Additional sensitivity analyses were performed. First, we repeated the analyses for specific mental disorders, pre-selected on the basis of their epidemiological and clinical relevance: attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), generalised anxiety disorder (GAD), panic disorder, separation anxiety disorder, specific phobia, social anxiety disorder, obsessive-compulsive disorder (OCD), disorders due to use of alcohol, disorders due to use of cannabis, anorexia nervosa, bulimia nervosa, binge eating disorder, depressive disorders, bipolar or related disorders (bipolar disorder), acute and transient psychotic disorders (ATPD), schizophrenia, and post-traumatic stress disorder (PTSD). Second, we repeated analyses for any disorder, stratifying by onset definition (i.e., first symptoms, first diagnosis, first hospitalisation). Third, we repeated the analyses for any disorder stratifying by sex. Finally, we compared the median age at onset between each pair of specific mental disorders, counting the proportion of bootstrapped randomisations in which the median age at onset of one disorder was larger than the median age of the other disorder (alpha = 0.05, two-sided).
