Torture exposure and the functional brain: investigating disruptions to intrinsic network connectivity using resting state fMRI

Belinda J Liddell,Tim Outhred,Richard A Bryant,Jorge Aroche,Jessica Cheung,Gin S Malhi,Mariano Coello,Angela Nickerson,Kim L Felmingham,Miriam Den,Mirjana Askovic,Pritha Das

doi:10.1038/s41398-022-01795-3

Abstract

Torture has profound psychological and physiological consequences for survivors. While some brain structures and functions appear altered in torture survivors, it is unclear how torture exposure influences functional connectivity within and between core intrinsic brain networks. In this study, 37 torture survivors (TS) and 62 non-torture survivors (NTS) participated in a resting-state fMRI scan. Data-driven independent components analysis identified active intrinsic networks. Group differences in functional connectivity in the default mode network (DMN), salience network (SN) and central executive network (CEN) of the triple network model, as well any prefrontal network, were examined while controlling for PTSD symptoms and exposure to other potentially traumatic events. The analysis identified 25 networks; eight comprised our networks of interest. Within-network group differences were observed in the left CEN (lCEN), where the TS group showed less spectral power in the low-frequency band. Differential internetwork dynamic connectivity patterns were observed, where the TS group showed stronger positive coupling between the lCEN and anterior dorsomedial and ventromedial DMN, and stronger negative coupling between a lateral frontal network and the lCEN and anterior dorsomedial DMN (when contrasted with the NTS group). Group differences were not attributed to torture severity or dissociative symptoms. Torture survivors showed disrupted dynamic functional connectivity between a laterally-aligned lCEN that serves top-down control functions over external processes and the midline DMN that underpins internal self-referential processes, which may be an adaptive response to mitigate the worst effects of the torture experience. This study provides a critical step in mapping the neural signature of torture exposure to guide treatment development and selection.

Highlights

Torture, according to the United Nations Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment (UNCAT), is defined as an intentional act of physical or psychological harm inflicted on a person for the purposes of obtaining information, punishment, intimidation and/or discrimination of any kind by a person in or acting for a person in an official capacity [1]
MRI data acquisition MRI scanning was completed within 1–2 weeks following the clinical interview, using a 3T Siemens Magnetom Trio Scanner based at the Advanced Research and Clinical High-field Imaging (ARCHI) facility in Sydney
This study investigated the effect of exposure to torture on functional brain networks and found differential intrinsic network connectivity in a group of torture survivors (TS) compared to nontorture survivors (NTS)

Summary

Introduction

Torture, according to the United Nations Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment (UNCAT), is defined as an intentional act of physical or psychological harm inflicted on a person for the purposes of obtaining information, punishment, intimidation and/or discrimination of any kind by a person in or acting for a person in an official capacity [1]. It is most commonly characterised by exposure to interpersonally harmful events delivered in captivity with the purpose of evoking a complete loss of control [2]. Understanding how torture identifying core mechanisms that could be new treatment targets affects the dynamic connectivity of these key functional networks for survivors [19]

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