Baumeister SE, Karch A, Bahls M, et al. - Researchers assessed if physical activity can protect against Alzheimer disease (AD) via a 2-sample Mendelian randomization analysis. They used summary data on genome-wide association studies regarding physical activity and AD. The sample consisted of 21,982 patients with AD and 41,944 controls who were cognitively normal. Eight single nucleotide polymorphisms (SNPs) known at p < 5 × 10⁻⁸ to be linked to average accelerations and 8 SNPs correlated at p < 5 × 10⁻⁷ linked with vigorous physical activity (fraction of accelerations > 425 milligravities) acted as instrumental variables. Genetic liability for fraction of accelerations >425 milligravities was irrelevant to the risk of AD. A causal link between physical activity and AD risk is not confirmed by the current research.