Two new studies report that engaging in moderate to vigorous physical activity may not only stave off the cognitive decline that is often a precursor to dementia, but it may also reverse it. The studies are both published in the in journal Archives of Neurology.

In the first study, over 1,300 participants who were free of dementia at the study’s outset answered questions about their activity levels during their middle−age and senior years. The individuals who said they engaged in moderate exercise during middle−age had a 39% reduced risk of suffering from mild cognitive decline. Those who were active into their silver years were at a 32% reduced risk of cognitive deficits. The researchers suggest that the protective effects of exercise observed in the study come from a number of factors, including better circulation to the brain and increased brain cell production and survival.

After six months of engaging in their respective activities, those in the aerobic exercise group had better cognitive function than those in the control group.

The study was led by Yonas E. Geda, a researcher at the Mayo Clinic.

The second study looked at older individuals who were already suffering from mild cognitive decline. The researchers, led by Laura D. Baker, divided the participants into two groups. The first group engaged vigorous (aerobic) activity for 45−60 minutes per day, while the other, serving as controls, did stretches instead.

After six months of engaging in their respective activities, those in the aerobic exercise group had better cognitive function than those in the control group. The result was particularly pronounced in women, as compared to men, which the researchers say probably has to do with how the sexes differ in the ways their bodies make and metabolize insulin, glucose, and cortisol (a stress hormone).

The authors say that “[a]erobic exercise is a cost−effective practice that is associated with numerous physical benefits. The results of this study suggest that exercise also provides a cognitive benefit for some adults with mild cognitive impairment.” The importance of exercise to body and mind was also the subject of a number of studies reported in The Archives of Internal Medicine.

Baker and her team are researchers at the University of Washington School of Medicine and Veterans Affairs Puget Sound Health Care System in Seattle.