Evidence suggests that anger and
pain are related, yet it is not clear by what mechanisms anger may influence
pain. We have proposed that effects of anger states and traits on
pain sensitivity are partly
opioid mediated. In this study, we test the extent to which
analgesic effects of acute anger arousal on subsequent
pain sensitivity are
opioid mediated by subjecting healthy participants to anger-induction and
pain either under
opioid blockade (oral
naltrexone) or placebo. Participants were 160 healthy individuals. A double-blind, placebo-controlled, between-subjects
opioid blockade design is used, with participants assigned randomly to one of two
drug conditions (placebo or
naltrexone), and to one of two Task Orders (anger-induction followed by
pain or vice versa). Results of ANOVAs show significant
Drug Condition x Task Order interactions for sensory
pain ratings (MPQ-Sensory) and angry and nervous affect during
pain-induction, such that participants who underwent anger-induction prior to
pain while under
opioid blockade (
naltrexone) reported more
pain, and anger and nervousness than those who underwent the tasks in the same order, but did so on placebo. Results suggest that for people with intact
opioid systems, acute anger arousal may trigger endogenous
opioid release that reduces subsequent responsiveness to
pain. Conversely, impaired endogenous
opioid function, such as that found among some
chronic pain patients, may leave certain people without optimal buffering from the otherwise hyperalgesic affects of anger arousal, and so may lead to greater
pain and suffering following upsetting or angry events.