Fear activation and habituation patterns as early process predictors of response to prolonged exposure treatment in PTSD.

Improved (n = 21) and nonimproved (n = 13) PTSD patients (a mixed trauma population) were compared for fear activation and habituation patterns during and between the 1st and 2nd prolonged exposure sessions. Drop-outs (n = 11) were also evaluated. Nonimproved patients had significantly higher ratings of anxiety at the start of the first exposure session. Improved patients showed more within-session habituation during the self-exposures at home and more between-session habituation. Even after controlling for initial PTSD and depression symptom severity, habituation between the first and second exposure sessions was significantly related to treatment outcome. Patients who dropped out of the treatment were found not to differ from completers on fear activation and within-session habituation during the first exposure session.