Distinguishing early and late onset non-melancholic unipolar depression.

AIM: We seek to determine whether unipolar non-melancholic major depression commencing early in life has a differing clinical picture, and whether it may have differing determinants.
METHODS: We study a sample of such patients, comparing those with depression onset in their first 25 years against residual subjects, matching exactly by sex and controlling for age.
RESULTS: There were no differences in current depression severity. Despite early onset subjects having a distinctly younger current mean age, they had a lifetime pattern of both greater depression chronicity and disability, and judged themselves as less likely to have benefited from any antidepressant medication or psychotherapy. 'Phenotypically' early onset subjects did not differ in terms of 'depressive' symptoms, but were distinguished by a greater irritability, which we interpret as reflecting a temperament dimension influencing symptom expression. Multivariate analyses indicated that the clinical pattern in those with an early onset was distinguished by more evident irritability and anxiety, that there was a distinct familial contribution to early onset depression, that its forerunners were an early personality style of behavioural inhibition or shyness, and that they were more likely to use alcohol and illicit drugs.
CONCLUSIONS: While early onset unipolar depression is unlikely to be a pure depressive 'type', it may well be that certain familial temperament characteristics lead to an early onset of depression marked by irritability, a process that invokes a spectrum disorder concept linking temperament style and the depressive manifestations. Early onset depression is indicative of a poor prognosis, both in terms of response to interventions and in regard to chronicity and disability.