Blood pressure but not cortisol mediates stress effects on subsequent pain perception in healthy men and women

Research has demonstrated that exposure to acute stress may attenuate pain perception. Mechanisms of this effect in humans have not been determined. This study was conducted to determine the extent to which psychophysiological and adrenocortical responses to acute stress predict subsequent pain perception. One hundred and fifty-two healthy participants (80 women) were assigned to one of two conditions: rest followed by the cold pressor test (CPT; N=76) or stress followed by CPT (N=76). The stress protocol consisted of a public-speaking challenge. Participants rated their pain every 15 s during a 90-s hand CPT (0-4°C), and they completed the short form of the McGill Pain Questionnaire. Salivary cortisol, mood, blood pressure (BP), and impedance cardiography measures were collected in both conditions. Women had lower BP and reported greater pain than men in both conditions (ps<0.01). Participants in the stress condition reported less pain during CPT than those in the rest condition (p=0.02). Regression analyses demonstrated that the stress effect on pain ratings was mediated by systolic BP level during stress; however, cortisol responses did not affect this relationship. Mood changes were independent predictors of pain. The study demonstrates that BP changes in response to stress mediate the stress-induced attenuation of pain perception.