How long does it take for antidepressant therapies to act?

OBJECTIVE: To review the proposition that antidepressants have a delayed onset of action by employing measurement and analytic strategies that overcome problems confounding interpretation of many efficacy studies. METHOD: A subset of patients was recruited to the longitudinal component of the Australasian database study, was assessed at baseline, and then completed measures of depression and anxiety when treatment commenced, and every 3 days over the next 4 weeks. The trajectories of defined 4-week outcome responders and non-responders were compared. RESULTS: Both groups showed a similar decrease in depression (and anxiety) over the first 3 days. A clear trend break then occurred, with little further improvement in the non-responders, as against distinct and progressive improvement in the responders. Ongoing early improvement (across days 3-6) was a strong predictor of responder status. CONCLUSIONS: The small sample size limits firm interpretation, although distinct interpretive advantages to the study design are evident. Findings are compatible with a number of recent studies arguing against any extensive delayed onset of action for the antidepressant drugs, but argue for caution in interpreting immediate improvement as predicting likely responder status, and more for examining early and sustained improvement as such a marker.

Are the newer antidepressant drugs as effective as established physical treatments? Results from an Australasian clinical panel review.

OBJECTIVE: The aim of this study was to determine, in a clinical panel sample, the extent to which patients with depression (and melancholic and non-melancholic subtypes) judged the effectiveness of previously received antidepressant treatments, particularly the comparative effectiveness of the older and newer antidepressant drugs. METHOD: Twenty-seven Australasian psychiatrists assessed 341 non-psychotic depressed patients and rated the extent to which previous antidepressant treatments had been effective. Patients were assigned to 'melancholic' and residual 'non-melancholic' categories by two processes (DSM-IV decision rules, and a cluster analysis-derived allocation) and treatment effectiveness examined within each category. RESULTS: Electroconvulsive therapy (both bilateral and unilateral) was judged as highly effective by both melancholic and non-melancholic patients. Antipsychotic medication similarly rated highly (but was judged as more effective by the non-melancholic than melancholic patients). The tricyclics and irreversible monoamine oxidase inhibitors (MAOIs) were rated as more effective by the whole sample than several newer antidepressant classes (including the selective serotonin re-uptake inhibitors [SSRIs], venlafaxine, mianserin and moclobemide), whether effectiveness was examined dimensionally or categorically. Comparison of the overall tricyclic and SSRI classes indicated that any superior tricyclic effectiveness was specific to the melancholic subjects. CONCLUSIONS: Despite methodological limitations intrinsic to such clinical panel data, the judged greater effectiveness of the older antidepressants (tricyclics and irreversible MAOIs) for melancholic depression is of importance. If valid, such data are of intrinsic clinical relevance but also have the potential to inform us about the neurobiological determinants of 'melancholia' and pharmacological actions which contribute to its effective treatment.