From the Research
The study by Eippert et al. (2009) shows that the placebo effect alters pain responding through activation of the opioid system. This research demonstrated that when participants received a placebo treatment with expectations of pain relief, their endogenous opioid system was activated, leading to reduced pain perception. The opioid system is a natural pain-modulating network in the brain that releases endorphins, which are the body's natural painkillers. When activated during placebo administration, this system can produce genuine analgesic effects by binding to the same receptors that respond to opioid medications. The study used opioid antagonists (drugs that block opioid receptors) to confirm this mechanism, showing that when the opioid system was blocked, the placebo analgesic effect was significantly reduced. This finding helps explain why placebos can produce real physiological changes in pain perception, not just psychological effects, and highlights the importance of expectation and conditioning in pain management approaches 1.
Some key points to consider:
- The opioid system is a complex network that involves multiple receptors, including mu, delta, and kappa receptors, which are targeted by opioid medications and endogenous opioids alike 2, 3.
- The activation of the opioid system by placebo administration can lead to reduced pain perception by releasing endorphins, which are the body's natural painkillers 4.
- The use of opioid antagonists can block the opioid system and reduce the placebo analgesic effect, confirming the role of the opioid system in placebo-induced pain relief 5.
- Recent studies have further elucidated the mechanisms of the placebo effect, including the involvement of other neurotransmitter systems, such as the dopaminergic and serotonergic systems, although the opioid system remains a key player in pain modulation 1, 3.
Overall, the evidence suggests that the opioid system is the primary system involved in the placebo effect's alteration of pain responding, and this knowledge can inform the development of more effective pain management strategies that take into account the complex interplay between psychological and physiological factors 3.