When the population was stratified based on APOE-ε4 carrier status, physical activity did not affect the risk of developing AD among APOE-ε4 carriers (HR 1.00 per SD increase, 95% CI 0.89–1.13), nor among non-carriers (HR 1.04 per SD increase, 95% CI 0.92–1.16) in fully adjusted models (model 2). This evidence concerns the gene APOE and Alzheimer disease.