The fallacy of the placebo-controlled clinical trials: Are positive outcomes the result of ‘indirect’ treatment effects?

Erik Peper, Richard Harvey


This paper argues that placebo effects have a larger influence and may better explain clinical trial outcomes compared to purported treatment effects currently attributed to clinical treatments.  Placebo-controlled clinical trials usually do not include an ‘active’ placebo and thus the clinical outcome could be due to the placebo responses induced by the non-therapeutic side effects of the treatment.  For this paper, an active placebo includes substances or procedures that permits attribution of a physiological effect such as a B-vitamin that safely causes flushing as well as a biofeedback training procedure that safely trains physiological responses other than the target response.  The paper also discusses the positive outcome of a sham treatment procedure in contrast to the nocebo effect. This paper emphasizes exercising caution when interpreting clinical trials of pharmaceutical or surgical treatments. The paper discusses possible mechanisms underlying the acceptance of treatment procedures which later have been shown to be ineffective or harmful, and highlights the importance of incorporating active placebo procedures to address any covert treatment side effects induced by placebo response. Finally, this paper argues that clinical trials of bio/neurofeedback treatments carefully consider the important and consequential influences of placebos when interpreting the results of trial outcomes.


placebo, nocebo, active placebo, clinical trials, depression

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