How the drug D-cycloserine (DCS) can enhance Cognitive Behavioral Therapy

Exposure therapy is a well-known treatment for phobias and anxiety disorders, and recent research seeks to make exposure therapy even more effective through DCS, a drug that boosts learning in order to strengthen and speed up the effects of the therapy.

If you are familiar with Cognitive Behavioral Therapy (CBT) used to treat anxiety disorders, you might also be familiar with exposure therapy, a CBT technique that confronts the cause of anxiety in order to re-evaluate the actual danger present, and learn healthy ways to deal with the resulting fear. For example, if you are afraid of heights, exposure therapy might gradually expose you to different height levels, while teaching you better strategies to manage the stress it creates. Exposure therapy can be very effective – in a successful exposure, fear could begin with a high distress measurement of 80% to 90% and end significantly lower, at 10 to 20%. Ideally, this learning process should continue to lead patients to report a lowered distress rating whenever confronted by the feared object or event.

While effective, using exposure therapy to learn that a feared event or object is not dangerous takes time, as a patient will typically need to successfully confront the feared stimuli repeatedly to see lowered distress ratings. However, recent research has uncovered that there may be a way to speed up the benefits of exposure therapy, or even enhance the results.

This Drug Can Boost Learning and Reduce Anxiety Symptoms Faster

D-cycloserine (DCS), a memory enhancing drug that acts on specific nerve-cell receptors in the brain, can be used to improve the learning that takes place during exposure practices. DCS can help your cells respond to the neurotransmitter glutamate, which is important in a process integral to anxiety treatment called extinction learning. Extinction learning is the basis for exposure therapy: it allows anxious patients to learn that feared outcomes are unlikely to occur. After a patient with a phobia of spiders is exposed repeatedly to spiders without any negative consequences, the patient learns that the feared stimulus does not result in the feared outcome, and is able to overcome his or her fear.

The use of DCS can also lead to a faster reduction in anxiety symptoms over the course of treatment, and can even decrease the number of treatment sessions needed overall. The same holds true for symptoms of other anxiety-related problems, such as Social Anxiety Disorder, panic disorder, Obsessive-Compulsive Disorder, and Post-Traumatic Stress Disorder.

Because DCS is a memory enhancer and not an anxiolytic drug (a drug that reduces anxiety), taking DCS alone will not reduce anxiety. DCS only works to reduce anxiety symptoms in conjunction with exposure procedures, as it works to enhance the learning that takes place during therapy (i.e., by acting to boost the memory).

DCS Side Effects are Minimal, but Dose Timing Remains Uncertain

When used as a cognitive enhancer in conjunction with exposure therapy, doses of 50 and 250 milligrams of DCS are used, usually just for a few weeks. At this dose, DCS side effects are comparable to that of a placebo, with no known or recorded side effects.

However, scientists don’t yet fully understand the optimal dosing and dose timing (before or after fear subsides). As a recent study suggests, DCS’s effectiveness may depend on the success of the exposure itself. In other words, only patients who react with anxiety during the exposure therapy and then experience a significant decrease in anxiety by the end of the exposure may benefit from the medication. The study suggests that in an unsuccessful exposure (i.e., when the patient’s anxiety does not peak and then decrease), DCS may instead reinforce the anxious response.1

Next Steps in Using DCS to Enhance Exposure Therapy

Given that DCS has not yet been approved by the FDA as a drug used to enhance CBT for anxiety, it is currently unavailable to the public. However, a new research study examining DCS’s role in exposure therapy is being conducted at three universities: Boston University, University of Texas at Austin, and Rush University. The study will examine the effectiveness of giving DCS to patients only when fear subsides after an exposure.

If you feel anxious in social situations and live near one of the universities, please reach out to the appropriate contact for more information regarding possible participation in the clinical trial.

  • Boston University:
  • University of Texas at Austin:
  • Rush University:
Date of original publication: June 22, 2015
Updated on: February 10, 2016
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