Physicians’ beliefs about placebo and nocebo effects in antidepressants – an online survey among German practitioners

by Lea Kampermann, Yvonne Nestoriuc, Meike C. Shedden-Mora

While substantial placebo and nocebo effects have been documented in antidepressant clinical trials, physicians’ awareness of the nonspecific effects in routine antidepressant treatment remains unclear. The study investigated physicians’ beliefs and explanatory models regarding the desired effects and undesired side effects of antidepressants, with specific emphasis on nonspecific effects accounted for by placebo and nocebo mechanisms.

An online survey was conducted among 87 physicians (40.2% psychiatrists, 25.3% neurologists, 24.1% general practitioners, 12.6% internists, 21.8% other). The survey assessed the physician’s beliefs in antidepressant effectiveness, as well as 6 explanatory models regarding antidepressant effectiveness and 8 explanatory models for the occurrence of side effects.

Most physicians (89.7%) believed in the effectiveness of antidepressants while acknowledging a considerable role of the placebo effect by attributing around 40% of the total effects to nonspecific factors. For both antidepressant effectiveness and the occurrence of side effects, pharmacological effects were rated as most important (93.1% and 80.5% agreement), but physicians also attributed a substantial role to the patients’ expectations (63.2% and 58.6%) and experiences (60.9% and 56.3%). Concerning the physician’s own role in promoting nonspecific effects in antidepressant effectiveness, highest endorsements were found for the quality of the physician-patient-relationship (58.6%) and own expectations (41.4%). When asked about side effects, fewer participants agreed that informing the patient about known side effects (25.2%) or the physicians’ expectations themselves (17.2%) could induce side effects.

Physicians, when prescribing antidepressants, are generally open towards nonspecific treatment mechanisms. However, they consider their own influence as less important than the patient’s side, especially when it comes to the explanation of unwanted side effects. Awareness of the possible beneficial as well as malicious role of nonspecific mechanisms should be fostered as the first step towards optimizing antidepressant treatment by promoting placebo while avoiding nocebo effects.