Heightened Biological Stress Response During Exposure to a Trauma Film Predicts an Increase in Intrusive Memories

Some people develop symptoms of posttraumatic stress disorder (PTSD) after having experienced a traumatic event, whereas others do not. Intrusive memories are a cardinal symptom of PTSD and a better understanding of encoding and consolidation of intrusive memory may yield important insights on differences in the response to trauma. The primary aim of this study is to investigate whether psychosocial stress induction (Trier Social Stress Test) versus active control (placebo version) leading to respective biological stress responses during the encoding and consolidation of a film-elicited analogue trauma influences the development of intrusive memories over the course of 7 consecutive days. We hypothesized that the activation of the biological stress system increases the number of intrusive memories over the course of 7 days. This single-blind randomized placebo-controlled study examined 122 young healthy women. Biological stress response was measured by salivary cortisol. salivary alpha-amylase activity, and heart rate variability. Generalized linear mixed models were used to analyze longitudinal effects of activation of biological stress response on self-reported number of intrusive memories. Cross-validated regularized regression (least absolute shrinkage and selection operator) was applied for data-driven feature selection including known biological and psychological predictors. Corroborating our hypothesis, biological stress-responders to the Trier Social Stress Test reported significantly more intrusive memories after trauma film. A priori designed post hoc tests point at significantly more intrusions on Day 1 and 2 in biological stress responders. Least absolute shrinkage and selection operator regression revealed salivary cortisol, salivary alpha-amylase activity, heart rate variability, subjectively rated distress, fear, and (on trend level) dissociation during the trauma film as relevant predictors of intrusive memories. A heightened biological stress response in young women is associated with more intrusive memories the first days after experiencing a trauma analogue.