Effects of physical exercise on cognitively impaired older adults: a meta-analysis of randomized control trials

Abstract Objectives: The main aim of this meta-analysis was to compare the effects of different physical activities on cognitive functions in older adults divided according to cognitive impairment levels. Methods: We searched Web of Science, Scopus, and PubMed for randomized control trials (RCT). A standardized mean difference (SMD) of the pre-post intervention score of global cognitive function tests were calculated by the random model in the Cochrane meta-analyses for people with cognitive impairment generally and across three levels - mild, mild to moderate, and moderate to severe cognitive impairment separately. Additionally, an unstandardized coefficient beta (B) was calculated in generalized linear models to estimate the effects of exercise, cognitive impairment severity, age, female ratio, length of intervention, and time of exercise a week on the global cognitive function. Results: Data from 26 studies involving 1,137 participants from intervention groups and 1,187 participants from control groups were analyzed. Physical exercise had a positive effect on cognitive functions in people across all levels of cognitive impairments SMD (95 % confidence interval [CI]) = 1.19 (0.77 - 1.62); however, heterogeneity was considerably high I 2 = 95%. Aerobic (B = 8.881) and resistance exercise (B = 4.464) was significantly associated with better results in global cognitive functions when compared to active control. A higher number of female participants cin intervention groups had a statistically significant effect on the global cognitive function (B = 0.229). onclusions: Physical exercise was associated with cognitive function improvement in older people with cognitive impairments. Aerobic exercise was more strongly associated than resistance exercise to combat cognitive decline. Keywords: Physical activity, Dementia, Aging, Meta-analysis, Aerobic exercise, Cognitive function