D-cycloserine enhancement of exposure therapy for social anxiety disorder depends
on the success of exposure sessions.
Author(s): Smits JA(1), Rosenfield D, Otto MW, Marques L, Davis ML, Meuret AE, Simon NM,
Pollack MH, Hofmann SG.
Affiliation(s): Author information:
(1)Department of Psychology, Southern Methodist University, USA. jsmits@smu.edu
Publication date & source: 2013, J Psychiatr Res. , 47(10):1455-61
OBJECTIVE: The evidence for the efficacy of D-cycloserine (DCS) for augmenting
cognitive behavioral therapy (CBT) for anxiety disorders has been mixed. Guided
by preclinical research and initial findings from a small-scale study involving
humans, we tested the hypothesis that DCS enhancement of exposure therapy would
be specific to successful exposure sessions.
METHOD: Medication-free adults with generalized social anxiety disorder (N = 145)
received 50 mg of DCS or placebo 1 h before each of 5 exposure sessions that were
part of a standardized 12-session group CBT protocol. Participants provided fear
ratings at the beginning and just before the end of exposure exercises.
Independent raters, blind to group assignment, administered the clinical global
impression improvement and severity scales at each session and at posttreatment.
RESULTS: Mixed-effects analyses revealed that, among patients who reported low
fear at the end of an exposure session, those who had received DCS evidenced
significantly greater clinical improvement at the next session, relative to those
who had received placebo. In contrast, when exposure end fear was high, patients
receiving DCS exhibited less clinical improvement at the following session than
patients receiving placebo. Similarly, patients who had received DCS evidenced
lower clinical severity at posttreatment, relative to patients who had received
placebo, only when their average end fear for medication-augmented sessions had
been in the low to moderate range. Finally, these moderating effects of exposure
success as indexed by end fear were not better accounted for by within-session
extinction.
CONCLUSIONS: The efficacy of DCS for augmenting exposure-based CBT depends on the
success of exposure sessions. These findings may help guide the development of an
algorithm for the effective use of DCS for augmenting exposure-based CBT.
TRIAL REGISTRY: http://www.ClinicalTrials.gov, ID# NCT00633984,
http://www.clinicaltrials.gov/ct2/show/NCT00633984.
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