Facilitation of Fear Extinction With Yohimbine Hydrochloride in Phobic Participants

Procedurally Virtual reality exposure therapy (VRET) is quite similar to models of extinction of conditioned fears. Recent advances in animal research have identified pharmacological agents that appear to both accelerate and consolidate extinction learning. One of these cognitive enhancers is Yohimbine. An interesting finding in animal literature is that the administration of Yohimbine during extinction trials accelerates fear reduction and may convert ineffective exposures in to successful ones. It is thought that the mechanism of enhanced emotional memory is through elevated norepinephrine in the prefrontal cortex. Therefore, we propose to extend these studies by combining VRET with Yohimbine. In this pilot study with a between groups design 20 participants with a fear of flying will be treated with VRET plus Yohimbine or VRET plus placebo. This between groups design was chosen to further characterize the differential within and between trial extinction. Outcome will be measured by self-report, behavioral, and psychophysiological assessments at pre- and post-treatment. In addition, we will examine extinction parameters during exposures.

Standard virtual reality exposure therapy for fear of flying will be combined with the administration of either yohimbine hydrochloride or an inactive placebo pill.

Flight Anxiety Situations Questionnaire (self-report); Flight Anxiety Modality Questionnaire (self-report)

Severity of Anxiety Symptoms (Beck Anxiety Inventory) Anxiety Sensitivity (Anxiety Sensitivity Inventory)

Inclusion Criteria: DSM-IV diagnosis of specific phobia (fear of flying). Between the ages of 18-65 Sufficient fluency in Dutch to complete treatment and research protocol Exclusion Criteria: Presence of medical condition, assessed by self-report questionnaires at the intake (i.e., pregnancy, seizure disorder, respiratory disorder, cardiovascular disease, pacemaker, hypertension). Resting blood pressure higher than 140 (systolic) or 105 (diastolic) Unstable psychotropic medication. Current use of tranquilizers (Benzodiazepines) Psychosis Depression with suicidal ideation Dementia or other severe cognitive impairment Substance dependence Bipolar disorder Borderline personality disorder Anti-social personality disorder Current use of beta-blockers