The tuberculosis drug, D-Cycloserine, increases the benefits of exposure therapy for social anxiety disorder, researchers have found. Pilot data shows that short-term use of the drug decreases social anxiety symptoms significantly, according to the study published in the March 2006 Archives of General Psychiatry.
D-Cycloserine (DCS) is an antibiotic approved by the U.S. Food and Drug Administration (FDA) to treat tuberculosis. It already has been shown to have positive effects in the treatment of Alzheimer's disease, schizophrenia, and acrophobia (the fear of heights).
In animal and some human studies, DCS has been shown to help learning. Researchers believe that fear learning and extinction is blocked by brain chemicals at a brain receptor known as glutamatergic N-methyl-D-aspartate (NMDA). The NMDA receptor plays an important role in learning and memory. Animal and human studies have shown that D-Cycloserine assists brain chemicals at the NMDA receptor. More importantly, DCS appears to help decrease conditioned fear, particularly if used prior to exposure to the feared situation or object.
Although treatment strategies for social anxiety disorders have improved, the success rate still is rather low. Researchers from the Center for Anxiety and Related Disorders at Boston University decided to examine the effects of DCS combined with short-term exposure therapy for social anxiety disorder, particularly public speaking. At three different clinics, a total of 27 patients received five sessions of exposure therapy for public speaking combined either with DCS or a placebo.
Patients receiving DCS reported significantly less social anxiety symptoms than the patients using the placebo. Over time, the difference in number of symptoms between the two groups increased linearly. This includes a one-month follow-up after the exposure sessions had ended. Additionally, patients taking DCS reported less social anxiety symptoms overall (not just those related to public speaking).
"The results of this study offer encouraging preliminary support for the select use of DCS to help people with social anxieties learn more from therapy and achieve strong gains through relatively limited treatment," said Dr. Michael Otto, one of the researchers, in a Boston University press release. A low dose of DCS was used in the study, administered one hour before exposure sessions. This short-term use of DCS had a low rate of adverse effects on patients.
"Studies like this may usher in a new strategy for combining medications and cognitive-behavior therapy," said Dr. Otto. "Instead of simply combining medications and therapy that are each designed to reduce anxiety and avoidance, the use of DCS is directed toward making the therapeutic learning in cognitive-behavior therapy stronger. Medication use is limited to only a few doses, taken before therapy sessions."
Researchers hope larger studies will confirm their findings. The short-term use of DCS with exposure therapy may provide much-needed relief to the many people with social anxiety disorder and possibly with other types of anxiety disorders.
References:
1) Hofmann SG, Meuret AE, Smits JAJ, Simon NM, Pollack MH, Eisenmenger K, Shiekh M, Otto MW (2006). Augmentation of exposure therapy with D-Cycloserine for social anxiety disorder. Arch Gen Psychiatry 63: 298-304.
2) Edler K (2006). Study shows antibiotic boosts benefits of therapy for social anxiety disorder. Boston University press release.