These findings provide the first lifetime prevalence data on a broad range of mental disorders in a nationally representative sample of U.S. adolescents. The prevalence rates reported here closely approximate those of our nationally representative sample of adults using nearly identical methods, suggesting that the majority of mental disorders in adults emerge prior to adulthood. These rates are somewhat higher than those of prior studies, but within the ranges of estimates summarized in a meta-analysis of international community surveys of mental disorders in youth.1
In addition, the NCS-A provides a more comprehensive assessment of a wide range of DSM-IV disorders and subtypes than most previous studies. Despite the high prevalence rates, however, only about one in every four-to-five youths meet criteria for a lifetime mental disorder that is associated with severe role impairment and/or distress. The prevalence of severe emotional and behavior disorders is even higher than the most frequent major physical conditions in adolescence, including asthma24
which have received widespread public health attention.
The finding that only about half of youth with a lifetime DSM-IV disorder report severe impairment confirms previous research demonstrating that a smaller proportion of youth with mental disorders actually have sufficiently severe distress or impairment to warrant immediate intervention.9
According to prior research, about one out of every ten youths with a current mental disorder fulfill criteria for Serious Emotional Disorder (SED) based on the Substance Abuse and Mental Health Services Administration (SAMSHA) definition (e.g., a mental health problem that has a drastic impact on a child’s ability to function socially, academically, and emotionally). 9,26
While our study did not strictly assess all of the criteria for SED, our estimates of severe disorders were based on the full diagnostic criteria for DSM-IV disorders accompanied by severe impairment in major life roles.
Our data document the early onset of major classes of mental disorders. Among affected adolescents, 50% of disorders had their onset by age 6 for anxiety disorders, by age 11 for behavior disorders, by age 13 for mood disorders and by age 15 for substance use disorders. These findings closely approximate those of prospective studies of child and adolescent samples that have documented the incidence and progression of childhood mental disorders.2, 27–29
The early age of onset of anxiety has been well-established and our findings on specific subtypes of anxiety closely track those of prospective community-based research that reveal differential peak periods of onset of specific subtypes of anxiety. 29–31
Prospective studies have also shown that the average age of onset of major depression and dysthymia is between 11 and 14 years,6
with a steady increase in incidence across adolescence that continues through early adulthood. Our cross-sectional data reflect this increase with a near doubling of rates from 13–14 years (8.4%) to 17–18 years (15.4%). Also consistent with prior cross-sectional and prospective research, the median onset of behavior disorders is slightly earlier than that of mood disorders, with a later peak for conduct disorder than for oppositional defiant disorder. 32
Finally, the later onset and steeper increase in rates of substance use disorders across adolescence has been repeatedly demonstrated, despite different prevalence periods and assessment methods. 33
About 40% of affected youth in the NCS-A reported more than one class of lifetime disorder, with mood disorders being the most likely to co-occur with other classes. Non-random patterns of comorbidity between discrete classes of mental disorders have been documented extensively in prior community samples of youth.34–36
Future analyses of these data will investigate specific concurrent and prospective comorbidity patterns as well as their sociodemographic and clinical correlates.
In addition to providing prevalence estimates, the findings also confirm observations from previous U.S. and international investigations of adolescents concerning the association of sociodemographic characteristics and mental disorders.1
In particular, female adolescents were more likely than males to have mood and anxiety disorders, but less likely to have behavioral and substance use disorders. Non-Hispanic Blacks were less likely to have substance use disorders compared to Whites, a finding that is similar to prior community studies of adolescents and adults.37
The increased prevalence of mood and substance use disorders in older adolescents has also been observed in previous investigations,38
thus indicating the importance of prevention strategies for early and mid-adolescence. By contrast, the stability of certain anxiety and behavioral disorders across this same developmental period suggests that earlier interventions before puberty may be appropriate for many of these conditions.
The strong links between adolescent mental disorders and parental characteristics indicate the importance of the family context in the development of mental disorders. Our finding of a prominent effect of parental education on mental disorders has been well-documented for both child physical and mental health outcomes.39, 40
Divorce was often associated with mental disorders in youth, particularly anxiety, behavior and substance use disorders. The mechanisms underlying the impact of non-intact homes on mental disorders in youth, including both biologic or genetic vulnerability, and indirect influences on disruptions in the home environment, warrant further study.9, 41, 42
However, the significant interactions observed among several sociodemographic characteristics attest to the complexity of these associations. For example, increased rates of substance use disorders among Hispanic adolescents whose parents were divorced may reflect interactions of individual, familial and broader environmental influences that should be considered simultaneously in modeling the nature of risk and resilience in adolescent mental disorders.43, 44
The lack of strong effects for some sociodemographic characteristics, such as poverty, may also be attributable to the multivariate statistical approach that adjusted for confounded variables.
The present findings should be interpreted in the context of several study-specific limitations. First, the cross-sectional nature of the survey limits our ability to document temporal ordering of mental disorders and putative risk and protective factors. Second, assessment of lifetime disorders is based on retrospective recall that is subject to numerous types of bias. Although we employed a number of methods to increase the validity of retrospective reports of age of onset,21
it is unlikely that we were able to completely correct for recall biases. A third limitation is that surrogate information was obtained only from one parent using a self-administered questionnaire rather than a direct interview, and only for a limited number of disorders assessed in the survey. The lack of prior evidence for integrating parent and child reports based on different modes of administration led us to apply an empirical approach based on previous research on cross-informant diagnostic estimates.23
In addition to study-specific limitations, a critical view is warranted concerning current diagnostic nomenclature more generally. Adolescence is a period of change and maturation in which emotional and behavioral difficulties may be common, and it is difficult to establish universally acceptable definitions of disorder or severity thresholds. The high comorbidity across classes of disorders also raises questions regarding the permeability of diagnostic categories and the plasticity of adolescent development. The pertinence of current and alternative developmentally-appropriate diagnostic criteria for adolescent mental disorders deserves careful attention and would benefit from continued debate.
Despite these limitations, our findings document the high prevalence of mental disorders in youth, and specify that just over one in four-to-five adolescents in the general population suffers from disorders that result in severe impairment. Considered with recent estimates indicating that the annual economic burden of mental disorders on the well-being of American youth and their families approaches a quarter of one trillion dollars45
, these findings underscore the key public health importance of mental health in American youth. The present data can inform and guide the development of priorities for future research and health policy by providing previously lacking prevalence estimates in a nationally representative sample of U.S. adolescents, as well as the individual, familial and environmental correlates of mental disorders. Prospective research is now needed to understand the risk factors for mental disorder onset in adolescence, as well as the predictors of the continuity of these disorders into adulthood.