Background: Although not as common as major depressive disorder, dysthymia is not rare and is associated with substantial impairment. Antidepressants and some psychotherapies are often effective. We explored the efficacy of the antidepressant duloxetine, a serotonin and norepinephrine reuptake inhibitor.
Method: Between February 2005 and April 2006, we recruited 24 adults with DSM-IV dysthymia or dysthymia and concurrent major depression ("double depression") who had an entry score of > or = 17 on the clinician-rated Inventory for Depressive Symptomatology (IDS-C). We excluded subjects with significant medical illnesses and those requiring other psychotropic agents or undergoing psychotherapy. Subjects received duloxetine 60 mg/day for 6 weeks, increased as tolerated to 120 mg/day for the remainder of the 12-week trial for those with an inadequate treatment response.
Results: The subjects' mean +/- SD IDS-C scores decreased significantly from baseline (27.3 +/- 6.3) to endpoint (7.8 +/- 7.4, Student t = 12.38, df = 23, p < or = .001). The IDS-C response rate (intent-to-treat [ITT]) was 83% (20/24); the remission rate (ITT) was 79% (19/24). Among study completers, these rates were 89% (17/19) and 84% (16/19). Five subjects (21%) discontinued for side effects.
Conclusion: Duloxetine appears to be an effective and well-tolerated treatment for dysthymia and double depression. A double-blind, placebo-controlled study is under way. If duloxetine is found to be effective, studies powered to detect potential, clinically important differences between duloxetine and other antidepressants will be needed.
Clinical trials registration: ClinicalTrials.gov identifier NCT00185575.