Abstract
BACKGROUND: The causal relationships between amyotrophic lateral sclerosis (ALS), Parkinson disease and different intensities of physical activity (PA) are still inconclusive. To evaluate the causal impact of PA on ALS and Parkinson disease (PD), this study integrates evidence from Mendelian randomization (MR) using a meta-analysis approach. METHODS: MR analyses on genetically predicted levels of PA (compose of self-reported moderate-to-vigorous physical activity [MVPA], self-reported vigorous physical activity [VPA], and strenuous sports or other exercises [SSOE]) regarding ALS and PD published up to July 27, 2024, were obtained from PubMed, Scopus, Web of Science, and Embase. De novo MR studies were analyzed utilizing publicly accessible datasets from genome-wide association studies and then meta-analyses were performed to pool the results. RESULTS: Meta-analyses of results of 12 de novo MR studies analyses and 2 published MR studies indicated that genetic predicted levels of MVPA (odds ratio [OR]: 1.22, 95% confidence interval [CI]: 1.08-1.38), VPA (OR: 1.32, 95% CI: 1.08-1.60), and SSOE (OR: 1.35, 95% CI: 1.07-1.70) were related to a raised risk of ALS, but not causally with PD. CONCLUSION: Our findings showed no causal relationships between MVPA, VPA, SSOE, and PD, while MVPA, VPA, and SSOE were associated with increased ALS risk, highlighting the need for targeted PA recommendations for disease management.