New Study Challenges Dopamine’s Role in Placebo Pain Relief

Does dopamine determine the strength of pain relief we expect from a pain killer – and drive treatment efficacy?

A recent study has cast doubt on the long-held belief that dopamine, a key neurotransmitter associated with reward and pleasure, plays a direct role in the placebo effect, particularly in pain relief. Researchers from University Hospital Essen in Germany, led by Ulrike Bingel, conducted a randomized trial involving 168 healthy volunteers to explore the neurochemical basis of placebo analgesia. The findings, published on September 24 in the journal PLOS Biology, suggest that dopamine may not be as crucial as previously thought in driving positive treatment expectations and pain relief from placebos.

The study used a placebo pain relief model combined with medications that either increased or decreased dopamine levels: a dopamine antagonist (sulpiride), a dopamine precursor (L-dopa), and a placebo control. Despite successfully altering dopamine levels during the experiment, the researchers found that changes in dopamine did not influence the formation or persistence of placebo pain relief. Placebo-induced pain relief was evident one day after treatment but disappeared by day eight, suggesting dopamine’s minimal impact on these effects.

While dopamine might not be essential for placebo analgesia, the study highlights that dopamine-dependent aspects of reward processing, such as motivation, may still influence the pain experience. These insights could help refine how we understand the complex interactions between brain chemistry, cognition, and treatment outcomes, potentially guiding more effective medical interventions.

“Our research aims to uncover the mechanisms behind placebo effects to enhance active treatments,” the authors stated. “These findings redirect the search for new therapeutic targets.”

For more details, you can access the full study here.