Depression and multiple sclerosis: A bidirectional Mendelian randomisation study

Depression is common in multiple sclerosis (MS); however, the underlying mechanism for the relationship remains unknown. In this study, we examined a putative causal relationship between depression and MS using a bidirectional Mendelian randomisation (MR) framework. Using the latest genome-wide association study data available, 168 non–major histocompatibility complex (MHC) independent variants associated with MS and 96 independent genetic variants associated with depression susceptibility were used. Maximum likelihood, weighted median, inverse variance weighted method and MR-Egger regression analyses were performed. There was no significant risk for the development of MS in persons carrying variants associated with depression or for risk of depression in individuals who are genetically susceptible to MS.