A population-based family study of minor depression.

BACKGROUND

There is a paucity of research on whether minor depression is a familial disorder.

METHODS

We conducted a population-based family study of minor depression in which subjects were interviewed using the Diagnostic Interview Schedule (DIS). Minor depression only (MDO) was diagnosed if there was a lifetime history of what the DIS refers to as a depressive "spell" and no lifetime history of either Diagnostic and Statistical Manual of Mental Disorders, Third Edition, major depression or dysthymia. There were 71 probands with a lifetime history of MDO; 577 controls with no lifetime history of MDO, major depression, or dysthymia; and 1,539 first-degree relatives (FDRs). Logistic regression was performed with the presence/absence of MDO in a proband/control as the "exposure" and MDO in an FDR as the "outcome".

RESULTS

The odds ratio for the association between MDO in a proband and MDO in an FDR, after adjusting for age and sex of the FDR, was 1.55 (95% confidence interval: 0.93-2.58; P=.093). The study had 80% power to detect an odds ratio as small as 1.97, which is in the range of odds ratios seen for the familial aggregation of major depression.

CONCLUSIONS

MDO does not appear to be a familial disorder, raising questions about the validity of "minor depression" as a distinct psychiatric syndrome.