Measuring fear change within exposures: Functionally-defined habituation predicts outcome in three randomized controlled trials for pediatric OCD

Abstract

Objective: This study measured a variety of within-exposure fear changes and tested the relationship of each with treatment outcomes in exposure therapy.

Method: We coded 459 videotaped exposure tasks from 111 participants in 3 clinical trials for pediatric obsessive-compulsive disorder (OCD; POTS trials). Within exposures, fear level was observed continuously and alongside exposure process. Fear change metrics of interest were selected for relevance to mechanistic theory. Fear decreases were classified by function; nonhabituation decreases were associated with observed nonlearning processes (e.g., avoidance), whereas habituation decreases appeared to result from an internal and indirect process. Outcomes were posttreatment change in symptom severity, global improvement, and treatment response.

Results: Greater cumulative habituation across treatment was associated with larger reductions in symptom severity, greater global improvement, and increased odds of treatment response. Fear activation, fear variability, and nonhabituation fear decreases did not predict any outcomes. Exploratory analyses examined fear changes during habituation and nonhabituation exposures; higher peak fear during nonhabituation exposures was associated with attenuated global improvement.

Conclusions: Habituation is conceptually consistent with multiple mechanistic theories and should continue to be investigated as a practical marker of initial extinction learning and possible moderator of the relationship between fear activation and outcome. Results support the importance of functional and frequent fear measurement during exposures, and discussion considers implications of these findings for future studies aiming to understand learning during exposure and improve exposure delivery. (PsycINFO Database Record

Figure 1. Example exposure: Fear trajectory

Example Exposure. The chosen exposure task is to stand approximately two feet away from the family dog. As the exposure begins, the patient approaches the contaminated dog with initial observed fear of 4/5. After several minutes, the dog walks away from the patient (attempting to sniff around the office), the patient’s perception of immediate risk lessens, and fear decreases accordingly to 2/5. The therapist shortens the leash and the dog moves closer, with fear increase to 3/5. The patient then has a new contamination thought, becoming concerned that the leash may have brushed his arm inadvertently— and fear increases to 4/5. The patient remains engaged in the exposure even with this thought, and fear eventually decreases on its own to 1/5. The patient then agrees to move closer to the dog by about one foot, and fear increases again to 4/5. Over the next few minutes, fear decreases to 3/5, and then they run out of time in the session. The patient leaves with instructions to resist cleaning his arm or any other contaminated areas for the remainder of the day

Figure 2

Example exposure: Fear change metrics

Figure 3

Eligibility Criteria and Included Participants

Figure 4

Change in Symptom Severity as a function of Habituation and Non-Habituation Fear Decreases

Figure 5. Change in Symptom Severity as a function of Fear Change Metrics

^aParticipants with zero observed scores were modeled separately for metrics based on counts (Fear increases, sum of all fear changes, exposures ending in zero fear) but not for metrics where zero values were observed (peak fear, peak-end fear). One participant had zero fear changes and was removed from that analysis for model convergence