The prognosis of common mental disorders in adolescents: a 14-year prospective cohort study

Summary

Background

Most adults with common mental disorders report their first symptoms before 24 years of age. Although adolescent anxiety and depression are frequent, little clarity exists about which syndromes persist into adulthood or resolve before then. In this report, we aim to describe the patterns and predictors of persistence into adulthood.

Methods

We recruited a stratified, random sample of 1943 adolescents from 44 secondary schools across the state of Victoria, Australia. Between August, 1992, and January, 2008, we assessed common mental disorder at five points in adolescence and three in young adulthood, commencing at a mean age of 15·5 years and ending at a mean age of 29·1 years. Adolescent disorders were defined on the Revised Clinical Interview Schedule (CIS-R) at five adolescent measurement points, with a primary cutoff score of 12 or higher representing a level at which a family doctor would be concerned. Secondary analyses addressed more severe disorders at a cutoff of 18 or higher.

Findings

236 of 821 (29%; 95% CI 25–32) male participants and 498 of 929 (54%; 51–57) female participants reported high symptoms on the CIS-R (≥12) at least once during adolescence. Almost 60% (434/734) went on to report a further episode as a young adult. However, for adolescents with one episode of less than 6 months duration, just over half had no further common mental health disorder as a young adult. Longer duration of mental health disorders in adolescence was the strongest predictor of clear-cut young adult disorder (odds ratio [OR] for persistent young adult disorder vs none 3·16, 95% CI 1·86–5·37). Girls (2·12, 1·29–3·48) and adolescents with a background of parental separation or divorce (1·62, 1·03–2·53) also had a greater likelihood of having ongoing disorder into young adulthood than did those without such a background. Rates of adolescent onset disorder dropped sharply by the late 20s (0·57, 0·45–0·73), suggesting a further resolution for many patients whose symptoms had persisted into the early 20s.

Interpretation

Episodes of adolescent mental disorder often precede mental disorders in young adults. However, many such disorders, especially when brief in duration, are limited to the teenage years, with further symptom remission common in the late 20s. The resolution of many adolescent disorders gives reason for optimism that interventions that shorten the duration of episodes could prevent much morbidity later in life.

Funding

Australia's National Health and Medical Research Council.

Introduction

Adolescence has long been regarded as a time of heightened emotional reactions.1, 2 More than a century ago, Stanley Hall delineated adolescence as a distinct life phase, in which emotional turbulence (or “sturm und drang”) was typical.¹ Early psychoanalysts also viewed emotional turmoil as a universal feature of adolescence but without major implications for later mental health.³ These early views have been much debated in the past 40 years. The first systematic cross-sectional surveys of adolescents suggested that mood disturbances were neither inevitable nor universal.⁴ Far from resolving spontaneously, they tended to predict further distress in the short term.⁵ Moreover, studies in adults suggested that most functional mental disorders seem to begin before the age of 25 years, and often between 11 and 18 years of age.⁶ Later research in young adults with mental disorders also showed high rates of antecedent adolescent depressive and anxiety symptoms.7, 8 Adolescence has therefore come to be seen as a time of vulnerability and the point at which much of the disease burden from mental disorders emerges.⁹

However, the longer term implications of adolescent syndromes remain uncertain. A recent prospective study of mental health and behavioural problems through adolescence showed very high cumulative rates, with more than 60% of participants fulfilling criteria for at least one well-specified disorder in the Diagnostic and Statistical Manual of Mental Disorders at some point between the ages of 9 and 21 years, rising to over 80% if “not otherwise specified” diagnoses were included.¹⁰ Although the experience of a mental disorder seemed to be nearly universal at some point in adolescence, relatively few people were affected at any one point in time.¹⁰ In view of the increasing emphasis on early clinical intervention, understanding of prognosis is central to service planning.¹¹ Similarly, an understanding of prognostic predictors has the potential to inform preventive and early intervention strategies. Some syndromes, such as deliberate self-harm and eating disorders, seem to be mainly limited to adolescence, with few persisting into adulthood.12, 13 So far, the prognosis of episodes of depression and anxiety in adolescents, the largest single contributors to disease burden in this age group, has not been described.

In this report, we use data from the Victorian Adolescent Health Cohort study—a 14-year study of health from the mid-teenage years to the late 20s. Specifically, we address two questions: how often do common mental disorders persist from adolescence to young adulthood? And what are the demographic, behavioural, and disorder characteristics that predict the continuation of such disorders into young adulthood?