Does the chronological relationship between the onset of dysthymia and major depression influence subsequent response to antidepressants?

OBJECTIVE

To determine whether the chronological relationship between the onset of dysthymia and the onset of the first major depression influences treatment outcome in patients with double depression (DD).

METHOD

Clinical and outcome measures previously collected in 77 consecutive outpatients who presented with major depression and who had pre-existing dysthymia (i.e. DD) were reviewed for the current retrospective analysis. Subjects had been administered the Schedule for Affective Disorders and Schizophrenia, Lifetime Version (SADS-LV), and the Hamilton Rating Scale for Depression (HAM-D) prior to open antidepressant treatment and after 5 and 12 weeks of therapy. Response was defined as a 50% decline in HAM-D to score +/-8. Subjects were divided into those with the onset of dysthymia before the first major depression (DysB; n = 47), onset of dysthymia after major depression (DysA; n = 12) and those with onset of both condition within 2 years of each other (INDIST; n = 18).

RESULTS

There were no significant differences between these three groups in baseline HAM-D. However, DysA subjects had significantly higher mean HAM-D scores than the DysB subjects at week 5 and the INDIST subjects at week 12. Response rates at week 12 were lower in subjects with DysA (33%) as compared with DysB (57%; Fisher's exact test, P = 0.06) and INDIST (78%; Fisher's Exact test P = 0.02).

CONCLUSIONS

These findings suggest that the onset of the first episode of dysthymia after the first major depressive episode (i.e. DysA) may adversely affect response to subsequent treatments in patients with DD.