The prevalence of psychiatric disorders is greater than previously thought to be the case. Furthermore, this morbidity is more highly concentrated than previously recognized in roughly one sixth of the population who have a history of three or more comorbid disorders. This suggests that the causes and consequences of high comorbidity should be the focus of research attention. The majority of people with psychiatric disorders fail to obtain professional treatment. Even among people with a lifetime history of three or more comorbid disorders, the proportion who ever obtain specialty sector mental health treatment is less than 50%. These results argue for the importance of more outreach and more research on barriers to professional help-seeking.

Basic epidemiologic prevalence data are presented on sex differences in DSM-III-R major depressive episodes (MDE). The data come from the National Comorbidity Survey (NCS), the first survey in the U.S. to administer a structured psychiatric interview to a nationally representative sample of the general population. Consistent with previous research, women are approximately 1.7 times as likely as men to report a lifetime history of MDE. Age of onset analysis shows that this sex difference begins in early adolescence and persists through the mid-50s. Women also have a much higher rate of 12-month depression than men. However, women with a history of depression do not differ from men with a history of depression in either the probability of being chronically depressed in the past year or in the probability of having an acute recurrence in the past year. This means that the higher prevalence of 12-month depression among women than men is largely due to women having a higher risk of first onset. The implications of these results for future research are discussed in a closing section of the paper.

General population data from the National Comorbidity Survey are presented on co-occurring DSM-III-R addictive and mental disorders. Co-occurrence is highly prevalent in the general population and usually due to the association of a primary mental disorder with a secondary addictive disorder. It is associated with a significantly increased probability of treatment, although the finding that fewer than half of cases with 12-month co-occurrence received any treatment in the year prior to interview suggests the need for greater outreach efforts.

Phobias are common, increasingly prevalent, often associated with serious role impairment, and usually go untreated. Focused research is needed to investigate barriers to help seeking.

This paper reports the results of methodological studies carried out in conjunction with the US National Comorbidity Survey (NCS) to evaluate Version 1.0 of the World Health Organization (WHO) Composite International Diagnostic Interview (CIDItured instrument like the CIDI in the NCS because of the large sample size, the enormous geographic dispersion of the sample, and the prohibitive costs and logistic complications of the study. The NCS was the first large-scale general population survey to administer the CIDI in the United States. Although WHO CIDI Field Trials carried out prior to the NCS documented good performance of the instrument (Wittchen 1994), the field trials were conducted largely in clinical samples and administered in clinical settings. As a result, we considered it very important to carry out pretests before using the instrument in a community sample.As described more fully below, the NCS pretests were guided by the literature on survey data collection methodology (e.g. Bradburn et al. 1979; Moss and 33

Data from a nationally representative sample of the general population are used to study cohort differences in the prevalence of DSM-III-R Major Depressive Episode (MDE). We document increasing lifetime prevalence of MDE among both men and women in more recent cohorts, but no major change in the sex ratio over the 40-year period retrospectively covered in the survey. We find a cohort difference in 12-month MDE, with older women much more likely than older men to have recurrent episodes. This sex difference in recurrence plays an important part in the elevated 12-month prevalence of depression among women compared to men in the 45-54 age range.

These findings suggest a greater burden of major depression in community-dwelling persons than has been estimated from previous community samples. The risk factor profile showed significant differences between persons with pure and combined major depression.

Although life events continue to be the major focus of stress research, recent studies suggest that chronic stress should be a more central focus. An evaluation of this issue is presented using data from a large community survey of married men (n = 819) and women (n = 936). Results show that chronic stresses are more strongly related to depressive symptoms than acute stresses in all but one life domain. The interaction patterns exhibited by chronic and acute stresses are predominantly associated with lower levels of depression than those predicted by a main effects model. This pattern suggests that chronic stresses may reduce the emotional effects of acute stresses. Although the processes through which this effect occurs are not clear, it is suggested that anticipation and reappraisal reduce the stressfulness of an event by making its meaning more benign. Implications for future research on chronic and acute stress effects are discussed.