The dissociative subtype of posttraumatic stress disorder is associated with subcortical white matter network alterations

Abstract

Posttraumatic stress disorder (PTSD) is characterized by intrusions, avoidance, and hyperarousal while patients of the dissociative subtype (PTSD-D) experience additional dissociative symptoms. A neurobiological model proposes hyper-inhibition of limbic structures mediated by prefrontal cortices to underlie dissociation in PTSD. Here, we tested whether functional alterations in fronto-limbic circuits are underpinned by white matter network abnormalities on a network level. 23 women with PTSD-D and 19 women with classic PTSD participated. We employed deterministic diffusion tractography and graph theoretical analyses. Mean fractional anisotropy (FA) was chosen as a network weight and group differences assessed using network-based statistics. No significant white matter network alterations comprising both frontal and limbic structures in PTSD-D relative to classic PTSD were found. A subsequent whole brain exploratory analysis revealed relative FA alterations in PTSD-D in two subcortical networks, comprising connections between the left amygdala, hippocampus, and thalamus as well as links between the left ventral diencephalon, putamen, and pallidum, respectively. Dissociative symptom severity in the PTSD-D group correlated with FA values within both networks. Our findings suggest fronto-limbic inhibition in PTSD-D may present a dynamic neural process, which is not hard-wired via white matter tracts. Our exploratory results point towards altered fiber tract communication in a limbic-thalamic circuit, which may underlie (a) an initial strong emotional reaction to trauma reminders before conscious regulatory processes are enabled and (b) deficits in early sensory processing. In addition, aberrant structural connectivity in low-level motor regions may present neural correlates for dissociation as a passive threat-response.

Developmental Delays in Socio-Emotional Brain Functions in Persons with an Intellectual Disability: Impact on Treatment and Support

“…However, other psychiatric disorders, such as social anxiety disorders, dissociative disorders, or personality disorders, may require the maturation of higher-order social brain networks and so cannot be found earlier than age 5 years [ 62 , 63 , 64 ]. Social anxiety disorders require perspective-taking skills located in the Theory of Mind network [ 62 ].…”

“…Social anxiety disorders require perspective-taking skills located in the Theory of Mind network [ 62 ]. Dissociative disorders are associated with subcortical white matter alterations within the higher limbic system [ 63 , 64 ]. Conduct disorders may progress to antisocial personality disorders during adolescence/early adulthood [ 65 ].…”

Neural correlates of acute post-traumatic dissociation: a functional neuroimaging script-driven imagery study

“…8 Altered brain circuity was further reported between the right supramarginal gyrus and the thalamus, 9 of which the latter region depicted lower fractional anisotropy in a network with the left amygdala and hippocampus, correlating negatively with self-reported depersonalisation experiences. 10 Such brain activation patterns during the resting state might detect differential connectivity networks, but cannot establish direct causal relationships between the observed alterations and the occurrence of dissociative symptoms. To achieve better causal attribution, symptom induction during data acquisition is needed.…”

Neurobiological Alterations in Females With PTSD: A Systematic Review

“…Altered activity in the vmPFC may suggest deficits in amygdala regulation ( 89 ), leading to challenges in downregulating excessive arousal, and hypervigilance among some females with PTSD. This presentation is heightened by deficits in synchronization between key brain regions including the amygdala, hippocampus, thalamus, and the brain stem ( 61 ), proposed to be linked to the experience of dissociation.…”