Naltrexone renders one-session exposure therapy less effective: a controlled pilot study

UMMS Affiliation

Department of Medicine, Division of Preventive and Behavioral Medicine

Publication Date


Document Type



Adolescent; Adult; Combined Modality Therapy; Drug Administration Schedule; Escape Reaction; Fear; Female; Humans; Interviews as Topic; Male; Naltrexone; Narcotic Antagonists; Phobic Disorders; Pilot Projects; Psychotherapy; Severity of Illness Index


Behavioral Disciplines and Activities | Behavior and Behavior Mechanisms | Community Health and Preventive Medicine | Preventive Medicine


In vivo exposure has become the gold standard treatment for specific phobia. The endogenous opioid system is one mechanism proposed to explain why exposure provides such quick and effective treatment for specific phobia. The effect of naltrexone on fear and avoidance behavior was investigated among 15 specific phobia participants who received exposure treatment. Participants were randomly assigned to receive naltrexone, placebo, or no drug prior to attending one-session exposure treatment. Mixed effects regression results revealed that across time, the naltrexone group tolerated significantly less time in the room with the feared animal (Behavioral Avoidance Index) as compared to the placebo and no drug groups. Phobic individuals assigned to the naltrexone group had significantly higher fear ratings across time in comparison to the placebo group. Results provide support for the endogenous opioid system as a potential underlying biological mechanism associated with behavioral changes during in vivo exposure.

DOI of Published Version



J Anxiety Disord. 2007;21(1):142-52. Epub 2006 May 2. Link to article on publisher's site

Journal/Book/Conference Title

Journal of anxiety disorders

Related Resources

Link to Article in PubMed

PubMed ID