Prevalence, correlates, and course of minor depression and major depression in the National Comorbidity Survey.

Data from the National Comorbidity Survey are used to study the lifetime prevalences, correlates, course and impairments associated with minor depression (mD), major depression 5-6 symptoms (MD 5-6), and major depression with seven or more symptoms (MD 7-9) in an effort to determine whether mD is on a continuum with MD. There is a monotonic increase in average number of episodes, average length of longest episode, impairment, comorbidity, and parental history of psychiatric disorders as we go from mD to Md 5-6 to MD 7-9. In most of these cases, though, the differences between mD and MD 5-6 are no longer than the differences between MD 5-6 and MD 7-9, arguing for continuity between mD and MD. Coupled with the finding from earlier studies that subclinical depression is a significant risk factor for major depression, these results argue that minor depression is a variant of depressive disorder that should be considered seriously both as a target for preventive intervention and for treatment. The paper closes with suggestions regarding the analysis of mD subtypes in future longitudinal studies.