Exercise can help avoid memory problems as we age, and some of these benefits may be even greater for women, the journal Neurology writes. The study examined cognitive reserve, or the brain's ability to withstand the effects of diseases such as Alzheimer's disease without reducing thinking or memory. Women had higher cognitive reserve if they exercised regularly, took classes, read or played games. Participation in more vigorous mental activity, on the other hand, increased thinking speed in both women and men. There were 758 participants in the study (average age 76). Some participants showed no signs of thinking or memory problems, others had mild cognitive impairment, and some had full-blown dementia at the start of the study. Participants underwent brain scans and tests for thinking speed and memory. The researchers compared the results of these tests with brain changes associated with dementia to calculate a measure of cognitive reserve. Women who reported more physical activity had greater reserve for thinking speed, but this was not observed in men. Greater physical activity was not associated with improved memory reserve in either men or women. Women who read, took classes, and played cards or games more often also showed higher memory reserve.