title: Does yohimbine hydrochloride facilitate fear extinction in virtual reality treatment of fear of flying? A randomized placebo-controlled trial.
abstract: BACKGROUND
  Research suggests that yohimbine hydrochloride (YOH), a noradrenaline agonist, can facilitate fear extinction. It is thought that the mechanism of enhanced emotional memory is stimulated through elevated noradrenaline levels. This randomized placebo-controlled trial examined the potential exposure-enhancing effects of YOH in a clinical sample of participants meeting DSM-IV criteria for a specific phobia (fear of flying).
  
  
  METHODS
  Sixty-seven participants with fear of flying were randomized to 4 sessions of virtual reality exposure therapy (VRET) combined with YOH (10 mg), or 4 sessions of VRET combined with a placebo. Treatment consisted of 4 weekly 1-hour exposure sessions consisting of two 25-minute virtual flights. At pre- and post- treatment, fear of flying was assessed. The YOH or placebo capsules were administered 1 h prior to exposures. The manipulation of the noradrenaline activity was confirmed by salivary α-amylase (sAA) samples taken pre-, during and post-exposure.
  
  
  RESULTS
  Forty-eight participants completed treatment. Manipulation of noradrenaline levels with YOH was successful, with significantly higher levels of sAA in the YOH group when entering exposure. Results showed that both groups improved significantly from pre- to post-treatment with respect to anxiety reduction. However, although the manipulation of noradrenaline activity was successful, there was no evidence that YOH enhanced outcome.
  
  
  CONCLUSIONS
  Participants improved significantly on anxiety measures independently of drug condition, after 4 sessions of VRET. These data do not support the initial findings of exposure-enhancing effects of YOH in this dosage in clinical populations.
authors: Department of Clinical Psychology, University of Amsterdam, Amsterdam, The Netherlands. K.Meyerbroker@uva.nl
authors: Katharina
authors: K
authors: Meyerbroeker
authors: Mark B
authors: MB
authors: Powers
authors: Anda
authors: A
authors: van Stegeren
authors: Paul M G
authors: PM
authors: Emmelkamp
mesh_terms: D000293:Adolescent; D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology / Q000627:therapeutic use*; D000328:Adult; D000337:Aerospace Medicine; D000368:Aged; D000704:Analysis of Variance; D015928:Cognitive Behavioral Therapy; D003131:Combined Modality Therapy; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005108:Extinction, Psychological / Q000187:drug effects*; D005239:Fear / Q000523:psychology; D006801:Humans; D007171:Implosive Therapy / Q000379:methods; D008875:Middle Aged; D009638:Norepinephrine / Q000819:agonists / Q000378:metabolism; D010698:Phobic Disorders / Q000188:drug therapy / Q000523:psychology / Q000628:therapy*; D010919:Placebos; D055291:Salivary alpha-Amylases / Q000032:analysis; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D014584:User-Computer Interface; D015016:Yohimbine / Q000494:pharmacology / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D058669:Adrenergic alpha-2 Receptor Antagonists; D010919:Placebos; D015016:Yohimbine; D055291:Salivary alpha-Amylases; D009638:Norepinephrine