The relation of emotions to placebo responses

Abstract

The hypothesis put forth is that expectations of treatment effects reduce negative emotions and thereby reduce symptoms, e.g. pain. Negative emotions increase pain, and it is hypothesized that placebos reduce pain by reducing negative emotions, i.e. feelings of nervousness, fear and anxiety. Placebo analgesia has been shown to be mediated via opioid activity, and relaxation increases opioid activity. The placebo acquires its relaxing effect due to verbal information that pain will be reduced, or due to associations between the placebo and the reduction in pain after effective treatment. Thus, the placebo signals that unpleasantness will be less after administration of the placebo. This involves negative reinforcement which is due to activation of a dopaminergic system that has been found to be activated during placebo analgesia and is involved in positive emotions. The nocebo effect of increased pain is, consistent with this model, because of increased fear and anxiety. The new aspect of the presented model is the hypothesis that expectations reduce negative emotions, and that negative reinforcement that involves the dopaminergic reinforcement system should be a contributor to placebo responses.

Placebo effects in children: a review

“…Hypnotic and other suggestibility (54), dispositional optimism (55), the locus of control (56), negative emotions such as fear and anxiety (57), and other psychometric characteristics have never been tested with respect to placebo responses in children and adolescents. However, it is well established that personality, coping characteristics, and outcome expectancies (e.g., negative expectancies, low self-efficacy, and locus of control) codetermine health behavior (58) and outcome of interventions (59) in a rather complex manner in chronic conditions.…”

Placebo effects in chronic pain conditions. Can placebo components enhance the efficacy of active treatments?

“…Research including both healthy volunteers and chronic pain patients indicate that positive and negative emotions are also involved in placebo effects (Flaten et al 2006;Flaten, Aslaksen, Lyby & Bjørkedal 2011;Petersen et al 2012Petersen et al , 2014Vase, Robinson, Verne & Price 2005). A number of studies have, for example, shown that high levels of negative emotions like stress and fear reduce or abolish placebo effects (Lyby, Aslaksen & Flaten 2010;Lyby, Forsberg, Åsli & Flaten 2012).…”

Introduction to placebo effects in medicine: mechanisms and clinical implications

“…Inspired by the insights stemming from hypnosis research, Kirsch [26] wondered about the underlying psychological function determining the specific response to a suggestion, and he began to focus on the role of expectancy as a mediating psychological variable. The importance of verbal suggestions and expectations for placebo and nocebo effects has meanwhile been demonstrated in numerous experimental studies [22,[27][28][29]. Furthermore, there is now compelling evidence for the validity of classical conditioning theory for explaining placebo effects, because drug-like effects also occur when active treatments administered repetitively are replaced with pharmacological inert interventions such as saline solutions or sugar pills [24,27,30].…”

“…Flaten et al [29] review the literature with respect to a hypothesis that focuses on the role of emotions for the placebo response. The hypothesis predicts that pain relief following the ingestion of a placebo pill may be due to the reduction of stress and anxiety and a concomitant increase in positive emotions.…”

“…Recent studies have additionally demonstrated that social observational learning represents another psychological mechanism for producing placebo responses [31]. Further important pieces of the placebo puzzle still need to be integrated into the whole picture, for example, motivational aspects [32], emotions [29] and characteristics of the healing ritual itself [33].…”