Association of Serum Magnesium Levels With Risk of Intracranial Aneurysm: A Mendelian Randomization Study | Neurology : Objective Magnesium has been implicated in regulating blood pressure and vascular endothelial cell function, but its role in the pathophysiology of intracranial aneurysm is not known. Here we performed a Mendelian randomization analysis to investigate the association between serum magnesium concentration and risk of intracranial aneurysm. Methods Five single-nucleotide polymorphisms strongly associated with serum magnesium concentrations in a genome-wide association study in 23 829 individuals of European ancestry were used as genetic instruments. Genetic association estimates for intracranial aneurysm were obtained from a genome-wide association study in 79 429 individuals (7495 cases and 71 934 controls). The inverse-variance weighted method was used in the primary analyses to obtain the causal estimates. Results Higher genetically predicted serum magnesium con...