Understanding the relationship between loneliness, substance use traits and psychiatric disorders: a genetically informed approach

•Genomic Structural Equation Modelling was used to implement factor analysis on 11 psychiatric traits.•The 11 psychiatric traits clustered into three latent genetic factors encompassing neurodevelopmental/mood conditions, substance use traits and disorders with psychotic features.•Loneliness was uniquely genetically associated with the latent factor representing neurodevelopmental/mood conditions.•Mendelian randomization provided evidence suggesting a bidirectional causal effect between loneliness and neurodevelopmental/mood conditions.