Cardiovascular reactivity to psychological stress may enhance subsequent pain sensitivity

Stress-induced physiological reactivity has been shown to correlate with indexes of pain sensitivity, but it has not been demonstrated whether such reactivity can affect subsequent levels of pain threshold, tolerance and self-reported severity. The present study examined whether the degree of physiological reactivity (i.e., blood pressure and heart rate) elicited during an initial psychological stressor could be shown to influence indexes of pain sensitivity during subsequent pain induction. Fifty-two undergraduate men and women were assigned randomly to one of two conditions: perform mental arithmetic (MA) and then undergo a cold pressor task (CP; MA/CP) or vice versa (CP/MA). Subjects were divided into low/high mean arterial pressure (MAP) and low/high heart rate (HR) groups based on reactivity to MA. Principal analyses showed 'condition x MAP reactor group' interactions for pain threshold (F(1,48) = 7.38; P < 0.009) and tolerance (F(1,48) = 9.63; P < 0.003). Post hoc tests revealed that high MAP reactors in the MA/CP condition showed lower pain threshold and tolerance during CP than low MAP reactors in the same condition, while high and low MAP reactors in the CP/ MA condition did not differ. Thus, cardiovascular reactivity during psychological stress may contribute to increased sensitivity to subsequent painful stimulation.