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Is there a delay in the antidepressant effect? A meta-analysis
Michael A Posternak1, Mark Zimmerman
1Department of Psychiatry and Human Behavior, Brown University School of Medicine, Rhode Island Hospital, Providence, RI 02905, USA. mposternak@lifespan.org
The Journal of Clinical Psychiatry
|February 12, 2005
Summary
Antidepressant effects and placebo responses occur rapidly, with most improvement seen within the first two weeks of treatment. This challenges the traditional view of a delayed antidepressant onset, indicating early drug-placebo separation.
Area of Science:
- Psychiatry
- Clinical Psychology
- Pharmacology
Background:
- The traditional view suggests a significant delay before antidepressants exhibit their full therapeutic effect.
- Recent evidence questions the necessity of this prolonged delay for a true antidepressant response.
Purpose of the Study:
- To determine if significant drug-placebo differences emerge within the initial two weeks of treatment.
- To investigate whether the onset of response to antidepressant medications and placebo differs in timing.
Main Methods:
- A meta-analysis of 47 double-blind, placebo-controlled trials evaluating antidepressants with established efficacy.
- Included studies with weekly or biweekly assessments using the Hamilton Rating Scale for Depression.
Main Results:
- The time course of improvement for both active medication and placebo was nearly identical, with the majority of improvement occurring within the first two weeks.
- Clinically observable drug-placebo separation was most pronounced early in treatment and diminished over time, confirming a true drug effect.
Conclusions:
- The findings challenge the long-held notion that a substantial delay precedes the onset of a true antidepressant effect.
- Antidepressant medications demonstrate early efficacy, with significant separation from placebo observed within the first two weeks of treatment.