Genetic evidence strengthens the bidirectional connection between oral health status and psychiatric disorders: A two-sample Mendelian randomization study

Observational studies cannot accurately infer the causal associations between oral health status and psychiatric disorders. We conducted univariate and multivariate Mendelian randomization (MR) analyses using single nucleotide polymorphisms (SNPs) associated with eight oral health statuses (periodontitis, DMFS, Nteeth, toothache, loose teeth, painful gums, bleeding gums, and mouth ulcers) and four psychiatric disorders (Schizophrenia, Major Depressive Disorder (MDD), anxiety and stress-related disorder (ASRD), and Bipolar Disorder (BIP)) as instrumental variables. Genetic data were sourced from the Gene-lifestyle interactions in dental endpoints (GLIDE), UK Biobank, Psychiatric Genomics Consortium (PGC), and Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSYCH). The inverse variance-weighted (IVW) approach, supported by a comprehensive sensitivity analysis, was employed. Genetically predicted mouth ulcers were significantly linked to higher MDD (OR = 2.17, 95 % CI: 1.33‐–3.54, P