ONSET OF ACTION UNDER ANTIDEPRESSANT TREATMENT

The issues of timing in antidepressant treatment are of great theoreti cal and practical relevance, even more so since recent meta-analyses y ielded no evidence for a specific mode of action sf antidepressants, w hich, according to the theory of delayed onset of action, is expected to emerge after 2 weeks of therapy. To address the issues of timing on a methodologically sound basis, future trials should adapt a 'longitu dinal' rather than 'cross-sectional' design, standardized with respect to a washout period, baseline and first 2 week assessments. With this in mind, special attention should be paid to parameters which potenti ally enable the identification of placebo responders, true drug respon ders and patients at risk of non-improvement. Results and methods of t he Zurich meta-analyses may serve as a starting point for further step s in this direction.