Abstract
Post-traumatic stress disorder (PTSD) is a mental health injury characterised by re-experiencing, avoidance, numbing and hyperarousal. Whilst the aetiology of the disorder is relatively well understood, there is debate about the prevalence of cognitive sequelae that manifest in PTSD. In particular, there are conflicting reports about deficits in executive function and mental flexibility. Even less is known about the neural changes that underlie such deficits. Here, we used magnetoencephalography to study differences in functional connectivity during a mental flexibility task in combat-related PTSD (all males, mean age = 37.4, n = 18) versus a military control (all males, mean age = 33.05, n = 19) group. We observed large-scale increases in theta connectivity in the PTSD group compared to controls. The PTSD group performance was compromised in the more attentionally-demanding task and this was characterised by 'late-stage' theta hyperconnectivity, concentrated in network connections involving right parietal cortex. Furthermore, we observed significant correlations with the connectivity strength in this region with a number of cognitive-behavioural outcomes, including measures of attention, depression and anxiety. These findings suggest atypical coordination of neural synchronisation in large scale networks contributes to deficits in mental flexibility for PTSD populations in timed, attentionally-demanding tasks, and this propensity toward network hyperconnectivity may play a more general role in the cognitive sequelae evident in this disorder.
Highlights
Post-traumatic stress disorder (PTSD) is a serious mental health injury described by anxious and depressive features which develop after exposure to a traumatic life event(s)
Georgopoulos et al [31] demonstrated that atypical patterns of abnormal synchronous oscillations are able to differentiate PTSD from control subjects, and that ineffective communication between right temporo-parietal areas and other brain regions might underlie aspects of the disorder [32]. This group reported negative correlations between neural oscillations in the right superior temporal gyrus, with resilience to lifetime trauma in control veterans, but not those with PTSD [33], and recently, we have shown that high-frequency gamma synchronisation (80–150 Hz) differentiates PTSD from control soldiers, with network strength measures in the left hippocampus correlating with symptom severity [34]
Measures of reaction time and task accuracy were separately submitted to a 2x2 mixed factorial ANOVA with ‘Group’ (PTSD and control) as the between-participant variable and ‘Condition’ (Intra- and Extra-dimensional) as the within-participant variable
Summary
Post-traumatic stress disorder (PTSD) is a serious mental health injury described by anxious and depressive features which develop after exposure to a traumatic life event(s). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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