Effects of Obstructive Sleep Apnea on Personality and Temperament: A Cohort and Mendelian Randomization Study
ABSTRACT Objective Obstructive sleep apnea (OSA) is associated with neurocognitive impairment, but its causal relationship with personality traits remains poorly understood. This study investigates the association and causality between OSA and personality using both cohort and genetic data. Method This study included adults undergoing full‐night polysomnography (PSG). Personality traits were assessed using the Eysenck Personality Questionnaire (EPQ), which assesses extraversion, neuroticism, psychoticism, and lie scales. Based on Eysenck's theory, participants were classified into melancholic, choleric, phlegmatic, and sanguine temperaments. Bidirectional Mendelian randomization (MR) analysis was conducted using GWAS data from the FinnGen database to infer causality. The inverse‐variance weighted (IVW) method was used as the primary analysis. Sensitivity, pleiotropy, and heterogeneity analyses were conducted to validate the results. Results A total of 233 participants were included. OSA was associated with significantly reduced neuroticism (p = 0.020) and psychoticism (p = 0.047). No significant differences were found in extraversion or lie scores. MR analysis indicated a modest causal effect of OSA on reduced neuroticism (p = 0.023–0.030), while cohort data showed temperament shifts from melancholic to choleric/sanguine types with OSA severity (p < 0.001). Conclusions OSA may contribute to reduced neuroticism and altered temperament, highlighting the need for psychological screening in OSA management. Caution is warranted in interpreting causality due to modest MR effect sizes and potential heterogeneity.