Reduced tolerance and cardiovascular response to ischemic pain in minor depression

Abstract

Background: A paradoxical association between a higher prevalence of clinical pain and a reduced sensitivity to brief experimental pain seems to exist during depression.

Methods: We assessed the responses to sustained ischemic pain produced by a maximal effort tourniquet procedure in 32 controls and 11 individuals with minor depression (Zung autoscale > or =50). Stethoscopic blood pressures and heart rates were monitored throughout the procedure.

Results: Measures of pain threshold, and measures of pain intensity and pain unpleasantness during the ischemic procedure were similar in depressed and control subjects. Yet, the overall numerical ratings of ischemic pain during the procedure was 28% higher and pain tolerance was 44% lower in depressed compared to control subjects. Clinical pain complaints were reported by 91% of depressed but only by 41% of control subjects (P = 0.01). Sustained ischemic pain induced significant elevations of systolic and mean arterial blood pressures in controls but not in depressed subjects.

Limitations: The main limitation of the present study was the preponderance of females in the depressed group. Yet, we did not find significant gender differences in the sensory-affective and autonomic responses to ischemic pain in our sample.

Conclusions: These findings suggest alterations in the sensory and autonomic nervous systems during minor depression.