Leisure time physical activity and dementia risk: a dose-response meta-analysis of prospective studies

Background There is considerable evidence of the favourable role of more physical activity (PA) in fighting against dementia. However, the shape of the dose-response relationship is still unclear. Objective To quantitatively investigate the relationship between dementia and PA. Design PubMed, EMBASE, Ovid and the Cochrane Library were searched for prospective studies published from 1 January 1995 to 15 October 2016. Two types of meta-analyses were performed with a focus on the dose-response relationship using two stage generalised least squares regression. Results The primary analysis exhibited a dose-response trend for all-cause dementia (ACD), Alzheimer's disease (AD) but not for vascular dementia (VD). In the dose-response analysis, either ACD (p(trend) <0.005; p(non-linearity)=0.87) or AD (p(trend) <0.005; p(non-linearity)=0.10) exhibited a linear relationship with leisure time PA (LTPA) over the observed range (0-2000 kcal/week or 0-45 metabolic equivalent of task hours per week (MET-h/week)). Specifically, for every 500 kcal or 10 MET-h increase per week, there was, on average, 10% and 13% decrease in the risk of ACD and AD, respectively. Conclusions We have reported, for the first time, the dose-response relationship between LTPA and dementia, further supporting the international PA guideline from the standpoint of dementia prevention.