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Use of an Antibiotic as an Enhancer for the Treatment of Social Phobia

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. Identifier: NCT00128401
Recruitment Status : Completed
First Posted : August 9, 2005
Results First Posted : May 20, 2014
Last Update Posted : May 20, 2014
Information provided by (Responsible Party):
National Institutes of Health Clinical Center (CC) ( National Institute of Mental Health (NIMH) )

Brief Summary:

This study examines whether an antibiotic, d-cycloserine (DCS), boosts the effectiveness of cognitive behavior therapy (CBT) for social anxiety. CBT has been shown to be effective for the treatment of social anxiety in children and adults, but even after treatment, approximately 40% may remain diagnosable. The antibiotic DCS has been shown to enhance the type of learning that is promoted by exposure therapy, a main component of CBT. This study will test whether DCS can improve the effectiveness of CBT for social anxiety.

All participants will receive 12 weekly CBT sessions. In addition to receiving the CBT, participants will be randomly assigned (similar to a coin toss) to receive either DCS or a placebo (sugar pill). The pill will be taken 1-2 hours prior to each of the 12 CBT sessions. The pill is taken only on the 12 therapy days.

Prior to receiving treatment, participants will be asked to:

  • participate in interviews to assess diagnosis and how they are doing including mood, degree of nervousness and behavior
  • have a physical examination, a urine test, and an electrocardiogram (EKG)
  • undergo tests involving problem-solving and memory
  • prepare and present a speech to a "virtual audience" using virtual reality goggles
  • undergo functional magnetic resonance imaging (fMRI) while performing tasks that involve looking at pictures, remembering things, testing reaction times, and making simple choices

Those who have not improved by the end of the study will be offered standard antianxiety medication treatment for 1 to 3 months. If a participant does not wish to take medication, study clinicians will help him/her locate psychological care in the community. Participants will be asked to complete a follow-up assessment 3 months after their last CBT session.

Condition or disease Intervention/treatment Phase
Phobic Disorders Anxiety Social Phobia Drug: D-Cycloserine Drug: Placebo Phase 2

Detailed Description:

Social phobia afflicts between 3%-15% of the US population. As such, it is a particularly common debilitating psychiatric disorder. Like many anxiety disorders, social phobia typically arises during adolescence. Treatment has consisted of medication or cognitive behavioral therapy (CBT). Selective Serotonin Reuptake Inhibitors (SSRIs) represent the first-line pharmacological treatment both in adults as well as adolescents (APA Treatment Guidelines 2004). Similarly, CBT significantly improves outcome in both age groups. This treatment consists of psychoeducation, exposure therapy, and cognitive restructuring. While both treatments produce clinically meaningful benefits, most patients exhibiting positive responses to these treatments continue to exhibit marked residual symptoms, if not full-blown anxiety disorders. Thus, there is great need for treatment advances.

Intense fear of social scrutiny represents a core component of social phobia, and extinction of this fear represents the goal of exposure therapy during CBT (Cohn and Hope). Finding treatments that facilitate extinction is of paramount importance. In animals, extinction involves an active learning process that is blocked by glutamatergic NMDA antagonists and facilitated by NMDA agonists. Specifically, administration of D-cycloserine (DCS), a partial agonist at the glycine modulatory site on the NMDA receptor, produces a dose-dependent facilitation of extinction in the rat. As such, DCS might facilitate extinction during exposure-based CBT. Indeed, Ressler (Ressler et al 2004) recently reported preliminary data from a clinical trial supporting this hypothesis.

