a1 Department of Health Care Policy, Harvard Medical School, Boston, MA, USA
a2 Division of Developmental Translational Research, National Institute of Mental Health, Bethesda, MD, USA
a3 Division of General Pediatrics, Children's Hospital Boston, Harvard Medical School, Boston, MA, USA
a4 School of Education, Boston University, Boston, MA, USA
a5 Department of Population Medicine, Harvard Medical School, Boston, MA, USA
a6 The Mood and Anxiety Disorders Program, National Institute of Mental Health, Bethesda, MD, USA
a7 Division of Intramural Research Programs, National Institute of Mental Health, Bethesda, MD, USA
Background Research on the structure of co-morbidity among common mental disorders has largely focused on current prevalence rather than on the development of co-morbidity. This report presents preliminary results of the latter type of analysis based on the US National Comorbidity Survey Replication Adolescent Supplement (NCS-A).
Method A national survey was carried out of adolescent mental disorders. DSM-IV diagnoses were based on the Composite International Diagnostic Interview (CIDI) administered to adolescents and questionnaires self-administered to parents. Factor analysis examined co-morbidity among 15 lifetime DSM-IV disorders. Discrete-time survival analysis was used to predict first onset of each disorder from information about prior history of the other 14 disorders.
Results Factor analysis found four factors representing fear, distress, behavior and substance disorders. Associations of temporally primary disorders with the subsequent onset of other disorders, dated using retrospective age-of-onset (AOO) reports, were almost entirely positive. Within-class associations (e.g. distress disorders predicting subsequent onset of other distress disorders) were more consistently significant (63.2%) than between-class associations (33.0%). Strength of associations decreased as co-morbidity among disorders increased. The percentage of lifetime disorders explained (in a predictive rather than a causal sense) by temporally prior disorders was in the range 3.7–6.9% for earliest-onset disorders [specific phobia and attention deficit hyperactivity disorder (ADHD)] and much higher (23.1–64.3%) for later-onset disorders. Fear disorders were the strongest predictors of most other subsequent disorders.
Conclusions Adolescent mental disorders are highly co-morbid. The strong associations of temporally primary fear disorders with many other later-onset disorders suggest that fear disorders might be promising targets for early interventions.
(Received October 26 2011)
(Revised December 23 2011)
(Accepted January 01 2012)
(Online publication January 25 2012)