A further systematic review has been published on the likely beneficial effects of physical activity in the prevention or long-term avoidance of cognitive decline and dementia.
Blondell, SJ. Hammersley-Mather, R. Veerman, JL. (2014). Does physical activity prevent cognitive decline and dementia?: a systematic review and meta-analysis of longitudinal studies. BMC Public Health. May 27th 2014; 14(1): 510. [Epub ahead of print].