We updated the design of this site on December 18, 2017. Learn more.
ClinicalTrials.gov Menu

D-Cycloserine to Enhance Cognitive Behavioral Therapy (CBT) for Acrophobia

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
ClinicalTrials.gov Identifier: NCT01102803
Recruitment Status : Completed
First Posted : April 13, 2010
Results First Posted : February 21, 2013
Last Update Posted : February 21, 2013
Information provided by (Responsible Party):
Jasper Smits, Ph.D., Southern Methodist University

Brief Summary:
The purpose of this study is to investigate the utility of post-session administration of D-cycloserine to enhance fear extinction in a sample of people with acrophobia who will be treated with CBT.

Condition or disease Intervention/treatment Phase
Phobic Disorders Behavioral: Individual Cognitive Behavioral Therapy (CBT) Drug: D-Cycloserine Drug: Placebo Phase 3

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 40 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: Evaluation of the Effects of Post-Session Administration of D-cycloserine On Exposure Therapy Outcomes
Study Start Date : April 2010
Primary Completion Date : July 2011
Study Completion Date : July 2011

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Phobias
Drug Information available for: Cycloserine
U.S. FDA Resources

Arm Intervention/treatment
Placebo Comparator: Sugar Pill
Participants will receive placebo augmented cognitive behavioral therapy
Behavioral: Individual Cognitive Behavioral Therapy (CBT)
The aim of CBT is to help participants become more comfortable with heights situations. Participants will receive 2 sessions over two weeks of individual CBT.
Other Names:
  • CBT
  • DCS
Drug: Placebo
Sugar Pill
Experimental: D-Cycloserine
Participants will receive D-Cycloserine augmented cognitive behavioral therapy
Behavioral: Individual Cognitive Behavioral Therapy (CBT)
The aim of CBT is to help participants become more comfortable with heights situations. Participants will receive 2 sessions over two weeks of individual CBT.
Other Names:
  • CBT
  • DCS
Drug: D-Cycloserine

Primary Outcome Measures :
  1. Acrophobia Questionnaire With Avoidance (AAVQ) [ Time Frame: 2 months ]
    Self-report measure that assesses fear and avoidance of a variety of heights situations. This questionnaire (Cohen, 1977) describes 20 situations and assesses levels of avoidance (0-3) and anxiety (0-6). These scales widely used measure of acrophobia with adequate retest reliability (r = .82-.86) and validity (Baker et al., 1973). Higher scores indicate higher levels of avoidance/anxiety (i.e., worse outcome). All subscales are summed for a total score. AAVQ will be assessed at each visit throughout the 2 month protocol. The minimum score is 0, the maximum is 90.

Secondary Outcome Measures :
  1. Attitudes Towards Heights Questionnaire (ATHQ) [ Time Frame: 2 months ]
    Self-report measures that assesses thoughts and feelings towards heights situations. This questionnaire (Abelson and Curtis, 1989) includes six heights situations and assesses attitudes toward these situations using a 0-10 scale. Higher scores indicate a worse outcome and total scores are summed over subscales. Will be assessed at each visit throughout the 2 month protocol. The minimum score is a 0; the maximum is a 60.

  2. Clinical Global Improvement Scale (CGI) [ Time Frame: 2 months ]
    Clinician-rated measure of improvement in acrophobia symptoms and severity. Will be assessed at each visit throughout the 2 month protocol. The CGI-S and CGI-I are widely used measures of global psychopathology severity and improvement initially developed for the study of psychotropic drugs (Guy, 1970). In order to obtain CGI ratings, the therapists (blind to study condition) interviewed the participant and used the SCID (including the specific phobia module) as well as the additional measures of acrophobia symptoms (BAT, AAQ, AAVQ, and ATHQ). In the current study, response was defined as either "very much improved" or "much improved" on CGI-I (score ≤ 2). Remission was defined as either "normal" or "minimally ill" on CGI-S (score ≤ 2). The minimum rating is a 1 and the highest is a 7. Lower scores indicate a better outcome.

