Positive association between local brain hypercorrelations and posttraumatic stress disorder symptom severity

Previous studies have documented neural network anomalies in posttraumatic stress disorder (PTSD) characterized by hypercorrelated interactions across brain areas, relative to controls. Here, we evaluated and compared local, intra-area(s), interactions by computing cross-correlations derived from prewhitened resting-state 3 T fMRI BOLD time series within 84 brain regions (35 cortical areas and 7 subcortical nuclei per hemisphere) in 15 veterans with PTSD and 21 healthy controls. We found that intra-area correlations were significantly higher in PTSD, as compared with controls, indicating a restriction in local network flexibility. PTSD symptom severity was positively and significantly associated with increased local correlations, most prominently in frontal and limbic areas. NEW & NOTEWORTHY This study documented that, relative to healthy brain functioning, posttraumatic stress disorder (PTSD) is associated with increased local (intra-area) correlations in the cortex and subcortex. Remarkably, PTSD symptom severity was positively and significantly associated with increased correlations. These findings complement previous research documenting hypercorrelated interactions across brain areas and suggest a potential benefit of interventions aimed at decorrelating brain networks to a normal state.