25970252
OBJECTIVE	It is unclear whether d-cycloserine ( DCS ) , a partial N-methyl-d-aspartate agonist that enhances fear extinction , can augment the effects of exposure-based cognitive behavioral therapy ( CBT ) for obsessive-compulsive disorder ( OCD ) .
OBJECTIVE	To examine whether DCS augments the effects of CBT for OCD and to explore ( post hoc ) whether concomitant antidepressant medication moderates the effects of DCS .
METHODS	A 12-week , double-blind randomized clinical trial with 3-month follow-up conducted at an academic medical center between September 4 , 2012 , and September 26 , 2013 .
METHODS	Participants included 128 adult outpatients with a primary diagnosis of OCD and a Yale-Brown Obsessive Compulsive Scale ( Y-BOCS ) score of 16 or higher .
METHODS	Concurrent antidepressant medication was permitted if the dose had been stable for at least 2 months prior to enrollment and remained unchanged during the trial .
METHODS	The main analysis was by intention-to-treat population .
METHODS	All participants received a previously validated Internet-based CBT protocol over 12 weeks and were randomized to receive either 50 mg of DCS or placebo , administered 1 hour before each of 5 exposure and response prevention tasks .
METHODS	Clinician-administered Y-BOCS score at week 12 and at 3-month follow-up .
METHODS	Remission was defined as a score of 12 or lower on the Y-BOCS .
RESULTS	In the primary intention-to-treat analyses , DCS did not augment the effects of CBT compared with placebo ( mean [ SD ] clinician-rated Y-BOCS score , DCS : 13.86 [ 6.50 ] at week 12 and 12.35 [ 7.75 ] at 3-month follow-up ; placebo : 11.77 [ 5.95 ] at week 12 and 12.37 [ 6.68 ] at 3-month follow-up ) but showed a significant interaction with antidepressants ( clinician-rated Y-BOCS , B = -1.08 ; Z = -2.79 ; P = .005 ) .
RESULTS	Post hoc analyses revealed that antidepressants significantly impaired treatment response in the DCS group but not the placebo group , at both posttreatment and follow-up ( clinician-rated Y-BOCS : t62 = -3.00 ; P = .004 ; and t61 = -3.49 ; P < .001 , respectively ) .
RESULTS	In the DCS group , a significantly greater proportion of antidepressant-free patients achieved remission status at follow-up ( 60 % [ 95 % CI , 45 % -74 % ] ) than antidepressant-medicated patients ( 24 % [ 95 % CI , 9 % -48 % ] ) ( P = .008 ) .
RESULTS	Antidepressants had no effect in the placebo group ( 50 % [ 95 % CI , 36 % -64 % ] remission rate in both groups ) .
CONCLUSIONS	The findings suggest that antidepressants may interact with DCS to block its facilitating effect on fear extinction .
CONCLUSIONS	Use of DCS may be a promising CBT augmentation strategy but only in antidepressant-free patients with OCD .
BACKGROUND	clinicaltrials.gov Identifier : NCT01649895 .

