Amygdala activity during human freezing prospectively predicts trajectories of PTSD development in Dutch police officers

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Objective: People working in risk professions are repeatedly exposed to potential traumatic events (PTEs) making them more vulnerable for development of psychopathology such as posttraumatic stress disorder (PTSD). Even though the majority seem to be resilient to stressor exposure, a small group seem to be at higher risk for development of stress symptoms. Looking at symptom development over a longer time period enables to identify different trajectories. Investigating which neural- and physiological baseline measurements predict this higher vulnerability allows for applying early interventions to improve resilience aiming to prevent development of full-blown PTSD. Methods: Within a cohort of 140 Dutch police recruits, four measurements were collected over a period of six years including a baseline measurement before trauma exposure. Stress symptom trajectories were identified using a nonparametric k-means cluster analysis for longitudinal data (KmL). Baseline dentate gyrus (DG) volume, anterior prefrontal cortex (aPFC) activity, amygdala activity during freezing and local salience network (SN) connectivity changes were included as neural predictors. Somatic predictors included hair cortisol, salivary cortisol and heart rate variability (HRV) measurements at baseline. Multiple logistic regression models were used to investigate the predictive effect of baseline neural- and physiological measurements on the cluster distribution. Results: Two distinct stress symptom trajectories were identified. First a resilient group showing relatively low symptom development over time and secondly an increased symptom group with significant higher symptom scores over all timepoints and a temporal increase right after trauma exposure. Baseline amygdala activity during freezing was able to predict the cluster distribution (ß = 7.455; p = 0.025) above and beyond other somatic predictors. Conclusions: Increased amygdala activity during defensive responses before trauma exposure may serve as a predisposing vulnerability factor for trauma-related trajectories. Early interventions focussing on reducing this amygdala activity may improve resilience in police officers preventing development of PTSD symptoms.
Faculteit der Sociale Wetenschappen