Motivation and placebos: do different mechanisms occur in different contexts?

Abstract

This paper challenges the common assumption that the mechanisms underlying short-term placebo paradigms (where there is no motivation for health improvement) and long-term placebo paradigms (where patients value improvement in their health) are the same. Three types of motivational theory are reviewed: (i) classical placebo motivation theory that the placebo response results from the desire for therapeutic improvement; (ii) goal activation model that expectancy-driven placebo responses are enhanced when the placebo response satisfies an activated goal; and (iii) motivational concordance model that the placebo response is the consequence of concordance between the placebo ritual and significant intrinsic motives. It is suggested that current data are consistent with the following theory: response expectancy, conditioning and goal activation are responsible for short-term placebo effects but long-term therapeutic change is achieved through the effects of goal satisfaction and affect on the inflammatory response system and hypothalamic -pituitaryadrenal axis. Empirical predictions of this new theory are outlined, including ways in which placebo effects can be combined with other psychologically mediated effects on short-term and long-term psychological and physiological state.

Choice and placebo expectation effects in the context of pain analgesia

“…Moreover, despite advances in modern medicine, the success of many treatments still depends upon placebo responding, including for depression (Kirsch & Sapierstein 1998), cardiovascular disease (Bienenfeld et al, 1996), and, importantly for the current research, acute and chronic pain (Laska & Sunshine, 1977; for reviews see Harrington, 1999;Kirsch, 1999;Price et al, 2008). Although considerable research has demonstrated placebo effects and their mechanisms, there has been less research on the social psychological factors that determine when such effects are strongest (Hyland, 2011;Price & Fields, 1997). The current research explored whether having choice (vs. not) over a treatment influences placebo responding in the context of pain analgesia (i.e., pain reduction).…”

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

“…In addition, placebo-controlled clinical trials of acupuncture in different painful conditions have shown that both active and placebo acupuncture can lead to marked symptom improvement lasting up to 6 months even in the placebo-treated patients, thereby suggesting that placebo effects maintain over long periods (Brinkhaus et al 2006;Linde et al 2005Linde et al , 2007Melchart et al 2005;Witt et al 2005). Thus, there is reason to believe that placebo effects can last for longer periods and factors like emotions, motivation, expectancy and previous treatment history appear to be central in the maintenance of these effects (Hyland 2011; Overall the literature reviewed in this article suggests that psychosocial placebo components can interact with neurobiological factors and thereby contribute to the efficacy of standard pain treatments. Therefore, it may be very helpful for practitioners to be aware of how placebo components may either enhance or reduce the outcome of active treatment effects in chronic pain patients.…”

Introduction to placebo effects in medicine: mechanisms and clinical implications

“…Starting from a motivational framework of placebo effects, Michael Hyland [32] provides evidence that different placebo mechanisms may apply in different contexts. Whereas response expectancy, conditioning and goal activation may be responsible for short-term placebo effects, long-term placebo responses may be achieved through satisfaction of higher level goals, such as a good relationship with the doctor.…”

“…For example, traits related to reward (and, from a neurobiological point of view, the dopaminergic activation), such as novelty seeking and reward responsiveness, accounted for about 25 to 30% of the variance in placebo analgesic responses [35,36]. Additionally, altruism [37], optimism [38][39][40], empathy [31] and spirituality [32,41] have been found to modulate placebo responses.…”

“…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].…”