Causal association between brain structure and obstructive sleep apnea: A mendelian randomization study

Objective: Previous studies have reported contradictory findings regarding the relationship between obstructive sleep apnea (OSA) and abnormal brain morphology. Furthermore, the causal relationship between OSA and brain morphology has not been clearly established. The aim of this study was to utilize Mendelian randomization (MR) analysis to investigate the impact of obstructive sleep apnea (OSA) on brain morphology and determine its potential causal relationship. Methods: Firstly, the inverse-variance weighted (IVW) method was employed to assess the causal effects of OSA on cortical surface area and brain structure volume. Additionally, two additional MR methods, namely weighted median and MR-Egger, were used to supplement the results from IVW. Subsequently, a reverse MR analysis was conducted to determine the direction of causality. Furthermore, sensitivity analyses were performed including Cochrane's Q test, MR-Egger intercept test, MR-PRESSO global test, and leave-one-out analysis. Results: The results of the study showed that OSA patients had a tendency towards decreased cortical surface area and hippocampal volume in the precuneus region compared to individuals without OSA, while the superior temporal cortical surface area showed an increase. The results from the weighted median and MR-Egger analyses were consistent with those from the IVW analysis. Sensitivity tests confirmed the reliability of the causal estimates. Conclusions: This study provides preliminary evidence of an association between OSA and brain structure using large-scale genome-wide association data. The results demonstrate that OSA is associated with changes in brain structure. Therefore, individuals with OSA should be vigilant about the risks of related diseases due to alterations in brain tissue.