Bipolar disorder in children and adolescents: international perspective on epidemiology and phenomenology.
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. 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. 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. 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.