We will examine the degree to which DCS treatment can augment the clinical response in social phobia to CBT-exposure-based therapy. Specifically, we will study two groups of individuals with social phobia, both of whom will receive CBT. One group will receive placebo; a second group will receive 50 mg of D-cycloserine 1-2 hours before each exposure therapy session. We hypothesize that compared to placebo, DCS will produce greater reductions in social anxiety symptoms following CBT treatment. Finally, given that chronic social anxiety disorder virtually always begins during childhood, it is particularly vital to develop early interventions for the disorder. Accordingly, our trial will examine both adolescents and adults with the disorder.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 48 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: Effect of D-Cycloserine on Treatment of Social Phobia
Study Start Date : August 2005
Actual Primary Completion Date : June 2012
Actual Study Completion Date : August 2012

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Anxiety Phobias
Drug Information available for: Cycloserine

Arm Intervention/treatment
Active Comparator: D-Cycloserine
An antibiotic, d-cycloserine (DCS) was given to one group and the group is evaluated to see if the drug boosts the effectiveness of cognitive behavior therapy (CBT) for social anxiety.
Drug: D-Cycloserine
Placebo Comparator: Placebo
Another group was given the placebo and tested for effectiveness of cognitive behavior therapy (CBT) for social anxiety.
Drug: Placebo

Primary Outcome Measures :
  1. Clinical Global Improvement (CGI-S) Scale [ Time Frame: 12 weeks post baseline ]
    Symptom severity and improvement was assessed using the Clinical Global Impressions scale (CGI). It is a 2-item clinician-administered instrument that measures the patients' illness severity and global improvement. The minimum value for the CGI is 1=Normal, not at all ill and the maximum value is 7=Among the most extremely ill patients.

Secondary Outcome Measures :
  1. Liebowitz Social Anxiety Scale (LSAS) [ Time Frame: 12 weeks post baseline ]
    Social anxiety symptoms were assessed using the Liebowitz Social Anxiety Scale (LSAS). It is a 24-item self-report instrument that measures overall social anxiety fear and avoidance symptoms. This is the baseline assessment. The 24 items are each rated twice, from a "0" to "3" scale, with "0" indicated no level of symptom and "3" indicating a high level of the system. One rating is for anxiety, and the other is for avoidance. Thus, the lowest possible score is 0, and the highest possible score is 144. The total score represents the simple sum of all 48 ratings.

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.

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Ages Eligible for Study:   8 Years to 55 Years   (Child, Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

    1. Subjects between 8 yrs of age (preadolescents) and under 55 yrs of age.
    2. Subjects medically healthy.
    3. Able to give informed consent.
    4. Not on psychotropic meds for a minimum of 6 weeks for fluoxetine; a minimum of 1 week for PRN benzodiazepines and beta blockers, and a minimum of 3 weeks for all other psychotropic meds.
    5. Subjects diagnosed with DSM IV symptoms of social phobia, generalized or specific type.


  1. Current major depressive disorder.
  2. Lifetime diagnosis of psychotic disorder, bipolar disorder, eating disorder, mental retardation, substance or alcohol dependence (other than nicotine); active suicidal ideation.
  3. Current or lifetime history of a neurological disorder (other than tic disorders, febrile seizures of infancy), seizure disorder.
  4. Any unstable medical condition.
  5. Use of any psychoactive substance in the past 30 days.

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 identifier (NCT number): NCT00128401

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United States, Maryland
National Institutes of Health Clinical Center, 9000 Rockville Pike
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
National Institute of Mental Health (NIMH)
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Principal Investigator: Jennifer A Cameron, C.R.N.P. National Institute of Mental Health (NIMH)

Additional Information:
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Responsible Party: National Institute of Mental Health (NIMH) Identifier: NCT00128401    
Other Study ID Numbers: 050198
First Posted: August 9, 2005    Key Record Dates
Results First Posted: May 20, 2014
Last Update Posted: May 20, 2014
Last Verified: April 2014
Keywords provided by National Institutes of Health Clinical Center (CC) ( National Institute of Mental Health (NIMH) ):
Social Phobia
Additional relevant MeSH terms:
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Phobic Disorders
Phobia, Social
Anxiety Disorders
Mental Disorders
Anti-Bacterial Agents
Anti-Infective Agents
Anti-Infective Agents, Urinary
Renal Agents
Antibiotics, Antitubercular
Antitubercular Agents
Molecular Mechanisms of Pharmacological Action