A randomized controlled trial comparing two processes of exposure therapy: Extinction learning and habituation

To investigate the role of extinction learning and habituation by comparing inhibitory retrieval to habituation-focused exposure for social anxiety and panic disorder.

In this assessor-blinded, parallel-group, two-arm randomized controlled clinical superiority trial, 89 treatment-seeking adults with social anxiety (n = 77) or panic disorder (n = 12) received nine weekly therapy sessions of inhibitory retrieval or habituation-focused exposure therapy. Outcomes were client-reported symptoms, interviewer-rated client distress and impairment, and a behavioral approach task.

Modified intent-to-treat analyses were conducted using multilevel modeling. There were no group differences on principal outcomes of interviewer-rated distress and impairment, nor significant pairwise differences on symptom scores at posttreatment or follow-up (ps > .11). However, secondary and exploratory analyses revealed that relative to the habituation condition, participants in the inhibitory retrieval condition demonstrated significantly steeper decreases in self-reported anxiety from baseline to posttreatment, b = 0.05, 95% CI [0.01, 0.08], χ2(1) = 6.67, p = .010; session-by-session self-reported anxiety, b = 0.01, 95% CI [0.004, 0.02], χ2(1) = 12.33, p = .001; and distress during a behavioral approach task, f = .134, χ2(1) = 4.75, p = .029. Additionally, a higher percentage of participants in the inhibitory condition achieved clinically significant change on self-reported anxiety at posttreatment (43% vs. 13%), although there were no group differences on interviewer-rated indices of clinically significant change (ps > .42).

Both methods of exposure therapy were effective. Exposure therapy targeting extinction learning modestly improved outcomes on secondary and exploratory measures although, aside from reliable and clinically significant change, group differences at posttreatment and follow-up were not significant. Habituation-focused exposure therapy was not superior on any measure. (PsycInfo Database Record (c) 2025 APA, all rights reserved).