Depression in the community: a comparison of treated and non-treated cases in two non-referred samples.

Family studies in non-patient samples may help to clarify whether or not treatment-seeking behaviour is substantially determined by clinical features of depression. Life-time risks of depression were investigated by structured clinical interviews (SADS-LA) in both a high-risk sample of depressed patients' first-degree relatives and an unscreened control sample of the general population: 34.6% of the high-risk sample versus 23.1% of controls were cases of depression, with a female preponderance in both groups. The rates of treated depression were 17.0% versus 8.5%. Female sex, greater age, higher severity of episodes, manic or hypomanic episodes recurrent course, and introverted and anancastic personality were factors increasing the rate of treated cases in both samples, as well as familial loading with treated depression. Late onset and chronicity of depression did not significantly affect these proportions, but controlling for the effects of retrospective assessment by focusing only on depression within the past year confirmed the results. However, the major finding of a familial influence in treatment-seeking behaviour might be due to a personality factor running in families, as well as to a sharing of common environmental factors.