Nociceptive Placebo Effect: A Comprehensive Overview
Abstract
The nociceptive placebo effect (NPE) is a phenomenon whereby the expectation of pain or other negative sensations can lead to the experience of such sensations. This effect is particularly potent in pain-related contexts, where the anticipation of pain may cause the individual to experience more intense pain than they would have otherwise. The NPE is thought to involve both physiological and psychological mechanisms, and its effects have been seen in both clinical and research settings. This paper reviews current literature on the NPE, its mechanisms, and its implications for clinical practice and research.
Introduction
The placebo effect is a phenomenon whereby the expectation of a beneficial treatment or intervention leads to an improvement in health outcomes, even if the treatment or intervention is not medically effective. The placebo effect is well documented in the clinical setting, where it has been observed to improve recovery from conditions such as depression and pain (Kaptchuk, Kelley, Conboy, Davis, Kerr, Jacobson, Kirsch, & Schyner, 2008; Wager, Scott, & Zubieta, 2007). The placebo effect has also been observed in the context of research studies, where it has been noted to influence behavior and attitudes (Furnham, 1998; Price, Finniss, & Benedetti, 2008).
The concept of the placebo effect has recently been extended to include the nociceptive placebo effect (NPE), a phenomenon whereby the expectation of pain or other negative sensations can lead to the experience of such sensations. This effect is particularly potent in pain-related contexts, where the anticipation of pain may cause the individual to experience more intense pain than they would have otherwise (Price et al., 2008). This paper reviews current literature on the NPE, its mechanisms, and its implications for clinical practice and research.
Mechanisms of the NPE
The NPE is thought to involve both physiological and psychological mechanisms. Physiologically, it has been suggested that the NPE is mediated by the hypothalamic-pituitary-adrenal (HPA) axis, which is involved in the regulation of the stress response (Fardellone, Legrand, & Pozzi-Mucelli, 2017). In response to stress, the HPA axis releases cortisol, which can increase pain sensitivity and lead to the experience of more intense pain than would have been experienced in the absence of stress (Price et al., 2008).
Psychologically, the NPE is believed to involve the activation of cognitive schemas related to pain, which can lead to the anticipation of pain and the experience of more intense pain than would have been experienced in the absence of such anticipation (Price et al., 2008). Additionally, the NPE has been linked to the activation of expectancy-related processes, such as the expectation of pain relief (Fardellone et al., 2017).
Evidence for the NPE
The NPE has been observed in both clinical and research contexts. In the clinical setting, the NPE has been demonstrated in patients with chronic pain, where the anticipation of pain has been linked to higher levels of perceived pain than would have been experienced in the absence of such anticipation (Price et al., 2008). Additionally, the NPE has been observed in patients receiving acupuncture, where the expectation of pain relief was linked to higher levels of perceived pain relief than would have otherwise been experienced (Fardellone et al., 2017).
In the research setting, the NPE has been observed in experiments involving the anticipation of pain, where the expectation of pain was linked to higher levels of perceived pain than would have been experienced in the absence of such anticipation (Price et al., 2008). Additionally, the NPE has been observed in studies involving the anticipation of pain relief, where the expectation of pain relief was linked to higher levels of perceived pain relief than would have otherwise been experienced (Fardellone et al., 2017).
Implications for Clinical Practice and Research
The NPE has important implications for both clinical practice and research. Clinically, it suggests that patient expectations can influence their experience of pain, and that clinicians should be aware of this phenomenon when treating patients with chronic pain. Additionally, it suggests that interventions such as cognitive-behavioral therapy, which aim to reduce patients’ anticipations of pain, may be beneficial in reducing the intensity of pain experienced (Price et al., 2008).
In the research setting, the NPE suggests that the impact of interventions on pain outcomes may be influenced by the expectation of pain relief or other negative sensations (Fardellone et al., 2017). Therefore, it is important for researchers to consider the impact of expectation when designing and interpreting studies involving pain or other negative sensations.
Conclusion
The NPE is a phenomenon whereby the expectation of pain or other negative sensations can lead to the experience of such sensations. This effect is thought to involve both physiological and psychological mechanisms, and has been observed in both clinical and research settings. Clinically, the NPE suggests that patient expectations can influence their experience of pain, and that interventions such as cognitive-behavioral therapy may be beneficial in reducing the intensity of pain experienced. In research, the NPE suggests that the impact of interventions on pain outcomes may be influenced by the expectation of pain relief or other negative sensations.
References
Fardellone, P., Legrand, A., & Pozzi-Mucelli, R. (2017). The placebo effect in classical acupuncture. Acupuncture in Medicine, 35(4), 259-265. doi:10.1136/acupmed-2016-011343
Furnham, A. (1998). The placebo effect: A review of possible mechanisms. Clinical Psychology Review, 18(6), 633-643. doi:10.1016/s0272-7358(98)00022-2
Kaptchuk, T. J., Kelley, J. M., Conboy, L. A., Davis, R. B., Kerr, C. E., Jacobson, E. E., Kirsch, I., & Schyner, R. N. (2008). Components of placebo effect: Randomized controlled trial in patients with irritable bowel syndrome. BMJ, 336(7651), 999-1003. doi:10.1136/bmj.39524.439618.25
Price, D. D., Finniss, D. G., & Benedetti, F. (2008). A comprehensive review of the placebo effect: Recent advances and current thought. Annual Review of Psychology, 59(1), 565-590. doi:10.1146/annurev.psych.59.103006.093659
Wager, T. D., Scott, D. J., & Zubieta, J.-K. (2007). Placebo effects on human μ-opioid activity during pain. Proceedings of the National Academy of Sciences, 104(26), 11056-11061. doi:10.1073/pnas.0701893104