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Efficacy of pre-trauma prevention for post-traumatic stress disorder (PTSD) has not yet been established in a randomized controlled trial. Attention bias modification training (ABMT), a computerized intervention, is thought to mitigate stress-related symptoms by targeting disruptions in threat monitoring. We examined the efficacy of ABMT delivered before combat in mitigating risk for PTSD following combat.
We conducted a double-blind, four-arm randomized controlled trial of 719 infantry soldiers to compare the efficacy of eight sessions of ABMT (n = 179), four sessions of ABMT (n = 184), four sessions of attention control training (ACT; n = 180), or no-training control (n = 176). Outcome symptoms were measured at baseline, 6-month follow-up, 10 days following combat exposure, and 4 months following combat. Primary outcome was PTSD prevalence 4 months post-combat determined in a clinical interview using the Clinician-Administered PTSD Scale. Secondary outcomes were self-reported PTSD and depression symptoms, collected at all four assessments.
PTSD prevalence 4 months post-combat was 7.8% in the no-training control group, 6.7% with eight-session ABMT, 2.6% with four-session ABMT, and 5% with ACT. Four sessions of ABMT reduced risk for PTSD relative to the no-training condition (odds ratio 3.13, 95% confidence interval 1.01–9.22, p < 0.05, number needed to treat = 19.2). No other between-group differences were found. The results were consistent across a variety of analytic techniques and data imputation approaches.
Four sessions of ABMT, delivered prior to combat deployment, mitigated PTSD risk following combat exposure. Given its low cost and high scalability potential, and observed number needed to treat, research into larger-scale applications is warranted. The ClinicalTrials.gov identifier is NCT01723215.
Military training is a chronic stressful period that often induces stress-related psychopathology. Stress vulnerability and resilience depend on personality trait anxiety, attentional threat bias and prefrontal–limbic dysfunction. However, how these neurobehavioral elements interact with regard to the development of symptoms following stress remains unclear.
Fifty-five healthy combat soldiers undergoing intensive military training completed functional magnetic resonance imaging (fMRI) testing while performing the dot-probe task (DPT) composed of angry (threat) and neutral faces. Participants were then stratified according to their bias tendency to avoidance (n = 25) or vigilance (n = 30) groups, categorized as high or low trait anxiety and assessed for post-stress symptom severity.
Avoidance compared to vigilance tendency was associated with fewer post-trauma symptoms and increased hippocampal response to threat among high anxious but not low anxious individuals. Importantly, mediation analysis revealed that only among high anxious individuals did hippocampal activity lead to lower levels of symptoms through avoidance bias tendency. However, in the whole group, avoidance bias was modulated by the interplay between the hippocampus and the dorsal anterior cingulate cortex (dACC).
Our results provide a neurobehavioral model to explain the resilience to post-trauma symptoms following chronic exposure. The model points to the importance of considering threat bias tendency in addition to personality traits when investigating the brain response and symptoms of trauma. Such a multi-parametric approach that accounts for individual behavioral sensitivities may also improve brain-driven treatments of anxiety, possibly by targeting the interplay between the hippocampus and the dACC.
Post-traumatic stress disorder (PTSD) is a chronic and difficult to treat psychiatric disorder. Objective, performance-based diagnostic markers that uniquely index risk for PTSD above and beyond subjective self-report markers could inform attempts to improve prevention and early intervention. We evaluated the predictive value of threat-related attention bias measured immediately after a potentially traumatic event, as a risk marker for PTSD at a 3-month follow-up. We measured the predictive contribution of attentional threat bias above and beyond that of the more established marker of risk for PTSD, self-reported psychological dissociation.
Dissociation symptoms and threat-related attention bias were measured in 577 motor vehicle accident (MVA) survivors (mean age = 35.02 years, 356 males) within 24 h of admission to an emergency department (ED) of a large urban hospital. PTSD symptoms were assessed at a 3-month follow-up using the Clinician-Administered PTSD Scale (CAPS).
Self-reported dissociation symptoms significantly accounted for 16% of the variance in PTSD at follow-up, and attention bias toward threat significantly accounted for an additional 4% of the variance in PTSD.
Threat-related attention bias can be reliably measured in the context of a hospital ED and significantly predicts risk for later PTSD. Possible mechanisms underlying the association between threat bias following a potentially traumatic event and risk for PTSD are discussed. The potential application of an attention bias modification treatment (ABMT) tailored to reduce risk for PTSD is suggested.
Acute stress disorder involves prominent symptoms of threat avoidance. Preliminary cross-sectional data suggest that such threat-avoidance symptoms may also manifest cognitively, as attentional threat avoidance. Confirming these findings in a longitudinal study might provide insights on risk prediction and anxiety prevention in traumatic exposures.
Attention-threat bias and post-traumatic symptoms were assessed in soldiers at two points in time: early in basic training and 23 weeks later, during advanced combat training. Based on random assignment, the timing of the repeat assessment occurred in one of two schedules: for a combat simulation group, the repeat assessment occurred immediately following a battlefield simulation exercise, and for a control group, the assessment occurred shortly before this exercise.
Both groups showed no threat-related attention bias at initial assessments. Following acute stress, the combat simulation group exhibited a shift in attention away from threat whereas the control group showed no change in attention bias. Stronger threat avoidance in the combat simulation group correlated with severity of post-traumatic symptoms. Such an association was not found in the control group.
Acute stress may lead some individuals to shift their attention away from threats, perhaps to minimize stress exposure. This acute attention response may come at a psychological cost, given that it correlates with post-traumatic stress disorder (PTSD) symptoms. Further research is needed to determine how these associations relate to full-blown PTSD in soldier and civilian populations.