Effects of physical activity and exercise interventions on Alzheimer's disease: an umbrella review of existing meta-analyses

Introduction During the last decade, physical activity (PA) (or "exercise") has been identified as one of the main modifiable factors that influence the development of Alzheimer's disease (AD) pathophysiology. We performed an umbrella review to summarize the evidence on the association between PA/exercise and the risk of developing AD risk, and the effect of exercise interventions on the progression of AD. Methods A systematic search was performed in PubMed, SportDiscus, Cochrane Library and Web of Science (March 2022) to identify meta-analyses assessing the association between PA and the incidence of AD, and assessing the effect of exercise interventions on patients with AD. Results Twenty-one studies were included. The results with strongest evidence revealed the positive effects of PA on AD risk. Specifically, meeting the WHO recommendations for PA was associated with a lower risk of AD. They also revealed positive effects of exercise on cognitive function, physical performance, and functional independence. Conclusions There is strong evidence of a protective effect of regular PA against AD risk; however, the dose-response association remains unclear. Physical exercise seems to improve several dimensions in patients with AD, although research is warranted to elucidate the exercise characteristics that promote the greatest benefits.