Background. Minor depression is a disabling condition commonly seen in primary care settings. Although considerable impairment is associated with minor depression, little is known about the course of the illness. Using a variety of clinical and functional measurements, this paper profiles the course of minor depression over a 1 year interval among a cohort of primary care patients.

Method. Patients at a university-based primary care facility were screened for potential cases of depression and selected into three diagnostic categories: an asymptomatic control group; patients with a diagnosis of major depression; and, a third category, defined as minor depression, consisting of patients who reported between two and four symptoms of depression, but who failed to qualify for a diagnosis of major depression. Functional status, service use, and physical, social and mental health were assessed at baseline and at 3-month intervals for the ensuing year.

Results. Respondents with a baseline diagnosis of minor depression exhibited marked impairment on most measures both at baseline and over the following four waves. Their responses in most respects were similar to, although not as severe as, those of respondents with a baseline diagnosis of major depression. Both groups were considerably more impaired than asymptomatic controls.

Conclusions. Minor depression is a persistently disabling condition often seen in primary care settings. Although quantitatively less severe than major depression, it is qualitatively similar and requires careful assessment and close monitoring over the course of the illness.