Conditioned Placebo Analgesia Persists When Subjects Know They Are Receiving a Placebo

Abstract

Belief in the effectiveness of a placebo treatment is widely thought to be critical for placebo analgesia. Many types of placebo responses—even those that depend on conditioning—appear to be mediated by expectations that are strengthened as treatment cues are reinforced with positive outcomes. However, placebo effects may occur even when participants are aware they are receiving placebo. To address the question of whether conditioned placebo analgesia can persist in the absence of expectations, we studied the effects of long (4 days) vs. short (1 day) conditioning to a placebo treatment. After an initial placebo test, a “reveal” manipulation convincingly demonstrated to participants that they had never received an active drug. Placebo analgesia persisted after the reveal in the long conditioning group only. These findings suggest that reinforcing treatment cues with positive outcomes can create placebo effects that are independent of reported expectations for pain relief.

Hypoalgesic placebo effects can occur with transparent disclosures

“…These results are also in line with prior research that showed that placebo conditioned hypoalgesic effects persist after revealing that the cream used to reduce the experimental heat pain was merely Vaseline [10]. Therefore, it appears that informing study participants about the precise nature of the placebo manipulation and its mechanisms yields no negative reactions or negative consequences and actually may favor outcome improvements throughout increasing participant engagement.…”

Placebo effects and their determinants in gastrointestinal disorders

“…Although a full discussion of ethical aspects is beyond the scope of this article (reviewed elsewhere 174,175 ), it is important to draw attention to emerging evidence from clinical trials in patients with IBS, 83 major depression 176 and migraine 171 that 'openlabel' placebo treatment might be efficacious and is also supported by experimental data. 177,178 Similarly, application of conditioning principles could pave the way to reduce the amount of medication needed 179,180 and/or to reduce adverse events such as conditioned nausea. 142,181 These improvements in care could be achieved with the informed consent of patients and thereby overcome ethics restraints in this field.…”

Olfactory dining: designing for the dominant sense

“…That is, even though you know that you are using a placebo, it can still work, at least to a certain degree, and under certain conditions [60]. Maybe here the key thing distinguishing the augmenting of the olfactory element of a dish in the modernist restaurant case and that described in the adulterated whiskey (or should/could that read whisky?)…”