Effect of physical activity on memory function in older adults with mild Alzheimer's disease and mild cognitive impairment

Aim: It is very important to maintain cognitive function in patients with mild cognitive disorder. The aim of the present study was to determine whether the amount of physical activity is associated with memory function in older adults with mild cognitive disorder. Methods: A total of 47 older adults with mild cognitive disorder were studied; 30 were diagnosed with mild Alzheimer's disease and 17 with mild cognitive impairment. The global cognitive function, memory function, physical performance and amount of physical activity were measured in these patients. We divided these patients according to their walking speed (<1m/s or >1m/s). A total of 26 elderly patients were classified as the slow walking group, whereas 21 were classified as the normal walking group. Results: The normal walking group was younger and had significantly better scores than the slow walking group in physical performance. Stepwise multiple linear regression analysis showed that only the daily step counts were associated with the Scenery Picture Memory Test in patients of the slow walking group (β=0.471, P=0.031), but not other variables. No variable was significantly associated with the Scenery Picture Memory Test in the normal walking group. Conclusions: Memory function was strongly associated with the amount of physical activity in patients with mild cognitive disorder who showed slow walking speed. The results show that lower physical activities could be a risk factor for cognitive decline, and that cognitive function in the elderly whose motor function and cognitive function are declining can be improved by increasing the amount of physical activity.