Reduced Gray-White Matter Contrast in Chronic Posttraumatic Stress Disorder in World Trade Center Responders

Following the collapse of the World Trade Center (WTC), many people experienced severe trauma and 23% of WTC responders developed posttraumatic stress disorder (PTSD). We hypothesized that gray-white matter contrast (GWC) would be different in participants with PTSD compared with demographically matched trauma-exposed control participants with no history of PTSD.

T1-weighted structural images for 99 WTC responders collected on a 3T Siemen's magnetic resonance imaging scanner were retrieved and segmented to measure global, regional, and voxelwise GWC. Group-level analyses adjusted for the false discovery rate (FDR) (FDR = .05). Area under the receiver operating characteristic curve was reported. To determine correlates of PTSD, we also measured PTSD symptom severity and several putative neuroimaging measures linked to PTSD including cortical fractal dimensions, cortical free water fraction, characteristic path length, and cerebral/cerebellar cortical thickness.

WTC responders with PTSD exhibited reduced cerebral GWC globally (d = 0.47, SE = 0.20, p = 0.022), while vertexwise results showed focal differences (FDR < .05) in the frontal, temporal, and parietal lobes. Among participants with PTSD, analyses identified correlations that passed FDR correction linking GWC with overall PTSD symptom severity (ρ = -0.24) that were strongest when examining re-experiencing symptom severity (ρ = -0.28) and when examining GWC in the pars triangularis (ρ = -0.37). GWC was not associated with cortical fractal dimension, cortical free water fraction, characteristic path length, or cerebral/cerebellar cortical thickness.

Results support emerging research suggesting that PTSD is associated with changes to intracortical health. If replicated, changes in GWC might provide novel treatment targets and could help to support diagnosis in research studies.