Is fear of pain related to placebo analgesia?☆

Abstract 

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)×Five-Test (one pretest, four post-tests) within-subjects design. Heat pain was induced by a 30×30-mm contact thermode to the medial volar forearm. Each pain test lasted for 4 min at a temperature of 46°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.

Keywords: Placebo analgesia, Expectancy, Fear of pain, Stress