Heart rate and heart rate variability recorded in vivo in agoraphobics and nonphobics

Abstract

Recent advances in technology have made it possible to monitor changes in physiological responses of phobics and other clinical subjects as they encounter real-life, emotion-inducing, situations. In order to assess the characteristics of heart rate as a measure of anxiety in agoraphobia, 10 agoraphobics and 10 matched yoked controls were each given seven repeated in vivo behavioral assessments during which heart rate was monitored. The behavioral test consisted of walking a specified course away from the clinic toward a downtown area. Agoraphobic subjects were given three repeated assessments from 1 to 9 days apart both immediately before and after receiving 12 weeks of exposure-based behavioral treatment for a total of 6 assessments. An additional assessment was administered at the midpoint of therapy. Yoked controls were assessed at identical times but, of course, did not receive treatment. Resting and walking baselines were also administered both before and after the behavioral test. Agoraphobics as a group had significantly higher heart rates than nonphobics both during the test as well as during baselines. In addition, agoraphobics displayed greater lability in heart rate during the walk. However, heart rate in both the treated group and the control group decreased significantly over sessions and there was no significant Group × Session interaction. There were no differences in test-retest reliability in heart rate between groups. For both groups, reliability was quite low. These data illustrate basic differences in physiological responding between agoraphobics and nonphobics but raise questions about the usefulness of physiological assessment as a measure of clinical change in the anxiety disorders.