fMRI Study Examining Effects of D-cycloserine in Specific Phobia

An fMRI Study Investigating the Effects of Acute D-cycloserine Administration on Brain Activations and Cognitive Functioning in Spider Phobia.

The research team hopes to use brain imaging and mental testing to learn more about specific phobias and the treatment of phobia. When given directly prior to therapy sessions, D-cycloserine has been shown to enhance the effects of therapy. This study hopes to identify reasons why D-cycloserine has this effect by measuring brain activity.

Exposure and Response Prevention (ERP) therapy has become the treatment of choice for specific phobias. ERP involves systematic and repeated exposure to a feared or anxiety-provoking stimulus, leading to habituation and extinction of the fear response. Animal models of fear extinction have shown that acute administration of D-cycloserine (DCS) prior to exposure to a feared stimulus enhances extinction of that fear. A recent study in human subjects with height phobia (a specific phobia) has also demonstrated that DCS facilitates the effects of ERP therapy. Current theories postulate that DCS facilitates fear extinction by enhancing the learning process and increasing consolidation of memories, but the neural mechanisms underlying this process are not understood. The proposed research aims to elucidate these mechanisms by using fMRI to measure brain activation during 1) symptom provocation and verbal learning two hours post-medication, and 2)repeated symptom provocation and verbal recognition one week post-medication. This research will also examine the effects of DCS on cognitive functioning using neuropsychological testing both two house and one week post-medication.

Inclusion Criteria:

• Right-handed
• Adults between 18 and 55 years of age
• Subjects in the phobic group will additionally meet diagnostic (DSM-IV) criteria for spider phobia.
• Individuals of both genders and all races will be included

Exclusion Criteria:

• Women who are breastfeeding or pregnant
• Individuals with medical conditions unsuitable for MR scanning
• Individuals reporting a history of epilepsy or seizures
• Individuals reporting an allergy to cycloserine
• Individuals diagnosed with asthma or who report previous anaphylactic reaction to insect stings/bites, medication, food, or other material and/or event
• Individuals reporting present or past diagnosis of a developmental disorder, neurological disorder, or head injury *Individuals found to have Axis I psychopathology as defined by the DSM-IV (other than spider phobia)
• Individuals currently taking any psychotropic medication