PSYCHOPHYSIOLOGICAL ASSESSMENT OF STRESS IN CHRONIC PAIN - COMPARISONS OF STRESSFUL STIMULI AND OF RESPONSE SYSTEMS

Due to disparate findings across the published studies, the stress-hyp eractivity hypothesis has never been fully accepted as a causal mechan ism for chronic muscle pain. Two recent comprehensive reviews of the p sychophysiological studies of chronic pain came to opposite conclusion s about the viability of the hypothesis, which stemmed from differing importance placed on the experimental methodology: the adequacy of str ess manipulation. The present study tested the hypotheses that the ade quacy of stress manipulation is influenced by stress stimuli type, deg ree of personal relevance, and selection of criterion for verification of stress experience, and that these factors have a measurable impact on the related physiological responses in a manner that is consistent with a theory of stress applicable to clinical stress disorders. The three factors investigated were: task (imagery, reaction time), releva nce (high, low), and manipulation criterion (autonomic, self-report). The tasks were presented to 16 chronic pain patients while muscle, ele ctrodermal, and self-report responses were recorded. Reaction-time tas ks and high-relevance conditions led to high muscle and electrodermal responses. Only the high-relevance imagery, however, produced high sel f-reported distress. Consistent with other research, the present overa ll data demonstrated differing physiological profiles for different st imuli types. More importantly, these data suggest that the manipulatio n type and the manipulation criterion influence outcomes of experiment al tests of stress on physiological systems, which may directly lead t o contrasting conclusions about causal relations between stress and ch ronic pain conditions.