title: Opioid antagonist affects behavioral effects of exposure in vivo.
abstract: This study tested the hypothesis that endogenous opioids are involved in the extinction of phobic fear through exposure in vivo. Forty-eight spider phobics participated in a 2-hr therapist-directed exposure in vivo treatment. Sixteen Ss were assigned to placebo, 16 to a low dose of naltrexone, and 16 to a high dose of naltrexone. Before intervention, after treatment, and at a 1-wk follow-up test, self-report, physiological, and behavioral measures of phobic fear were completed. At 1-wk follow-up, naltrexone was significantly related, in a dose-dependent way, to a greater relapse on avoidance measures but not on emotional, cognitive, and physiological measures. Endogenous opioids may be specifically involved in the extinction of avoidance behavior but not in the extinction of all aspects of phobic fear.
authors.affiliation: Department of Medical Psychology, Limburg University, Maastricht, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Arntz
authors.forename: H
authors.initials: H
authors.lastname: Merckelbach
authors.forename: P
authors.initials: P
authors.lastname: de Jong
mesh_terms: D000328:Adult; D000818:Animals; D001143:Arousal / Q000187:drug effects* / Q000502:physiology; D003887:Desensitization, Psychologic; D004305:Dose-Response Relationship, Drug; D004723:Endorphins / Q000502:physiology; D005260:Female; D006801:Humans; D009271:Naltrexone / Q000008:administration & dosage* / Q000009:adverse effects; D010698:Phobic Disorders / Q000188:drug therapy* / Q000503:physiopathology / Q000523:psychology; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology; D013112:Spiders
chemical_list: D004723:Endorphins; D011957:Receptors, Opioid; D009271:Naltrexone