Abdominal obesity mediates the causal relationship between depression and the risk of gallstone disease: retrospective cohort study and Mendelian randomization analyses

•Depression is associated with a higher risk of gallstone disease.•Mendelian randomization is a valuable approach for causal inference.•Major depression may causally predict the incidence of gallstone disease.•Abdominal obesity mediates the causal effect of depression on gallstone disease.•The causal relationship needs to be further verified in East-Asian populations.