Faculty Bibliography

OBJECTIVE:Meta-analyze all published epidemiologic studies reporting pediatric mania or bipolar disorder to investigate whether pediatric bipolar disorder is becoming more prevalent and whether rates vary significantly by country. DATA SOURCES/METHODS:Searches of PubMed and PsycInfo were conducted through the spring of 2010 using the following search terms: child, pediatric, young, adolescent, epidemiology, prevalence, bipolar, mania, suicide, and psychiatric. We also manually reviewed references in recent reviews of epidemiology of bipolar disorder. STUDY SELECTION/METHODS:All studies reporting rates for mania or hypomania in community epidemiologic samples with participants up to 21 years of age. DATA EXTRACTION/METHODS:All articles were coded to extract relevant variables. Prevalence rates were calculated from reported number of cases with bipolar disorders, then logit transformed. Twelve studies were included, enrolling 16,222 youths between the ages of 7 and 21 years during a period from 1985 to 2007. Six samples were from the United States; 6 were from other countries (the Netherlands, the United Kingdom, Spain, Mexico, Ireland, and New Zealand). RESULTS:The overall rate of bipolar disorder was 1.8% (95% CI, 1.1%-3.0%). There was no significant difference in the mean rates between US and non-US studies, but the US studies had a wider range of rates. The highest estimates came from studies that used broad definitions and included bipolar disorder not otherwise specified. Year of enrollment was negatively correlated with prevalence (r = -0.04) and remained nonsignificant when controlling for study methodological differences. CONCLUSIONS:Mean rates of bipolar disorder were higher than commonly acknowledged and not significantly different in US compared to non-US samples, nor was there evidence of an increase in rates of bipolar disorder in the community over time. Differences in diagnostic criteria were a main driver of different rates across studies.

BACKGROUND:Four subtypes of bipolar disorder (BP) - bipolar I, bipolar II, cyclothymia and bipolar not otherwise specified (NOS) - are defined in DSM-IV-TR. Though the diagnostic criteria for each subtype are intended for both adults and children, research investigators and clinicians often stray from the DSM when diagnosing pediatric bipolar disorder (PBD) (Youngstrom, 2009), resulting in a lack of agreement and understanding regarding the PBD subtypes. METHODS:The present study uses the diagnostic validation method first proposed by Robins and Guze (1970) to systematically evaluate cyclothymic disorder as a distinct diagnostic subtype of BP. Using a youth (ages 5-17) outpatient clinical sample (n=827), participants with cyclothymic disorder (n=52) were compared to participants with other BP spectrum disorders and to participants with non-bipolar disorders. RESULTS:Results indicate that cyclothymic disorder shares many characteristics with other bipolar subtypes, supporting its inclusion on the bipolar spectrum. Additionally, cyclothymia could be reliably differentiated from non-mood disorders based on irritability, sleep disturbance, age of symptom onset, comorbid diagnoses, and family history. LIMITATIONS/CONCLUSIONS:There is little supporting research on cyclothymia in young people; these analyses may be considered exploratory. Gaps in this and other studies are highlighted as areas in need of additional research. CONCLUSIONS:Cyclothymic disorder has serious implications for those affected. Though it is rarely diagnosed currently, it can be reliably differentiated from other disorders in young people. Failing to accurately diagnose cyclothymia, and other subthreshold forms of bipolar disorder, contributes to a significant delay in appropriate treatment and may have serious prognostic implications.

The idea of a "bipolar spectrum" is controversial due to 1) lack of widely accepted definitions, 2) concern that spectrum definitions might subsume cases with non-bipolar disorders, 3) worry that "diagnostic creep" may lead practitioners to overdiagnose bipolar disorder in marginal cases, and 4) worry that more diagnosis of bipolar spectrum may increase aggressive pharmacotherapy. These concerns are weighed against theoretical and empiric evidence converging in support of the bipolar spectrum as having prognostic and prescriptive validity. Practitioners can use inexpensive and practical strategies to incorporate the spectrum concept into their work while minimizing risks of overdiagnosis or unnecessary medication exposure.