Independent and combined effects of cognitive and physical activity on incident MCI.

INTRODUCTION:The objective of this study was to examine the independent and combined influences of late-life cognitive activity (CA) and physical activity (PA) on the risk of incident mild cognitive impairment (MCI). METHODS:We used interval censored survival modeling to examine the risk of incident MCI (Clinical Dementia Rating [CDR] = 0.5) as a function of CA (high vs. low) and at least moderate intensity PA (any vs. none) among 864 cognitively normal (CDR = 0) older adults. RESULTS:During three annual follow-up waves, 72 participants developed MCI. Compared with low CA with no PA, significant reductions in risk for MCI were observed for high CA with any PA (hazards ratio (HR) = 0.20, 95% confidence interval (CI) 0.07-0.52) and low CA with any PA (HR = 0.52, 95% CI 0.29-0.93), but not for high CA without PA (HR = 0.94, 95% CI 0.45-1.95). DISCUSSION:These findings suggest that a combination of CA and PA may be most efficacious at reducing the risk for cognitive impairment.