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

Background: Considerable evidences were indicative of favorable roles of physical activity (PA) in fighting against dementia. However, the shape of dose–response relationship has not been explored. Objective: To conduct a meta-analysis to quantitatively investigate the relationship of dementia with PA by metabolic equivalent of task (MET)-hour/week and kilocalorie (kcal)/week. Design: Prospective studies published from Jan 1, 1995 to August 2016 were searched in PubMed, EMBASE, Ovid and the Cochrane Library. Two meta-analyses were performed with the focus on exploring the dose-response relationship using two-stage generalized least squares regression. Results: The qualitative analysis showed a trend of dose-response relationship with all-cause of dementia (ACD), Alzheimer’s disease (AD) but not vascular dementia (VD). In the dose-response analysis, ACD (p-trend<0.005; p-nonlinearity=0.87) and AD (p-trend<0.005; p-nonlinearity= 0.10) exhibited a linear relationship with leisure-time PA (LTPA) over the observed range (0-2000 kcal/week or 0–45 MET-h/week). Specifically, for every 500 kcal or 10 MET-h increase per week, the decrement of risk is roughly 10% (95%CI, 0.85-0.97) for ACD and 13% (95%CI, 0.79-0.96) for AD. Conclusions: We for the first time proved the dose-response relationship between LTPA and dementia/AD, which finding further supported the international PA guideline from a standpoint of dementia prevention.