White Matter Integrity in Genetic High-Risk Individuals and First-Episode Schizophrenia Patients: Similarities and Disassociations.

Yifang Zhou,Qian Zhou,Kaiyuan Chen,Yanqing Tang,Ye Wang,Naomi Driesen,Jie Liu,Xiaowei Jiang,Fei Wang,Fay Womer,Dahai Wang,Chuan Bai

doi:10.1155/2017/3107845

Abstract

White matter (WM) neuroimaging studies have shown varied findings at different stages of schizophrenia (SZ). Understanding these variations may elucidate distinct markers of genetic vulnerability and conversion to psychosis. To examine the similarities and differences in WM connectivity between those at-risk for and in early stages of SZ, a cross-sectional diffusion tensor imaging study of 48 individuals diagnosed with first-episode SZ (FE-SZ), 37 nonpsychotic individuals at a high genetic risk of SZ (GHR-SZ), and 67 healthy controls (HC) was conducted. Decreased fractional anisotropy (FA) in the corpus callosum (CC), anterior cingulum (AC), and uncinate fasciculus (UF) was observed in both the GHR-SZ and FE-SZ groups, while decreased FAs in the superior longitudinal fasciculus (SLF) and the fornix were only seen in the FE-SZ participants. Additionally, both GHR-SZ and FE-SZ showed worse executive performance than HC. The left SLF III FA was significantly positively correlated with hallucinations, and right SLF II was positively correlated with thought disorder. The presence of shared WM deficits in both FE-SZ and GHR-SZ individuals may reflect the genetic liability to SZ, while the disparate FA changes in the FE-SZ group may represent symptom-generating circuitry that mediates perceptual and cognitive disturbances of SZ and ultimately culminates in the onset of psychotic episodes.

Highlights

Disconnectivity of different brain regions, which is putatively mediated by white matter (WM) abnormalities, is widely considered to be a key feature of schizophrenia (SZ) [1,2,3]
Post hoc analyses revealed decreased fractional anisotropy (FA) in the corpus callosum (CC), anterior cingulum (AC), and uncinate fasciculus (UF) in both the first-episode SZ (FE-SZ) and genetic high-risk for SZ (GHR-SZ) group when compared to the healthy controls (HC) group, with no significant difference in FA between FE-SZ and GHR-SZ participants (Figure 2)
Significant decrease in FA was found in the right superior longitudinal fasciculus (SLF) II, left SLF III, and FX in the FE-SZ participants, but not in GHR-SZ participants, when compared to HC (Figure 2)

Summary

Introduction

Disconnectivity of different brain regions, which is putatively mediated by white matter (WM) abnormalities, is widely considered to be a key feature of schizophrenia (SZ) [1,2,3]. Postmortem histological studies support the involvement of WM abnormalities in the pathophysiology of SZ [4, 5]. Structural MRI studies have implicated WM abnormalities in SZ, demonstrating altered WM volumes in multiple lobes of SZ patients [8,9,10]. Similar WM volumetric changes have been observed in SZ patients experiencing their first psychotic episode (FE-SZ) and in nonpsychotic healthy populations who are at increased genetic high-risk for SZ (GHR-SZ) [11,12,13]. Diffusion tensor imaging (DTI) has further substantiated WM involvement in SZ. In chronic SZ, DTI studies have detected widespread abnormalities in the WM integrity. Despite common WM abnormalities across the stages of SZ, findings from FE-SZ and GHR-SZ populations have

Results

Discussion

Conclusion