5 - (SYM 4) Validating the Human Extinction Workgroup Protocol for Extinction Enhancement Research and Implications for Translational Exposure Therapy Research

Fear conditioning is a long-standing translational tool used to help understand the development and treatment of fear-related disorders, with the extinction phase being considered an analog for exposure and tests of return of fear an analog for relapse. This has led to an abundance of research on predictors of extinction and return of fear, as well as studies on strategies to enhance extinction in the lab, with the goal of translation to the clinic to enhance exposure therapy. Despite this, there is no standardized fear conditioning protocol that is optimized for extinction enhancement research. The goal of the current study was to validate such a protocol.

The protocol was designed with input from the fear conditioning research community. Adults (n=127) completed habituation, acquisition, and extinction procedures on day 1 and a test of return of fear (i.e., spontaneous recovery) on day 2. Skin conductance responses (SCRs) and shock expectancy ratings were collected as indicators of fear response. All participants completed the Depression Anxiety Stress Scale-21 (DASS-21) and some additionally completed the Intolerance of Uncertainty Scale (IUS; n=43). Data were collected across 3 sites: Tufts University (n=57), University of Texas at Austin (n=49), and KU Leuven (n=21). Linear mixed effects regression modeling was conducted.

Across all sites, participants (M(SD) age=22.0(6.3); 67% female; 35% Asian, 22% White, 43% Other) demonstrated significantly greater SCRs to the threat cues than safety cues during acquisition (β=0.33, p< 0.001). This effect diminished by the last quarter of extinction (β=0.06, p=0.17), and robust return of fear was observed at the start of test (β=0.21, p< 0.001). Results were similar for shock expectancy ratings. Between site reliability statistics will be presented. Consistent with past research, higher IUS scores predicted greater return of fear as assessed by SCR at test, even when controlling for DASS-21 anxiety scores (β=0.14, p< 0.05).

These data suggest that the Human Extinction Workgroup protocol results in adequate fear acquisition and extinction, and robust return of fear. We also observed expected associations with psychological symptoms. If reliability across sites is strong, the protocol could be a useful tool for studies examining extinction enhancement. This protocol has the potential to reduce barriers to studying fear extinction and extinction enhancement strategies in clinical populations, an important step in the translational research process for improving exposure therapy outcomes.