Exploring the causal relationship between BMI and psychiatric disorders using two-sample Mendelian randomization

Abstract

Background The study aimed to assess the causal relationship using two-sample Mendelian randomization analyses of BMI and five classic psychiatric disorders (depression, bipolar disorder, schizophrenia, autism, and anxiety disorder) in sequence. Methods Data related to BMI, depression, bipolar disorder, schizophrenia, autism, and anxiety disorders were downloaded from the GWAS database, and based on the genetic variation associated with each data were analyzed by utilizing five methods: MR Egger, Weighted median, Inverse variance weighted, Simple mode, Weighted mode, and five methods, while Mendelian randomization analysis between two samples was performed. Results Under IVW analysis, a positive causal relationship was found between BMI and depression (OR: 1.009, 95% CI: 1.002–1.016, P = 0.009) as well as bipolar disorder (OR: 1.001, 95% CI: 1.001–1.002, P = 0.002). Additionally, a negative causal relationship was found between BMI and schizophrenia (OR: 0.702, 95% CI: 0.560–0.881, P = 0.002). However, no causal relationship was found between BMI and autism (OR: 1.114, 95% CI: 0.972–1.278, P = 0.120) or anxiety disorders (OR: 1.000, 95% CI: 0.998–1.001, P = 0.630). Conclusion A causal relationship between BMI in depression, bipolar disorder, and schizophrenia. Maintaining BMI within the range of normal indicators is important not only for physical health care, but also for the prevention of psychiatric disorders.