Opioid antagonist impedes exposure.
Exposure is a rapid and effective treatment for simple phobias. This study tested the assumption that endorphin release may be involved in exposure to a feared situation. Thirty spider-phobic Ss underwent exposure to 17 phobic-related, graded performance tasks. Half the Ss were randomly assigned to naltrexone, an opioid antagonist, and half to a placebo. Measures of heart rate, blood pressure, self-efficacy, anxiety, and cognitions were obtained during treatment. Six of the 15 Ss in the naltrexone group dropped out after the 10th step in the treatment compared with 1 of the 15 Ss in the placebo group, chi 2(1, N = 30) = 4.7, p = .03. The naltrexone group took significantly longer to complete the first 10 steps (the last step that included all Ss) compared with the placebo group, F(9, 252) = 2.17, p = .024. Maximum heart rate and anxiety were significantly greater at Step 10 in the naltrexone group, but no differences were found for self-efficacy or cognitions. The study provides further evidence that the endogenous opioid system may be involved in the process of exposure.
Merluzzi
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TV
University of Notre Dame.
Taylor
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CB
Boltwood
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M
Götestam
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KG
D000328:Adult; D001143:Arousal / Q000187:drug effects / Q000502:physiology; D003887:Desensitization, Psychologic / Q000379:methods*; D004723:Endorphins / Q000502:physiology*; D005239:Fear / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009271:Naltrexone / Q000494:pharmacology; D010555:Personality Inventory; D010698:Phobic Disorders / Q000503:physiopathology* / Q000523:psychology / Q000628:therapy; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*
D004723:Endorphins; D011957:Receptors, Opioid; D009271:Naltrexone