Among children and adolescents, mental disorders account for the most years lived with disability; however, evidence on the incidence of the full spectrum of mental disorders during this developmental period is lacking. The current population-based cohort study examined incidence and risk of 27 specific categories of mental disorders before the age of 18 years among people living in Denmark from 1995 to 2016 (1.3 million; 14.4 million person-years of follow-up). Registers including nationwide data were used to collect age, sex and diagnoses of mental disorders. The study found that the risk of being diagnosed with any mental disorder before the age of 18 years of age was 15.05% (14.63% in girls and 15.51% in boys), which is consistent with United States and estimated worldwide prevalence rates. In girls, the category with the highest cumulative incidence was anxiety disorders (7.85%); in boys, attention-deficit/hyperactivity disorder (ADHD) had the highest cumulative incidence (5.90%). Incidence for schizophrenia spectrum disorders peaked in late adolescence (approximately 17-18 years of age), with girls showing higher cumulative incidence than boys by age 18 years; similar patterns were observed for mood, anxiety, obsessive-compulsive, eating and personality disorders (Figure 1). Conversely, by age 18, boys had higher risks of intellectual disability, autism spectrum disorder (ASD), other developmental disorders, ADHD, oppositional defiant disorder/conduct disorder (ODD/CD), attachment disorder and tic disorders than girls (Figure 1). Notably, the incidence of ASD, ADHD, ODD/CD, other developmental disorders and attachment disorder peaked later in girls (adolescence) than boys (childhood). Indeed, cumulative incidence of any mental disorder before age 6 and 13 years of age was higher in boys (2.78% and 10.23%, respectively) than girls (1.45% and 5.17%, respectively), suggesting delayed detection of mental disorders in girls. Notably, sex differences in the risk of organic mental disorders, substance use disorders (including alcohol abuse and cannabis use) and bipolar disorder were not found. These robust and comprehensive findings are broadly representative of many high-income nations and demonstrate the need to strengthen advocacy and policies for child and adolescent mental health services.
Figure. Cumulative incidence of mental disorders by age 18 years stratified by disorders with a significantly greater incidence in boys versus girls (left panel) and girls versus boys (right panel).
Dalsgaard S et al. JAMA Psychiatry 2020;77(2):155-64. Abstract
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