D-cycloserine enhancement of fear extinction is specific to successful exposure
sessions: evidence from the treatment of height phobia.
Author(s): Smits JA(1), Rosenfield D, Otto MW, Powers MB, Hofmann SG, Telch MJ, Pollack MH,
Tart CD.
Affiliation(s): Author information:
(1)Department of Psychology, Southern Methodist University, Dallas, Texas 75206,
USA. jsmits@smu.edu
Publication date & source: 2013, Biol Psychiatry. , 73(11):1054-8
BACKGROUND: Whereas some studies have shown clear evidence for an augmentation
effect of D-cycloserine (DCS) on exposure therapy for anxiety disorders, other
studies have shown weak effects or no effect at all. Some preclinical data
suggest that the DCS augmentation effect is moderated by the success of
extinction learning. Therefore, we conducted a reanalysis of existing data to
examine whether the effects of DCS on clinical outcome would vary as a function
of response to the exposure session (i.e., exposure success).
METHODS: In a clinical trial, patients with height phobia received two sessions
involving 30 minutes of virtual reality exposure therapy and were randomly
assigned to a pill placebo (n = 14) or 50 mg of DCS (n = 15) immediately after
each session.
RESULTS: Mixed-effects regression analysis showed that the effects of DCS
administration on clinical improvement was moderated by the level of fear
experienced just before concluding exposure sessions. Patients receiving DCS
exhibited significantly greater improvement in symptoms relative to patients who
received placebo when fear was low at the end of the exposure. In contrast, when
end fear was still elevated, patients receiving DCS improved less compared with
those receiving placebo.
CONCLUSIONS: D-cycloserine appears to enhance the benefits of exposure treatment
when applied after a successful session, but it seems to have detrimental effects
when administered after inadequate/unsuccessful exposure sessions.
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