  3. Behavioral Avoidance Test (BAT) [ Time Frame: 2 months ]
    During the initial screen, at post-treatment, and at follow-up, participants underwent a behavioral avoidance test in the virtual reality height environment. Participants reported on a 0-100 scale (100 being the most intense fear) their SUDS for floors 1, 2, 3, 4, 9, 19 of the virtual glass elevator and balconies. This test has been used successfully as a measure of treatment gains in previous studies of acrophobia research (Ressler et al., 2004). For the outcome analyses, we included the level of fear reported at the highest floor of the virtual elevator environment (19th floor). Higher scores indicate a worse outcome.

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

Ages Eligible for Study:   18 Years to 65 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  1. Males or females 18-65 years of age with a psychiatric diagnosis of acrophobia defined by DSM-IV criteria.
  2. Willingness and ability to comply with the requirements of the study protocol.

Exclusion Criteria:

  1. A lifetime history of bipolar disorder, schizophrenia, psychosis, delusional disorders or obsessive-compulsive disorder; an eating disorder in the past 6 months; organic brain syndrome, mental retardation or other cognitive dysfunction that could interfere with capacity to engage in therapy; a history of substance (amphetamines, benzodiazepines, barbiturates, cocaine metabolites, marijuana, narcotics, and sedative hypnotics) abuse or dependence or alcohol abuse or dependence (other than nicotine) in the last 6 months or otherwise unable to commit to refraining from alcohol use during the acute period of study participation.
  2. Patients with posttraumatic stress disorder and panic disorder within the past 6 months are excluded. Entry of patients with other mood or anxiety disorders will be permitted in order to increase accrual of a clinically relevant sample. Patients with significant suicidal ideation (MADRS item 10 score > 3) or who have enacted suicidal behaviors within 6 months prior to intake will be excluded from study participation and referred for appropriate clinical intervention.
  3. Patients must be off concurrent psychotropic medication (e.g., antidepressants, anxiolytics, beta blockers) for at least 2 weeks prior to initiation of randomized treatment.
  4. Significant personality dysfunction likely to interfere with study participation.
  5. Serious medical illness or instability for which hospitalization may be likely within the next year.
  6. Patients with a current or past history of seizures.
  7. Pregnant women, lactating women, and women of childbearing potential who are not using medically accepted forms of contraception (e.g., IUD, oral contraceptives, barrier devices, condoms and foam, or implanted progesterone rods stabilized for at least 3 months).
  8. Any concurrent psychotherapy initiated within 3 months of baseline, or ongoing psychotherapy of any duration directed specifically toward treatment of acrophobia is excluded. Prohibited psychotherapy includes CBT therapy focusing on exploring specific, dynamic causes of the phobic symptomatology and provides management skills. General supportive therapy initiated > 3 months prior is acceptable.
  9. Prior non-response to adequately delivered exposure (i.e., as defined by the patient's report of receiving specific and regular exposure assignments as part of a previous treatment) will exclude participants from the study.
  10. Patients with a history of head trauma causing loss of consciousness, seizure or ongoing cognitive impairment.
  11. Patients receiving isoniazid.
  12. Patients unable to understand study procedures and participate in the informed consent process.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT01102803

United States, Texas
Southern Methodist University
Dallas, Texas, United States, 75206
Sponsors and Collaborators
Southern Methodist University
Principal Investigator: Jasper Smits, Ph.D. Southern Methodist University

Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: Jasper Smits, Ph.D., Principal Investigator, Southern Methodist University
ClinicalTrials.gov Identifier: NCT01102803     History of Changes
Other Study ID Numbers: KS09-81
First Posted: April 13, 2010    Key Record Dates
Results First Posted: February 21, 2013
Last Update Posted: February 21, 2013
Last Verified: December 2012

Keywords provided by Jasper Smits, Ph.D., Southern Methodist University:
Anxiety Disorders
Phobic Disorders
Mental Disorders

Additional relevant MeSH terms:
Phobic Disorders
Anxiety Disorders
Mental Disorders
Anti-Infective Agents, Urinary
Anti-Infective Agents
Renal Agents
Antibiotics, Antitubercular
Antitubercular Agents
Anti-Bacterial Agents
Molecular Mechanisms of Pharmacological Action