Leisure exercise cuts dementia risk, but work-related activity may raise it, large analysis finds
A large meta-analysis of 74 studies with 4.23 million people found that high levels of physical activity reduce dementia risk over about 10 years (RR around 0.80 for all-cause dementia), with leisure-time activities driving most of this benefit (RR ~0.76). In contrast, occupational physical activity and, in some cases, active commuting were linked to higher dementia risk, likely reflecting confounding factors such as education, job stress, environmental exposures, and reverse causation. The findings imply that not all activity confers the same brain benefits; voluntary, socially and cognitively engaging recreation may offer the strongest protection.