Resting-state hippocampal connectivity correlates with symptom severity in post-traumatic stress disorder

Abstract

Post-traumatic stress disorder (PTSD) is a serious mental health injury which can manifest after experiencing a traumatic life event. The disorder is characterized by symptoms of re-experiencing, avoidance, emotional numbing and hyper-arousal. Whilst its aetiology and resultant symptomology are better understood, relatively little is known about the underlying cortical pathophysiology, and in particular whether changes in functional connectivity may be linked to the disorder. Here, we used non-invasive neuroimaging with magnetoencephalography to examine functional connectivity in a resting-state protocol in the combat-related PTSD group ( n = 23), and a military control group ( n = 21). We identify atypical long-range hyperconnectivity in the high-gamma-band resting-state networks in a combat-related PTSD population compared to soldiers who underwent comparable environmental exposure but did not develop PTSD. Using graph analysis, we demonstrate that apparent network connectivity of relevant brain regions is associated with cognitive-behavioural outcomes. We also show that left hippocampal connectivity in the PTSD group correlates with scores on the well-established PTSD Checklist (PCL). These findings indicate that atypical synchronous neural interactions may underlie the psychological symptoms of PTSD, whilst also having utility as a potential biomarker to aid in the diagnosis and monitoring of the disorder.

Graphical abstract

Highlights

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  Soldiers with PTSD display increased connectivity in high gamma resting state.

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  Left frontal, temporal and hippocampus regions show hyperconnectivity in PTSD.

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  Emotionally-salient stimuli induced increased connectivity in soldiers without PTSD.

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  Connectivity strength in left hippocampus correlates with PTSD symptom severity.