Moreno C et al. – The authors' results support the existence of a spectrum of severity of major depressive episode, with highest severity for bipolar disorder(BD)–I, followed by BD–II and major depressive disorder, suggesting the utility of dimensional assessments in current categorical classifications.

• Data were drawn from the National Epidemiologic Survey on Alcohol and Related Conditions (2001–2002), a nationally representative face-to-face survey of more than 43000 adults in the USA, including 5695 subjects with lifetime MDD, 935 with BD-I and lifetime MDE, and 494 with BD-II and lifetime MDE.
• Differences on sociodemographic characteristics and clinical features, course, and treatment patterns of MDE were analyzed.

• Most depressive symptoms, family psychiatric history, anxiety disorders, alcohol and drug use disorders, and personality disorders were more frequent—and number of depressive symptoms per MDE was higher—among subjects with BD-I, followed by BD-II, and MDD.
• BD-I individuals experienced a higher number of lifetime MDEs, had a poorer quality of life, and received significantly more treatment for MDE than BD-II and MDD subjects.
• Individuals with BD-I and BD-II experienced their first mood episode about ten years earlier than those with MDD (21.2, 20.5, and 30.4 years, respectively).