Walsh RFL, Sheppard B, Cui L, et al. - In a community-based family study of mood spectrum disorders, researchers investigated the familial aggregation of attention-deficit/hyperactivity disorder (ADHD) and its cross-transmission with bipolar disorder (BD). In this analysis, they included a clinically-enriched community sample of 562 probands from the greater Washington, DC metropolitan area and 698 of their relatives. They used standard family study methodology, confirming DSM-IV classified mental disorders via a best-estimate method based on direct semi-structured interviews and multiple family history reports. Observations revealed specificity of familial aggregation of ADHD and BD with a lack of shared familial risk. This lends support to the notion that the comorbidity between ADHD and BD may be due to diagnostic artifact, could be a separate BD suptype specified by childhood-onset symptoms, or the probability that attention problems serve as a precursor or consequence of BD.