Causal relationship between psychiatric traits and temporomandibular disorders: a bidirectional two-sample Mendelian randomization study

Objectives This study was to investigate the causal relationship between temporomandibular disorders (TMD) and psychiatric disorders by Mendelian randomization (MR) analysis.Materials and methods A two-sample bidirectional MR analysis was adopted to systematically explore the causal relationship between TMD and eight psychiatric traits, including anxiety disorder (AD), panic disorder (PD), major depressive disorder (MDD), neuroticism, attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), bipolar disorder (BIP), and schizophrenia (SCZ). Inverse variance weighted (IVW), weighted median, and MR-Egger regression were used in my study. Furthermore, we also performed three sensitivity analyses to illustrate the reliability of the analysis.Results Two psychiatric traits have risk effects on TMD: PD (OR = 1.118, 95% CI: 1.047-1.194, P = 8.161 x 10(-4), MDD (OR = 1.961, 95% CI: 1.450-2.653, P = 1.230 x 10(-5)). Despite not surpassing the strict Bonferroni correction applied (P > 0.00625), we could think that there was a suggestive causal effect of neuroticism and SCZ increasing the risk of TMD. On the reverse MR analysis, we found no significant evidence of causal effects of TMD on these psychiatric traits. Except for heterogeneity in the causal analysis for SCZ on TMD, no heterogeneity and horizontal pleiotropy were detected in the other analyses.Conclusions Our two-sample MR study has provided further evidence of PD and MDD being related to a higher risk of TMD.Clinical relevance These findings highlight the importance of closely monitoring mental traits during future TMD treatments to prevent an increased risk of TMD.