Severity of stressful life events in first and subsequent episodes of depression: the relevance of depressive subtype

Background: Recent studies have reignited debate concerning the relationship between stressful life events and depressive subtypes, particularly in relation to first versus subsequent episodes. Aims: To investigate the relationship between stressful life events and variably defined melancholic/non-melancholic depressive subtypes, and the import of such life events to first compared with subsequent episodes across those subtypes. Method: Acute and chronic stressful life events were rated in 270 patients with DSM-IV Major Depressive episodes who were allocated to melancholic and non-melancholic groups separately as defined by DSM-III-R, DSM-IV, the Newcastle criteria and the CORE system. Results: Severe stressful life events (both acute and chronic)—as defined by DSM-III-R axis IV—were more likely to occur prior to first rather than subsequent episodes, particularly for those with non-melancholic depression. Limitations: Dependence or independence of life events was not assessed. Genetic vulnerability to depression was not determined. Life events in first and subsequent depressive episodes were compared cross-sectionally between groups, not prospectively in the same cohort of patients. There were no differences in the number of severe life events—as defined by clinician consensus—between the first and subsequent episodes. Conclusions: These findings are consistent with other studies in suggesting an enhanced sensitisation of depressed patients to subsequent episodes of depression, but suggest that any such phenomenon is specific to non-melancholic depression, in comparison to one key previous study.