Is context everything to the definition of clinical depression? A test of the Horwitz and Wakefield postulate.

BACKGROUND

In arguing for the need to distinguish clinical depression from sadness, Horwitz and Wakefield argued for weighting consideration to nuances of life event stressors. Their definition of clinical depression corresponds to the concept of endogenous depression or melancholia, while their model would position reactive (or context specific) non-melancholic depressive disorders more as manifestations of 'sadness' rather than as clinical depression.

METHOD

We test their postulate by examining the extent to which 141 clinically diagnosed melancholic and non-melancholic depressed patients reported episodes as being preceded by a life event stressor or not--and the salience of any life stressor to episode onset and severity.

RESULTS

While melancholic patients were more likely than non-melancholic patients to report episodes coming 'out of the blue' and to be more severe than might be expected from the severity of antecedent stressors, differences were more ones of degree and not absolute. Such context variables appeared, however, to differentiate melancholic and non-melancholic patients more consistently than depression symptom variables. As depression severity and impairment levels did not differ across the melancholic and non-melancholic patients, findings were unlikely to be artefacts of such factors.

CONCLUSIONS

The study finds some support for the Horwitz and Wakefield hypothesis of clinical (or, at least melancholic) depression requiring independence of context or an antecedent stressor, but with precision likely to be compromised by nuances intrinsic to assessment of life event stressors and their contribution to depression onset, difficulties in defining valid 'melancholic' and 'non-melancholic' depressive sub-groups and the parsimony of the hypothesis.