Re-thinking the treatment of depression: have we been misinformed about antidepressants? A webinar discussion with Irving Kirsch, Ph.D. and Michael D. Yapko, Ph.D

This article provides an edited transcript of a moderated discussion between depression experts Irving Kirsch and Michael Yapko regarding the role of antidepressants in the treatment of major depression. It includes references to the role of expectancy and the merits of hypnosis in treatment. This presentation was sponsored by MindsetHealth, an Australian-based digital therapeutics company (mindsethealth.com) and took place online on March 28, 2023. As a webinar offered at no cost, it was open to anyone with an interest in the subject. Dr. Kirsch described his landmark research on the placebo effect and its curious relationship to the presumed merits of antidepressant medications. Dr. Yapko discussed the limitations of drug treatment based on the substantial evidence indicating that depression is much more a social problem than a medical one. The moderator for this discussion is Claire Davidson, who serves as the Research Lead at MindsetHealth. Drs. Kirsch and Yapko both serve on the MindsetHealth Scientific Advisory Board.

[The role of placebo and nocebo mechanisms in depressive diseases and their treatment]

BACKGROUND

There is substantial evidence that placebo and nocebo effects occur during treatment with antidepressants. A better understanding of the underlying mechanisms of these effects is necessary to optimize the outcome of treatment and to make clinical studies more sensitive.

METHODS

Placebo and nocebo mechanisms were analyzed based on empirical studies and the results are summarized in a narrative review.

RESULTS

Clinical studies and also experimental mechanism-oriented studies underline the effects of placebo and nocebo mechanisms in the treatment with antidepressants.

CONCLUSION

The success of treatment in the use of antidepressants can be increased and the probability of side effects can be reduced by the effective use of placebo mechanisms and reduction of nocebo effects. The results emphasize the influence of clinician-patient interactions, the role of the treatment context and previous experiences with other treatments of the patient. Simultaneously, the results of this research field stimulate a new understanding of mental disorders, in particular depression and also provide points of reference for optimization of psychotherapeutic treatment.

Placebo mechanisms in depression: An experimental investigation of the impact of expectations on sadness in female participants

INTRODUCTION

We aimed to examine whether drug-associated expectations have an impact on the experience of sadness. We hypothesized that participants who received an active placebo nasal spray (but were told that it was an antidepressant that would protect them from experiencing negative emotions) would become less sad than the control groups.

METHODS

128 healthy female participants were randomly allocated to one of four groups: the experimental group, which received an active placebo and the expectancy-modifying instructions ("Protection: the spray protects from experiencing negative emotions", n = 32), or one of three different control groups ("Sensitization": the spray sensitizes to negative emotions", n = 31; "Placebo: the spray is a placebo", n = 32; and "Control: no nasal spray", n = 32) RESULTS: In line with our hypotheses, the experimental group experienced significantly less sadness after having watched a sadness provoking film sequence compared to the three control groups, with medium- to large effect sizes (Hedge´s gs 0.59-0.87).

DISCUSSION

Our results suggest that sadness can be significantly influenced by placebos in the short-term. Our study further suggests that knowledge about the effect of placebos on depressive symptoms should be utilized in clinical practice. However, depression is a complex disorder and antidepressants address a wide range of symptoms associated with depression such as suicidal thoughts, disturbed sleep and loss of energy. Further research on the placebo effects associated with the antidepressant treatment is needed.

LIMITATIONS

concern generalizability to treatment because sadness is only one potential symptom of depression and antidepressants often also address other symptoms.

Psychobiological Mechanisms of Placebo and Nocebo Effects: Pathways to Improve Treatments and Reduce Side Effects

Placebo effects constitute a major part of treatment success in medical interventions. The nocebo effect also has a major impact, as it accounts for a significant proportion of the reported side effects for many treatments. Historically, clinical trials have aimed to reduce placebo effects; however, currently, there is interest in optimizing placebo effects to improve existing treatments and in examining ways to minimize nocebo effects to improve clinical outcome. To achieve these aims, a better understanding of the psychological and neurobiological mechanisms of the placebo and nocebo response is required. This review discusses the impact of the placebo and nocebo response in health care. We also examine the mechanisms involved in the placebo and nocebo effects, including the central mechanism of expectations. Finally, we examine ways to enhance placebo effects and reduce the impact of the nocebo response in clinical practice and suggest areas for future research.

Placebos and the Placebo Effect in Drug Trials

In this review, we explored different ways of controlling the placebo effects in clinical trials and described various factors that may increase/decrease the placebo effect in randomized placebo-controlled trials. These factors can be subdivided into four groups, and while not all factors are effective in every study and under all clinical conditions, they show on the whole that - even under the ideal condition of drug therapy, where blinded placebo provision is much easier and warranted than in, e.g., psychotherapy - many factors need to be controlled to ascertain that the goal of the clinical trials, fair assessment of superiority of the drug over placebo in placebo-controlled trials and fair assessment of non-inferiority of the drug compared to another drug in comparator trials, is reached. Ignorance towards the placebo effect, which was common in the past, is no longer acceptable; instead, it should be the goal of all therapeutic trials to minimize the placebo effect in clinical trials, while utilizing and maximizing it in clinical routine.