The causal relationship between six mental disorders and breast cancer risk: A two-sample Mendelian randomization study

Psychological disorders such as schizophrenia, bipolar disorder (BD), major depressive disorder (MDD), attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and anxiety disorder (AD) are widespread. Mendelian randomization (MR) was used in this study in order to investigate possible causal relationships between psychiatric disorders and breast cancer (BC). We employed publicly accessible summary statistics from extensive genome-wide association studies to identify, perform quality control, and cluster genetic variant loci linked to schizophrenia, ADHD, MDD, ASD, BD, AD, and BC as instrumental variables. The MR analysis utilized inverse variance weighting, MR-Egger regression, and weighted median estimation to assess the causal links between psychiatric disorders and BC. Additionally, heterogeneity and sensitivity tests were conducted to ensure the robustness of inverse variance weighting results. According to the results of the two-sample MR analysis, schizophrenia, BD, MDD, ADHD, ASD are not causally linked to BC. According to the results of the two-sample MR analysis, schizophrenia, BD, MDD, ADHD, ASD are not causally linked to BC. But there is a causal relationship between AD and BC. The MR analysis showed no evidence of a causal relationship between schizophrenia, BD, MDD, ADHD, ASD, and BC risk. However, research found a genetic causal relationship between AD and BC, and it is positively correlated.