Psychiatric comorbidity in children and adolescents with ADHD: A systematic review and meta-analysis.

Attention Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder with estimated worldwide prevalence of 7.2 % in children and adolescents. Comorbidity of psychiatric disorders is considered common in ADHD and has been found to contribute to poorer prognosis. Despite decades of research, the actual prevalence of comorbid psychiatric disorders in children and adolescents with ADHD is unclear. The purpose of this systematic review and meta-analysis was to investigate the prevalence of comorbid disorders in children and adolescents with ADHD. Embase OVID, Ovid MEDLINE and PsycINFO were systematically searched for eligible studies published up to February 2025. In total 121 studies involving 39,894 children and adolescents with ADHD diagnosis were included. The most common comorbid disorders were Oppositional Defiant Disorder (34.7 %), Behavior Disorders (30.7 %), Anxiety Disorders (18.4 %), Specific phobias (11.0 %), Enuresis (10.8 %), and Conduct Disorder (CD) (10.7 %). All individual disorders studied had a higher prevalence among children and adolescents with ADHD than in the general population. Few gender differences were found; higher prevalence of CD among boys and higher of OCD in girls. The findings indicate that comorbid psychiatric disorders are highly prevalent in children and adolescents with ADHD and must be considered in both assessment and treatment of ADHD. PROSPERO registration: ID CRD42022359965.