Cortical Network Disruption is Minimal in Early Stages of Psychosis

Abstract

Background and Hypothesis: Chronic schizophrenia is associated with white matter disruption and topological reorganization of cortical connectivity but the trajectory of these changes over the disease course are poorly understood. Current white matter studies in first-episode psychosis (FEP) patients using diffusion magnetic resonance imaging (dMRI) suggest such disruption may be detectable at the onset of psychosis, but specific results vary widely and few reports have contextualized their findings with direct comparison to chronic patients. Here, we test the hypothesis that structural changes are not a significant feature of early psychosis. Study Design: Diffusion and T1-weighted 7T MR scans were obtained from N=113 (61 FEP patients, 37 controls, 15 chronic patients) recruited from an established cohort in London, Ontario. Voxel- and network-based analyses were used to detect changes in diffusion microstructural parameters. Graph theory metrics were used to probe changes in the cortical network hierarchy and to assess the vulnerability of hub regions to disruption. Experiments were replicated with N=167 (111 patients, 56 controls) from the Human Connectome Project - Early Psychosis (HCP-EP) dataset. Study Results: Widespread microstructural changes were found in chronic patients, but changes in FEP patients were minimal. Unlike chronic patients, no appreciable topological changes in the cortical network were observed in FEP patients. These results were replicated in the early psychosis patients of the HCP-EP datasets, which were indistinguishable from controls on nearly all metrics. Conclusions: The white matter structural changes observed in chronic schizophrenia are not a prominent feature in the early stages of this illness.