Is fear of pain related to placebo analgesia?

Objective: Verbal information that a painkiller has been administered generates an expectation of pain relief which in turn decreases pain. This expectation-based pain reduction is termed placebo analgesia. We hypothesized that fear of pain would be related to higher stress and pain intensity and to reduced placebo analgesia.

Methods: Sixty-three students (30 females) participated in a Two-Condition (placebo, natural history)xFive-Test (one pretest, four post-tests) within-subjects design. Heat pain was induced by a 30x30-mm contact thermode to the medial volar forearm. Each pain test lasted for 4 min at a temperature of 46 degrees C. Stress, arousal, and pain intensity and pain unpleasantness were rated on 100-mm visual analogue scales.

Results: Fear of pain was related to higher anticipatory stress and to higher stress and pain intensity during pain. Fear of pain was also related to reduced placebo analgesic responding.

Conclusion: Fear of pain was positively related to stress both during pain and in the anticipation of pain, and negatively related to placebo analgesia. Previous research has indicated a role for increased stress in the nocebo response, and the present findings suggest that decreased stress may strengthen the placebo response.