Placebo analgesia induced by social observational learning

Abstract

Although it has long been known that psychosocial factors play a crucial role in placebo responses, no attempt has been made to understand if social observation shapes the placebo analgesic effect. To address this question, we compared placebo analgesia induced through social observation (Group 1) with first-hand experience via a typical conditioning procedure (Group 2) and verbal suggestion alone (Group 3). In Group 1, subjects underwent painful stimuli and placebo treatment after they had observed a demonstrator (actually a simulator) showing analgesic effect when the painful stimuli were paired to a green light. In Group 2, subjects were conditioned according to previous studies, whereby a green light was associated to the surreptitious reduction of stimulus intensity, so as to make them believe that the treatment worked. In Group 3, subjects received painful stimuli and were verbally instructed to expect a benefit from a green light. Pain perception was assessed by means of a Numerical Rating Scale (NRS) ranging from 0=no pain to 10=maximum imaginable pain. Empathy trait and heart rate were also measured. We found that observing the beneficial effects in the demonstrator induced substantial placebo analgesic responses, which were positively correlated with empathy scores. Moreover, observational social learning produced placebo responses that were similar to those induced by directly experiencing the benefit through the conditioning procedure, whereas verbal suggestions alone produced significantly smaller effects. These findings show that placebo analgesia is finely tuned by social observation and suggest that different forms of learning take part in the placebo phenomenon.

Personality Trait Predictors of Placebo Analgesia and Neurobiological Correlates

“…In our data, this was reflected by positive correlations between agreeableness and m-opioid system activation in several midline regions (subgenual ACC, dorsal ACC and OFC) as well as the anterior and posterior insular cortex, NAc, amygdala and PAG. In this respect, agreeableness has also been linked to greater effectiveness of placebo acupuncture (Kelley et al, 2009) and empathic traits to placebo analgesia mediated through social learning (Colloca and Benedetti, 2009). Moreover, reciprocal altruism has been related to resilience (Charney, 2004) and the activation of brain areas linked to reward processing (Rilling et al, 2002).…”

Hypnosis and top-down regulation of consciousness

“…Despite these inconsistencies, it has been shown that placebo responsiveness, proneness to suggestionbased memory distortions, and hypnotic suggestibility are all associated with empathy (Colloca & Benedetti, 2009;Swider & Babel, 2013;Tomes & Katz, 1997;Wickramasekera & Szlyk, 2003), thereby implying that suggestibility may be related to the broader tendency to be influenced by social contextual cues. In a more extreme form, social cues can function as suggestions that elicit illness, as is the case with mass psychogenic illness (Jones et al, 2000;Mink, 2013).…”

Qualitative study of Nocebo Phenomenon (NP) involved in doctor-patient communication

“…The various possible mechanisms that underlie NP include Pavlovian conditioning, expectations and previous social experiences. In fact both placebo and nocebo responses can be acquired through all kinds of learning and when these happen in the context of everyday clinical practice, these may emanate from either the patient's expectations or their previous similar experiences (4)(5)(6)(7)(8). Neurobiologically, dopamine and endogenous opiates have been shown to serve as the central mediators of these phenomena.…”