Research has failed to find the expected clear-cut difference in the presence of events provoking onset in endogenous and nonendogenous depression.
A longitudinal study of 127 depressed female patients from two psychiatric departments were studied using the Present State Examination and the Life Event and Difficulty Schedule. Two earlier patient series using the same measures were employed to check findings, and two general population series were used to estimate the expected rate of life events.
A large proportion of patients experienced a severely threatening event before onset, with the exception of a group defined by a British diagnostic category (a relatively small group of patients with melancholic/psychotic depression who were not experiencing their first episode). The results were broadly replicated in the two other patient series. The proportions of patients who experienced ongoing major difficulties did not differ between the groups.
The relative size of this melancholic/ psychotic group of patients with a prior onset may well have varied markedly from study to study in previous research, and this may help to explain the puzzling variability in findings concerning the role of stressful events in endogenous depression.
Brown GW, Harris TO, Hepworth C. Life Events and Endogenous DepressionA Puzzle Reexamined. Arch Gen Psychiatry. 1994;51(7):525-534. doi:10.1001/archpsyc.1994.03950070017006