Epidemiologic studies of adults and children have generally proceeded independently, in part because of differences in diagnostic methods and measures, and the requisite inclusion of informant reports regarding child disorders. One manifestation of this independence is the controversy between what constitutes bipolar disorder in adults and children. There has been substantial debate about whether the rapid mood changes and behavioral dysregulation that characterizes children in clinical samples is truly a manifestation of bipolar disorder that has been fairly well-operationalized in adults.99 There is sparse information on the symptoms of bipolar disorder from community surveys that can address the possible sampling bias in these clinical samples of youth (with the exception of prospective studies such as that of Lewinsohn et al).100
