(PS14-51) The Relationship Between Proficiency in Suppression Induced Forgetting and Trauma Based Intrusions

Post Traumatic Stress Disorder (PTSD) is a heterogeneous disorder characterized by intrusive trauma-based cognitions. Past studies indicate individuals with PTSD often experience difficulties in response inhibition (RI), which can lead to problems with regulating emotions and behavior (e.g., Dillon & Pizzagalli, 2007). Although various studies have shown PTSD-related behavioral RI deficits, fewer studies explore cognitively driven mechanisms of inhibition such as suppression induced forgetting (SIF). SIF involves intentionally suppressing the retrieval of unwanted memories. Heightened PTSD severity and increased intrusions may result from an inability to inhibit automatic thoughts triggered by trauma-based cues and, in turn, may strengthen associative memory between cues and threats. Thus we hypothesized that individuals with higher PTSD symptom severity would show impairments in SIF.  

Data was gathered from 28 midwestern university students. To assess SIF, we employed the Think/No-Think (TNT) task, consisting of three phases. 1. In the learning phase, participants encoded cue and target word pairs (e.g., cat-dog). Subsequently, cues were presented to confirm encoding. 2. During the suppression training phase, participants were instructed to suppress specific target word recall (no-think) while recalling others (think). 3. In the final recall phase, participants recalled cued target words regardless of prior instructions. SIF was quantified by calculating the ratio of successfully recalled no-think targets to think targets (suppression/recall). We used the Depression Anxiety and Stress Scale 21 (DASS-21) and the PTSD Checklist for DSM-5 (PCL-5) to gauge depression and PTSD symptoms. We utilized the depression subscale on the DASS-21 and each PCL-5 subscale including re-experiencing, avoidance, negative alterations in cognition and mood, and hyperarousal. 

To analyze whether PTSD or mood-based symptoms would predict SIF deficits we entered each PCL-5 subscale and DASS-21 depression score into a hierarchical linear regression with SIF as the dependent variable. The overall regression model was statistically significant (R2 = .378, F(5,22)=2.76, p = .049) and re-experiencing (β=.-.08, p </span>< .02) was shown to be a significant predictor of SIF. Additionally, PTSD-related avoidance was shown to be trending towards significance (β=.115, p </span>=.07). Depressive symptoms, negative alterations in cognition/mood, and hyperarousal were not shown to significantly predict SIF (p >.664).  

Individuals with PTSD often experience distress due to trauma-based intrusions. Contrary to our hypothesis, those with heightened intrusions showed superior abilities in forgetting previously learned information through thought suppression. Individuals with frequent intrusions may use suppression as a maladaptive coping mechanism for temporary symptom reduction. However, as shown in previous studies (e.g., Beck et al., 2009) a rebound of intrusive thoughts may occur. Our study which utilized neutral word pairs may have contributed to reduced difficulties in thought suppression. Future research should explore differences between trauma-specific, emotionally, and neutrally valenced word pairs.