The Effect of Mood on Pain: A Laboratory Investigation

Abstract

In accordance with psychological theory and research on pain, depressed mood was hypothesized to decrease tolerance of painful stimulation and elated mood was hypothesized to increase tolerance. Subjects' response to the pain of the cold—pressor task was assessed before and after participation in the Velten mood induction procedure. All subjects who were currently depressed, who exhibited health contraindications for participation in the cold-pressor task, or who exhibited superior pain tolerance, were eliminated from the study. Sixteen men and sixteen women were randomly assigned to either an elated, depressed, or neutral mood induction. The effectiveness of the Velten procedure was assessed by measuring subjects' mood before the induction, after the induction, and at the end of the study. Measures of mood state included three self-report instruments and two behavioural tasks. A significant multivariate analysis of covariance (F(30,122)=4.479, p<0.001) revealed the Velten procedure successfully induced the mood states in subjects. No differences in mood induction response were found for subject gender. As predicted, elated subjects tolerated the painful stimulation longer than the neutral subjects (F(1,88)=9.6, p<.003) who tolerated the cold pain longer than depressed subjects (F(1,88)=12.92, p<.001). Depressed subjects rated their pain as more unpleasant than neutral subjects but elated subjects' unpleasantness ratings did not differ from neutral subjects. As hypothesized, no significant differences were found due to subject gender, or for measures of pain threshold or ratings of pain intensity; however, the pain intensity results were only marginally non-significant. The results strongly support the hypothesis that depressed mood causes a decrease in an individual's ability to tolerate painful stimulation and that elated mood causes an increase in an individual's ability to tolerate painful stimulation. The results also support the hypothesis that depressed mood causes an increase in the unpleasantness of the pain experience. The results did not support the hypothesis that an elated mood reduces the unpleasantness of the pain experience. The hypotheses that pain threshold and the perceived intensity of painful stimulation are not influenced by either depressed or elated mood states only received partial support. The implications for future mood-pain research, particularly laboratory research using the Velten procedure, and the generalizability and limitations of the results, are discussed. Most importantly, the results support the gate-control conceptualization of pain as a multidimensional experience and show that mood states influence the affective more than the sensory dimension of pain.