The risk of having at least 1 psychiatric disorder by age 16 years is much higher than point estimates would suggest. Concurrent comorbidity and homotypic and heterotypic continuity are more marked in girls than in boys.

We review recent research on the prevalence, causes, and effects of diagnostic comorbidity among the most common groups of child and adolescent psychiatric disorders; anxiety disorders, depressive disorders, attention deficit hyperactivity disorders, oppositional defiant and conduct disorders, and substance abuse. A meta-analysis of representative general population studies provides estimates of the strength of associations between pairs of disorders with narrower confidence intervals than have previously been available. Current evidence convincingly eliminates methodological factors as a major cause of comorbidity. We review the implications of comorbidity for understanding the development of psychopathology and for nosology.

We review recent research on the prevalence, causes, and effects of diagnostic comorbidity among the most common groups of child and adolescent psychiatric disorders; anxiety disorders, depressive disorders, attention deficit hyperactivity disorders, oppositional defiant and conduct disorders, and substance abuse. A meta-analysis of representative general population studies provides estimates of the strength of associations between pairs of disorders with narrower confidence intervals than have previously been available. Current evidence convincingly eliminates methodological factors as a major cause of comorbidity. We review the implications of comorbidity for understanding the development of psychopathology and for nosology.

This DataWatch explores the roles of human service sectors (mental health, education, health, child welfare, and juvenile justice) in providing mental health services for children. The data are from the first wave of the Great Smoky Mountains Study of Youth, a population-based study of psychopathology and mental health service use among children. The results show somewhat higher rates of mental health service use than has been reported previously, while continuing to show a substantial amount of unmet need, even among children with both a psychiatric diagnosis and functional impairment. The findings point to a significant role for the education sector, suggesting that schools may function as the de facto mental health system for children and adolescents.

When concurrent assessment rather than retrospective recall is used, there is no evidence for an increased prevalence of child or adolescent depression over the past 30 years. Public perception of an 'epidemic' may arise from heightened awareness of a disorder that was long under-diagnosed by clinicians.