Mendelian randomization studies on cardiometabolic factors and intracranial aneurysms: A systematic literature analysis.

Objectives: Intracranial aneurysm (IA) has an insidious onset, and once ruptured, it carries high rates of mortality and disability. Cardiometabolic factors may be associated with the formation and rupture of IA. This study aims to summarize the application of Mendelian randomization (MR) methods in research on cardiometabolic factors and IA, providing insights for further elucidation of IA etiology and pathogenesis.

Methods: Literature about MR-based IA studies published up to February 21, 2024, was retrieved from PubMed, Embase, Web of Science, CNKI, and Wanfang. Two researchers independently performed literature screening, data extraction, and quality assessment. A narrative synthesis approach was used to conduct a qualitative systematic review of the included studies.

Results: A total of 11 MR-based studies on IA published between 2017 to 2024 were included, of which 4 were rated as high quality. These studies investigated the associations between blood pressure, blood lipids, blood glucose, obesity-related indicators, and inflammatory cytokines with IA and its subtypes, though issues of duplication were noted. Four MR studies based on the same European population but using different instrumental variable selection criteria, as well as another MR study in a different European cohort, consistently identified blood pressure as a risk factor for IA and its subtypes. Findings for blood lipids, blood glucose, obesity-related indicators, and inflammatory cytokines were inconsistent across MR studies.

Conclusions: Blood pressure appears to increase the risk of IA and its subtypes. Associations between other cardiometabolic factors and IA/subtypes require further in-depth investigation. Given the inherent limitations of MR studies, causal inferences should be made cautiously in combination with other lines of evidence.