Advertisement
Commentaries| Volume 47, ISSUE 8, P733-735, April 15, 2000

Are drug and placebo effects in depression additive?

  • Irving Kirsch
    Correspondence
    Address reprint requests to Irving Kirsh, Ph.D., Professor of Psychology, University of Connecticut, Dept. of Psychology, U-20, Storrs, CT 06269-1020
    Affiliations
    University of Connecticut, Department of Psychology, U-20 Storrs, CT 06269-1020, USA
    Search for articles by this author
      Meta-analyses indicate that between 65% and 80% of the response to antidepressant medication is duplicated by placebos. These data indicate that if the effects of medication and placebos are additive, then the antidepressant drug effect is relatively small; however, data on other drugs indicate that placebo and drug effects are not always additive. Because drug effects are estimated as the difference between the drug response and the placebo response, the assumption of additivity is implicit in conventional clinical trials. The additivity of drug and placebo effects of antidepressant medication needs to be assessed empirically. If these effects are found not to be additive, alternative designs will be needed to assess drug effects.
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'

      Subscribe:

      Subscribe to Biological Psychiatry
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect

      References

        • Antonuccio D.O.
        • Danton W.G.
        • DeNelsky G.Y.
        • Greenberg R.P.
        • Gordon J.S.
        Raising questions about antidepressants.
        Psychother Psychosom. 1999; 68: 3-14
        • Enserink M.
        Can placebo be the cure?.
        Science. 1999; 284: 238-240
        • Fisher S.
        • Greenberg R.P.
        How sound is the double-blind design for evaluating psychotropic drugs.
        J Nerv Ment Dis. 1993; 181: 345-350
        • Joffe R.
        • Sokolov S.
        • Streiner D.
        Antidepressant treatment of depression.
        Can J Psychiatry. 1996; 41: 613-616
        • Kirsch I.
        Changing Expectations. Brooks/Cole, Pacific Grove, CA1990
      1. Kirsch I, Sapirstein G (1999): Listening to Prozac but hearing placebo: A meta-analysis of antidepressant medication. In: Kirsch I, editor. How Expectancies Shape Behavior. Washington, DC: American Psychological Association, 303–320.

        • Kirsch I.
        • Weixel L.J.
        Double-blind versus deceptive administration of a placebo.
        Behav Neurosci. 1988; 102: 319-323
        • Margraf J.
        • Ehlers A.
        • Roth W.T.
        • Clark D.B.
        • Sheikh J.
        • Agras W.S.
        • Taylor C.B.
        How “blind” are double-blind studies?.
        J Consult Clin Psychol. 1991; 59: 184-187
        • Montgomery S.A.
        • Reimitz P.E.
        • Zivkov M.
        Mirtazapine versus amitriptyline in the long-term treatment of depression.
        Int Clin Psychopharmacol. 1998; 13: 63-73
      2. Walach H, Maidhof C (1999): Is the placebo effect dependent on time? A meta-analysis. In: Kirsch I, editor. Expectancy, Experience, and Behavior. Washington, DC: American Psychological Association, 321–332.