Expectations modulate long-term heat pain habituation

Habituation to pain was shown to be a complex mechanism involving the pain encoding regions and the antinociceptive system in the brain. Pain perception can be modulated by cognitive factors; however it is unclear whether cognitive factors also influence habituation to pain. We used an established experimental design with repetitive moderate painful heat stimulation over eight consecutive days. Thirty-seven healthy subjects were recruited and assigned to four different groups: The first group (n = 10) was instructed that pain perception over time will habituate; the second group (n = 9) that pain will increase; the third group (n = 8) was instructed that pain will remain stable over the 8 days of pain stimulation and the fourth group (n = 10) was not given any specific information and served as a control group. We found that the control group habituated as described before. However, it was abolished in the second (sensitize) and third (stable) group, but was very strongly demonstrated in the first (habituation) group. In this group, habituation tended to be increased as compared to the control group. In conclusion, our findings highlight the importance of context information in pain studies and contribute to our knowledge about pain processing and behaviour.