3 - (SYM 68) Looking Back, Looking Ahead: Emotional Habituation as a Mechanism in Written Exposure for Anxiety

Negative imagery and memories are prevalent in anxiety disorders, but whether interventions should primarily target past experiences, or future threats remain under-explored. This randomized controlled trial (RCT) evaluates the efficacy and mechanisms of two transdiagnostic, self-administered online Written Exposure Therapy (WET) interventions: one emphasizing negative memory and the other imagined future threat. A diverse sample of Prolific participants with elevated pathological anxiety were randomly allocated to future-focused WET (n = 93), past-focused WET (n = 89), or an expressive writing control group (n = 89). The intervention involved four structured writing sessions with assessments at one week and three months post-intervention. At one-week follow-up, a significant group-by-session interaction emerged for subjective distress—reflecting emotional activation—in both experimental groups compared to controls (< ![if !msEquation] >< ![if !vml] >< ![endif] >< ![endif] >). Experimental groups exhibited greater initial activation and subsequent between-session habituation. Anxiety symptoms measured by the Overall Anxiety Severity and Impairment Scale significantly decreased over time in all groups (< ![if !msEquation] >< ![if !vml] >< ![endif] >< ![endif] >), though the magnitude did not differ between conditions (< ![if !msEquation] >< ![if !vml] >< ![endif] >< ![endif] >). Bayesian mediation analysis indicated that reductions in emotional activation mediated symptom improvements in future-focused WET (CI [-.16, -.05]) and past-focused WET (CI [-.21, -.08]), but not in the control group (CI [-.002, .08]), suggesting emotional habituation is central in WET, whereas targeting past versus future events produced comparable clinical improvements.