Breakdown of Inter-Hemispheric Connectivity Is Associated with Posttraumatic Symptomatology and Memory Impairment.

Rotem Saar-Ashkenazy,Yael Jacob,Hadar Shalev,Jonathan Guez,Ilan Shelef,Ronel Veksler,Alon Friedman,Jonathan E Cohen,Christian Schmahl

doi:10.1371/journal.pone.0144766

Abstract

Altered brain anatomy in specific gray-matter regions has been shown in patients with posttraumatic stress disorder (PTSD). Recently, white-matter tracts have become a focus of research in PTSD. The corpus callosum (CC) is the principal white-matter fiber bundle, crucial in relaying sensory, motor and cognitive information between hemispheres. Alterations in CC fibers have been reported in PTSD and might be assumed to underlie substantial behavioral and cognitive sequelae; however most diffusion tensor imaging (DTI) studies in adult-onset PTSD failed to address the clinical correlates between imaging and PTSD symptoms severity, behavioral manifestation and cognitive functions. In the current study we examined (a) to what extent microstructural integrity of the CC is associated with memory performance and (b) whether imaging and cognitive parameters are associated with PTSD symptom severity. DTI data were obtained and fractional anisotropy (FA) values were computed for 16 patients and 14 controls. PTSD symptom severity was assessed by employing the clinician administered PTSD scale (CAPS) and memory was tested using a task probing item and associative memory for words and pictures. Significant correlations were found between PTSD symptoms severity, memory accuracy and reaction-time to CC FA values in the PTSD group. This study demonstrates meaningful clinical and cognitive correlates of microstructural connectivity. These results have implications for diagnostic tools and future studies aimed at identifying individuals at risk for PTSD.

Highlights

Post-traumatic stress disorder (PTSD) is a debilitating condition that can develop in response to an acute traumatic event and is characterized by re-experiencing, avoidance, negative alterations in cognition and mood and hyper-arousal [1]
A common parameter obtained from Diffusion tensor imaging (DTI) measurements is fractional anisotropy (FA), which is a quantitative indicator of white matter integrity, reflecting fiber density, axonal diameter, and myelination [12,13,14,15,16]
The results of the current study demonstrated specific correlations between PTSD symptoms severity and behavioral memory measurements (ADI, RT) to white-matter microstructural integrity (FA)

Summary

Introduction

Post-traumatic stress disorder (PTSD) is a debilitating condition that can develop in response to an acute traumatic event and is characterized by re-experiencing, avoidance, negative alterations in cognition and mood and hyper-arousal [1]. The majority of studies testing the exact structural and functional topography of white-matter in PTSD used brain-magnetic resonance imaging (bMRI) that allowed volumetric/area measurements. Several studies in PTSD have shown a reduction in the volume and/or area of the corpus callosum (CC), with or without generalized white-matter atrophy [6,7,8,9,10,11]. While many of these studies were based on volumetric measuring of white-matter, recently, the focus has been shifted to studying the integrity of white-matter tracts. A common parameter obtained from DTI measurements is fractional anisotropy (FA), which is a quantitative indicator of white matter integrity, reflecting fiber density, axonal diameter, and myelination [12,13,14,15,16]

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