Hyperarousal symptoms and decreased right hemispheric frontolimbic white matter integrity predict poorer sleep quality in combat-exposed veterans

Abstract

Objective: Disrupted sleep is common following combat deployment. Contributors to risk include posttraumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI); however, the mechanisms linking PTSD, mTBI, and sleep are unclear. Both PTSD and mTBI affect frontolimbic white matter tracts, such as the uncinate fasciculus. The current study examined the relationship between PTSD symptom presentation, lateralized uncinate fasciculus integrity, and sleep quality. Method: Participants include 42 combat veterans with and without PTSD and mTBI. Freesurfer and Tracula were used to establish specific white matter ROI integrity via 3-T MRI. The Pittsburgh Sleep Quality Index and PTSD Checklist were used to assess sleep quality and PTSD symptoms. Results: Decreased fractional anisotropy in the right uncinate fasciculus (β = −1.11, SE = 0.47, p < .05) and increased hyperarousal symptom severity (β = 3.50, SE = 0.86, p < .001) were associated with poorer sleep quality. Conclusion: Both right uncinate integrity and hyperarousal symptom severity are associated withsleep quality in combat veterans. The right uncinate is a key regulator of limbic behavior and sympathetic nervous system reactivity, a core component of hyperarousal. Damage to this pathway may be one mechanism by which mTBI and/or PTSD could create vulnerability for sleep problems following combat deployment.

A conceptual framework for a neurophysiological basis of art therapy for PTSD

“…Causality is unclear. Further, white matter structures connecting these regions also show differences in people with PTSD and anxiety disorders, with reductions in white matter integrity demonstrated in the uncinate fasciculus, a key fronto-limbic pathway ( Costanzo et al, 2016 ; Tromp et al, 2019 ), which also appears to be associated with greater expression of sleep problems in patients with PTSD and mild TBI ( Bottari et al, 2021 ). While reductions in white matter integrity may reflect damage, increases in structural quality measured with DTI have been shown to relate to the learning of new skills.…”

“…Active-duty military members and Veterans are at elevated risk for exposure to traumatic events ( Kilpatrick et al, 2013 ) and TBI, which is a risk factor for prolonged recovery from PTSD ( Vanderploeg et al, 2009 ; Otis et al, 2011 ; Lange et al, 2020 ). The mechanistic link between TBI and PTSD is unclear, though it may potentially relate to changes in white matter structures important in regulating emotion and therefore, TBI may result in symptom exacerbation ( Williamson et al, 2013 ; Bottari et al, 2021 ). Damage to white matter preferentially affects function of frontally connected networks ( Sharp et al, 2014 ; Hayes et al, 2016 ; Filley and Kelly, 2018 ) important in emotional regulation, processing speed, attention, and executive functions.…”

Posttraumatic Stress Disorder and Anxiety-Related Conditions

“…Reduced fractional anisotropy of the uncinate fasciculus, a frontal limbic white matter tract, is associated with startle and subthreshold PTSD symptoms in recently deployed military service members 72 . Mild TBI, a common occurrence in military personnel diagnosed with PTSD (elevated rates of PTSD subsequent to mild TBI), may impact this circuit and potentially contribute to the manifestation of symptoms of PTSD, although causality is unclear because of a lack of longitudinal studies 6,73 …”

“…72 Mild TBI, a common occurrence in military personnel diagnosed with PTSD (elevated rates of PTSD subsequent to mild TBI), may impact this circuit and potentially contribute to the manifestation of symptoms of PTSD, although causality is unclear because of a lack of longitudinal studies. 6,73 In addition to differences in activity of fear circuitry, structural differences are also evident in anxiety-related disorders, even in children. Specifically, uncinate fasciculus fractional anisotropy is lower in boys with anxiety disorders.…”

Sleep Quality Disturbances Are Associated with White Matter Alterations in Veterans with Post-Traumatic Stress Disorder and Mild Traumatic Brain Injury

“…Most studies utilized fractional anisotropy (FA) as a marker of white matter microstructural integrity and tissue organization and found lower FA related to poorer sleep quality in frontal, temporal, parietal, and occipital regions [55][56][57][58][59][60][61][62][63][64][65]. A few studies have also linked white matter alterations to impaired sleep quality in individuals with PTSD [66] and mTBI [67,68], revealing associations between poor sleep quality and decreased FA in several main white matter fiber tracts. However, the link between sleep quality and WM microstructure in the context of PTSD and mTBI remains largely unknown.…”