The impact of torture on interpersonal threat and reward neurocircuitry

Abstract

Objective: Torture adversely influences emotional functioning, but the neurophysiological mechanisms underpinning its impact are unknown. This study examined how torture exposure affects the neural substrates of interpersonal threat and reward processing. Methods: Male refugees with (N = 31) and without (N = 27) torture exposure completed a clinical interview and functional magnetic resonance imaging scan where they viewed fear, happy and neutral faces. Between-group activations and neural coupling were examined as moderated by posttraumatic stress disorder symptom severity and cumulative trauma load. Results: Posttraumatic stress disorder symptom severity and trauma load significantly moderated group differences in brain activation and connectivity patterns. Torture survivors deactivated the ventral striatum during happy processing compared to non-torture survivor controls as a function of increased posttraumatic stress disorder symptom severity – particularly avoidance symptoms. The ventral striatum was more strongly coupled with the inferior frontal gyrus in torture survivors. Torture survivors also showed left hippocampal deactivation to both fear and happy faces, moderated by trauma load, compared to controls. Stronger coupling between the hippocampus and frontal, temporoparietal and subcortical regions during fear processing was observed, with pathways being predicted by avoidance and hyperarousal symptoms. Conclusion: Torture exposure was associated with distinct brain activity and connectivity patterns during threat and reward processing, dependent on trauma exposure and posttraumatic stress disorder symptom severity. Torture appears to affect emotional brain functioning, and findings have the potential to guide more targeted interventions for torture survivors.