Cortical inhibition deficits in recent onset PTSD after a single prolonged trauma exposure

Abstract

A variety of structural abnormalities have been described in post traumatic stress disorder (PTSD), but only a few studies have focused on cortical thickness alterations in recent onset PTSD. In this study, we adopted surface-based morphometry (SBM), which enables an exploration of global structural changes throughout the brain, in order to compare cortical thickness alterations in recent onset PTSD patients, trauma-exposed subjects but without PTSD, and normal controls. Moreover, we used region of interest (ROI) partial correlation analysis to evaluate the correlation among PTSD symptom severity and significant changes of cortical thickness. The widespread cortical thickness reduction relative to the normal controls were found in bilateral inferior and superior parietal lobes, frontal lobes, hippocampus, cingulate cortex, and right lateral occipital lobes in trauma survivors, whereas cortical thickness was only increased in left calcarine cortex in PTSD group. The average cortical thickness of hippocampus and cingulate cortex decreased by 10.75% and 9.09% in PTSD, 3.48% and 2.86% in non PTSD. We further demonstrated that the cortical thicknesses of bilateral ACC and PCC, superior frontal lobes, and hippocampus are negatively correlated with CAPS scores in all trauma survivors. Our study results suggest that stress widens cortical thinning regions and causes more serious effect in recent onset PTSD than non PTSD. It also shows that the cortical thinning in recent onset PTSD predicts the symptom severity.

Keywords: Cortical thickness; Recent onset PTSD; Surface-based morphometry.

Fig. 1

Cortical thickness difference between the PTSD patients and the normal controls. Region abbreviations from FreeSurfer model: SFG, superior frontal gyrus; HiG, hippocampal gyrus; IPL, inferior parietal lobes; ACC, anterior cingulate cortex; PCC, posterior cingulate cortex; SFG, superior frontal gyrus; RMFG, rostral middle frontal gyrus; LOG, lateral occipital gyrus. The T value color was overlaid on the reconstruction image, and the color bar was shown at the bottom. T values in voxelwise statistical maps were calculated by a general linear model of cortical thickness at each voxel covarying for age and gender. Indicated regions in yellow illustrate where the cortices of PTSD patients are thicker than that of the normal controls at corrected p < 0.05 (FDR corrected), while the indicated region in blue illustrates where the cortices of PTSD patients are thinner than that of the normal controls at corrected p < 0.05 (FDR corrected). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Fig. 2

The cortical thickness difference between PTSD group and non-PTSD group. Region abbreviations from FreeSurfer model: SFG, superior frontal gyrus; HiG, hippocampal gyrus; IPL, inferior parietal lobes; ACC, anterior cingulate cortex; PCC, posterior cingulate cortex; SFG, superior frontal gyrus; RMFG, rostral middle frontal gyrus; LOG, lateral occipital gyrus. The T value color was overlaid on the reconstruction image, and the color bar was shown at the bottom. The age and gender effects were removed by regression.

Fig. 3

Correlations between CAPS and regions thickness analysis. X-axis represents the mean cortical thickness where the cortex with significant change. Y-axis represents the CAPS score value, the Pearson's correlation analysis was used, the r² value was shown in the top right corner. The green circles represent the absolute regions values in the left hemisphere. The red stars represent the absolute regions values in the right hemisphere. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)