Objective: There is considerable skepticism outside the US over the prevalence of pediatric bipolar disorder (BD). We wished to evaluate the epidemiology of BD in children and adolescents in non-US samples.
Method: We reviewed studies on the prevalence of BD in children and adolescents in international samples. We also describe our sample of 27 children with BD at the University of Navarra.
Results: There are important and frequently overlooked differences in the definition of BD between the International Classification of Diseases 10th edition (ICD-10) and DSM-IV and methodological differences in epidemiological studies that may partially explain international differences in prevalence of pediatric BD. The prevalence of bipolar spectrum disorder in young adults in Switzerland is 11%. In Holland the 6-month prevalence of mania in adolescents was 1.9% and of hypomania 0.9%. Only 1.2% of hospitalized youth (<15 years) in Denmark and 1.7% of adolescents in Finland had BD. In our clinic, the prevalence of DSM-IV BD in children 5–18 years old is 4%, and of any mood disorders 27%. There are also data from Brazil, India and Turkey with varying results.
Conclusion: Relative lack of data, ICD-10 and DSM-IV differences in diagnostic criteria, different levels of recognition of Child and Adolescent Psychiatry as a true specialty in Europe, clinician bias against BD, an overdiagnosis of the disorder in USA and/or a true higher prevalence of pediatric BD in USA may explain these results. US–International differences may be a methodological artifact and research is needed in this field.