Martin M. Katz:  Onset of clinical action of antidepressants

Donald F. Klein’s response (2) to Carlos Morra’s (2) response (to Klein’s response to Carlos Morra’s response) to Klein’s reply to Morra’s comment

In his last response to my response, Carlos Morra asked me to elaborate further on the study of Kasper et al. because it appears to demonstrate antidepressant effects in the first week of medication. My analysis of Kasper’s article will appear on this thread on September 8. It shows Kasper et al. were not pursuing that issue and did not claim there was any such 1 week anti-depressant effect. In fact, the abstract of Kasper et al. begins, “In general, antidepressant drugs are regarded as too slow acting. Most patients who benefit from treatment require more than 2 weeks of therapy to respond to treatment. An efficacious and well-tolerated antidepressant drug with an earlier onset of effect would be of great interest to clinicians and patients.” Kasper’s goal was only to show escitalopram had a faster effect than a pooled group of SSRIs.

 One of the results apparently was thought by Katz to provide evidence of 1 week specific anti-depressant effect. However our analysis showed that the lack of a placebo group led to irretrievable ambiguity.  Further item analyses indicated that the clinically insignificant superiority in onset speed was likely a sedative effect. Therefore, Morra’s question about my analysis of Kasper's article, which implicitly raises the issue if it was supportive of Katz' views was answered in my posting, in the negative.


Kasper S, Spadone C, Verpillat P, Angst J. Onset of action of escitalopram compared with other antidepressants: results of a pooled analysis. Int Clin Psychopharmacol. 2006; 1:105-10.


Donald F. Klein

September 15, 2016