During the past year, we have continued to investigate the spectrum of mood disorders and mental-physical comorbidity in this national survey of U.S. adults, and to expand our network of collaborators. Mood Disorders: The chief issue that was examined in the NCS-R during the past year was the investigation of the prevalence and clinical correlates of major depressive disorder with subthreshold bipolarity. We found that nearly 40% of study participants with a history of major depressive disorder had a history of subthreshold hypomania. This subgroup had a younger age of disorder onset, more episodes of depression, and higher rates of comorbidity than those without a history of hypomania, and lower levels of clinical severity than those with bipolar II disorder. The findings demonstrate heterogeneity of major depressive disorder and support the validity of inclusion of subthreshold mania in the diagnostic classification. We also investigated the epidemiological characteristics of rapid cycling and non-rapid-cycling bipolar disorder in a large cross-national community sample that included the NCS-R data. The 12-month prevalence of rapid-cycling bipolar disorder was 0.3%, with roughly a third and two-fifths of participants with lifetime and 12-month bipolar disorder respectively meeting criteria for rapid cycling. Compared with the nonrapid-cycling subgroup, rapid-cycling bipolar disorder was associated with younger age at onset, higher persistence, more severe depressive symptoms, greater impairment from depressive symptoms, more out-of-role days from mania/hypomania, more anxiety disorders and an increased likelihood of using health services. Comorbidity of Physical and Mental Conditions: We also investigated the association between mood and anxiety disorders with vascular diseases in the NCS-R. After controlling the effects of obesity, high blood pressure, smoking and diabetes, we found that vascular disease was associated with bipolar disorder in women and major depressive disorder in men. Controlling for anxiety disorders reduced the associations in both men and women, and in fact, anxiety disorders were more strongly associated with vascular diseases in men. These findings demonstrate the importance of evaluation of sex differences, mood disorder subtype and co-occuring anxiety disorders in assessing the association between mood disorders and vascular diseases intervention. These findings are now in press (Fedorowicz et al, in press). We also assessed the independent and joint associations of childhood family adversities and early-onset depression and anxiety disorders with risks of adult-onset headache (Peterlin et al, in press). We found that the association of risk of developing headache was independently associated with both number of childhood family adversities and the presence of early-onset depression/anxiety disorder. Although the etiology of headache remains poorly understood, these results suggest that a broad developmental perspective concerning risk factors for development of severe or frequent headache may be needed to understand how life stressors influence risks in combination with depression and anxiety disorders. The findings call for a broad developmental perspective concerning risk factors for development of headache. Another topic addressed in this study was the association between sleep problems and migraine subtypes in adults. We found that there was a significant association between frequent severe headache, and disordered sleep. Adults with any headache reported more difficulty initiating sleep, staying asleep, early morning awakening and daytime fatigue, and they were twice as likely to report 3 or more of these symptoms compared to those without headache. Headache sufferers are at a significantly higher risk for sleep problems, when compared with the general population, regardless of specific headache type. These finding suggest that optimal headache management must include investigation for sleep difficulties and vice versa. We summarized the magnitude of the prevalence of bipolar disorder in adults and children through a comprehensive review of DSM-IV bipolar disorder in the general population;described the risk factors and correlates of bipolar disorder in community surveys;and described the future directions for the field of epidemiology of bipolar disorder (Merikangas et al). The major finding is the consistency between estimates derived from large population-based studies of adults during the past decade and those reported from earlier reviews. Epidemiologic research during the past decade has contributed new information on the subtypes of bipolar disorder as well as on subthreshold bipolar disorder in general population samples. Evidence suggests that substance use disorders are a consequence of mania, thereby providing an important target for prevention. Bipolar disorder also tends to co-occur with a range of physical disorders, but the causes for this association are not well understood. We identified several contemporary issues that should be addressed in ongoing and future population-based surveys, including the diagnostic thresholds and boundaries of bipolar disorder;the developmental manifestations of bipolar disorder across the lifespan;identification of non-demographic environmental correlates, and potential biologic factors that may index sources of heterogeneity of this disorder;and explanations for nonrandom patterns of comorbidity. Public Health Implications: These findings have major implications for nosology and for clinical practice. Recognition of the importance of subthreshold bipolarity suggests that the diagnostic criteria for mania should be expanded in include evaluation of the spectrum of manifestations of mania rather than solely that which is clinically significant. The strong links between physical and mental disorders, including mood disorders and cardiovascular diseases and migraine with sleep problems and stress-related conditions, highlight the importance of comprehensive medical evaluations of people with mood and anxiety disorders in clinical decision making.
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