were primarily reported in paediatric studies (only 1 study on adults reported ASD, while none reported ODD). The prevalence of personality disorders, from studies on adults, was also found to be high [35% (95% CI 28–42%)]. Among personality disorders, the most commonly reported was obsessive-compulsive personality disorder (OCPD) [17% (95% CI 12–22%)]. A very high level of heterogeneity (I2 > 90%) was found for nearly all the comorbidities examined.
