Psychological Medicine

Original Articles

Evidence that bipolar disorder is the poor outcome fraction of a common developmental phenotype: an 8-year cohort study in young people

M. J. A. Tijssena1, J. van Osa1a2, H.-U. Wittchena3a4, R. Lieba4a5, K. Beesdoa3, R. Mengelersa1, L. Krabbendama1 and M. Wichersa1 c1

a1 Department of Psychiatry, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University, Maastricht, The Netherlands

a2 Division of Psychological Medicine, Institute of Psychiatry, London, UK

a3 Institute of Clinical Psychology and Psychotherapy, Technische Universität Dresden, Dresden, Germany

a4 Max Planck Institute of Psychiatry, Clinical Psychology and Epidemiology Unit, Munich, Germany

a5 Institute of Psychology, Epidemiology and Health Psychology, University of Basel, Switzerland

Abstract

Background Reported rates of bipolar syndromes are highly variable between studies because of age differences, differences in diagnostic criteria, or restriction of sampling to clinical contacts.

Method In 1395 adolescents aged 14–17 years, DSM-IV (hypo)manic episodes (manic and hypomanic episodes combined), use of mental health care, and five ordinal subcategories representing the underlying continuous score of (hypo)manic symptoms (‘mania symptom scale’) were measured at baseline and approximately 1.5, 4 and 10 years later using the Munich-Composite International Diagnostic Interview (DIA-X/M-CIDI).

Results Incidence rates (IRs) of both (hypo)manic episodes and (hypo)manic symptoms (at least one DSM-IV core symptom) were far higher (714/105 person-years and 1720/105 person-years respectively) than traditional estimates. In addition, the risk of developing (hypo)manic episodes was very low after the age of 21 years [hazard ratio (HR) 0.031, 95% confidence interval (CI) 0.0050–0.19], independent of childhood disorders such as attention deficit hyperactivity disorder (ADHD). Most individuals with hypomanic and manic episodes were never in care (87% and 62% respectively) and not presenting co-morbid depressive episodes (69% and 60% respectively). The probability of mental health care increased linearly with the number of symptoms on the mania symptom scale. The incidence of the bipolar categories, in particular at the level of clinical morbidity, was strongly associated with previous childhood disorders and male sex.

Conclusions This study showed, for the first time, that experiencing (hypo)manic symptoms is a common adolescent phenomenon that infrequently predicts mental health care use. The findings suggest that the onset of bipolar disorder can be elucidated by studying the pathway from non-pathological behavioural expression to dysfunction and need for care.

(Received September 21 2008)

(Revised April 08 2009)

(Accepted May 04 2009)

(Online publication June 11 2009)

Correspondence

c1 Address for correspondence: Dr M. Wichers, Department of Psychiatry, Maastricht University, PO Box 616 (Vijverdal), 6200 MD Maastricht, The Netherlands. (Email: m.wichers@sp.unimaas.nl)

Metrics