S167. ANATOMICAL CONNECTIVITY OF THE VISUOSPATIAL ATTENTIONAL NETWORK IN SCHIZOPHRENIA: A DTI-BASED TRACTOGRAPHY STUDY

Leroux Elise,Sonia Dollfus,Poirel Nicolas

doi:10.1093/schbul/sby018.954

Abstract

BackgroundIn healthy controls (HCs), the visuospatial attentional network consists of fronto-parietal bundles distributed across both hemispheres, but the anatomical organization of this network remains largely unknown in patients with schizophrenia (SZPs). Using diffusion tensor imaging (DTI)-based tractography, we investigated both white matter integrity and the volume of visuospatial attentional pathways in the right and left hemispheres (RH and LH), as well as their structural asymmetry in SZPs and HCs and hypothesized that SZPs would have WM pathway alterations and abnormal structural asymmetry.MethodsThis study included 34 SZPs and 69 HCs. Integrity parameters (fractional anisotropy [FA], radial and mean diffusivity [RD and MD]) and volume were calculated in each fasciculus of this network: the three branches of the superior longitudinal fasciculus (SLFI–III), the inferior longitudinal fasciculus, and the inferior fronto-occipital fasciculus in the RH and LH.ResultsIn SLFII and SLFIII, compared to RH and LH values for SZPs, HCs presented increased FA and/or decreased RD/MD in RH and/or LH. Both SZPs and HCs presented increased FA and decreased RD/MD in the RH compared to the LH in the SLFIII, whereas only HCs had this pattern in the SLFII. Volumes did not differ between groups.DiscussionTo our knowledge, this study is the first to describe the structural hemispheric lateralization/organization of the visuospatial attentional network in SZPs. Our main findings are disrupted structural connectivity in the SLFII associated with abnormal anatomical asymmetry in patients, which could be a substrate of attentional deficits.

Highlights

In healthy controls (HCs), the visuospatial attentional network consists of fronto-parietal bundles distributed across both hemispheres, but the anatomical organization of this network remains largely unknown in patients with schizophrenia (SZPs)
Using diffusion tensor imaging (DTI)based tractography, we investigated both white matter integrity and the volume of visuospatial attentional pathways in the right and left hemispheres (RH and LH), as well as their structural asymmetry in SZPs and HCs and hypothesized that SZPs would have WM pathway alterations and abnormal structural asymmetry
In SLFII and SLFIII, compared to RH and LH values for SZPs, HCs presented increased FA and/or decreased RD/MD in RH and/or LH. Both SZPs and HCs presented increased FA and decreased RD/MD in the RH compared to the LH in the SLFIII, whereas only HCs had this pattern in the SLFII

Summary

Background

Abnormal brain structural alterations and microglial activation are implicated in the pathophysiology of psychosis. Previous studies suggested a link between the level of proinflammatory cytokines and abnormalities in brain structure in patients with schizophrenia, there is no in-vivo study investigating whether microglial activation is linked to morphological brain alterations previously reported in individuals with psychosis and psychosis risk. Methods: In order to address the current gap in the literature, we investigated microglial activation and structural brain abnormalities in key brain regions affected in psychosis (i.e. hippocampus and dorsolateral prefrontal cortex) of a large group of participants (N = 90) including 35 individuals at clinical high risk (CHR) for psychosis, first-episode psychosis (mostly antipsychotic naïve) patients, and healthy volunteers. All the participants underwent a [18F]FEPPA positron emission tomography (PET)

Findings