Cycloserine Speeds Therapy Effects in OCD

There is considerable interest in methods to speed up the effects of treatments for obsessive-compulsive disorder (OCD).  Exposure and response prevention are key therapy interventions for OCD and these treatments have significant evidence-based support for effectiveness.  A recent study examined whether the drug d-cycloserine can boost the effect of standard behavior therapy in OCD.

D-cycloserine (DCS) is an antibiotic that appears to have cognitive effects that "facilitates fear extinction and enhances associative learning by acting as a partial agonist at N-methyl-D-aspartate receptors in the brain."  These effects have been demonstrated in animal models as well as in humans with specific phobias and social anxiety disorder. 

Chasson and colleagues from Harvard Medical School, Humboldt University in Berlin and Yale conducted a randomized clinical trial of DCS versus placebo in a group of subjects with OCD receiving exposure therapy and response prevention (ERP) for OCD.

The key elements of the design of the study included:

• 29 subjects were randomized for the study and 7 dropped out early in treatment
• 10 subjects received DCS and 12 placebo
• ERP consisted of twice-weekly one hour sessions
• One hour before therapy subjects received 100 mg of DCS or placebo
• Subjects and investigators were blind to drug or placebo assignment
• The Yale-Brown obsessive compulsive scale-self report was used as the primary outcome measures

Key findings from the study included:

• The DCS group improved more rapidly, particularly in the first 5 weeks
• The placebo group showed essentially no response in the first 5 weeks
• DCS did not appear to be more effective over the 10 week course of treatment

So the main take home message from this study is that DCS appears to have the potential to speed up the effect of behavior therapy in OCD.  This effect will need to be replicated in larger samples.  The increased speed of onset of a therapeutic effects could have important advantages.  These might include the using a shorter duration of treatment and reducing drop out rates.  Patients who improve rapidly tend to have better treatment adherence and stay in treatment longer.  However, this effect was not seen in the Chasson et al sample as four subjects dropped out in the DCS group compared to three in the placebo group.

The study did not extensively comment on the tolerability of DCS in the study sample.  DCS can produce headaches, irritability and seizures.   The side effects would be limited by only using the drug during a course of behavior therapy.  Nevertheless, using DCS would require physician assessment and monitoring during the course of therapy.

Photo of a pair of black swans from Red Berry mansion courtesy of Yates Photography.

Chasson GS, Buhlmann U, Tolin DF, Rao SR, Reese HE, Rowley T, Welsh KS, & Wilhelm S (2010). Need for speed: evaluating slopes of OCD recovery in behavior therapy enhanced with d-cycloserine. Behaviour research and therapy, 48 (7), 675-9 PMID: 20362975