial body of research shows that these are the very processes that are most responsive to physical exercise, note the authors from the University of Illinois Beckman Institute, Urbana.

In people with or those without signs of dementia or Alzheimer's disease, regular moderate physical activity, enough to make a person breathless, has been shown to boost not only the speed and sharpness of thought but also the actual volume of brain tissue and the way in which the brain functions, Kramer and Erickson note.

For example, in a 6-month study Kramer and colleagues conducted, adults ages 60 to 75 who walked briskly for 45 minutes a day three days a week not only improved their aerobic fitness but also their mental fitness -- particularly their ability to perform executive function tasks - compared with a control group who engaged only in non-aerobic stretching and toning exercises.

These results suggest that regular moderate aerobic exercise can "reliably reverse age-related cognitive decline," Kramer and Erickson write, and that the aging brain retains its capacity to grow and develop.

Other researchers, they note, have found that physically fitter adults have less evidence of deterioration in gray matter (critical to thinking) than their less physically fit counterparts.

Still others have found that physically fitter older women going through menopause -- a time of declining estrogen levels and memory trouble -- have more gray brain matter and perform better on measures of executive control than their less physically fit peers, whether or not they are taking hormone replacement therapy, which can boost cognitive function.

Summing up, Kramer and Erickson point out that "many questions remain unanswered" regarding the effects of exercise on the brain. However, "we can safely argue that an active lifestyle with moderate amounts of aerobic activity will likely improve cognitive and brain function, and reverse the neural decay frequently observed in older adults," they conclude.

SOURCE: British Journal of Sports Medicine 2008.