Disruption Of White Matter Integrity In First-episode Schizophrenia As Revealed By Fiber Tractography

Background:The integrity connection of white matter is the basis of the normal function in our brain. Previous research has suggested that schizophrenia had abnormalities in different gray matter regions.But Evidence is growing that schizophrenia might be a disease of disconnection between these brain regions.So schizophrenia may have a degree of of white matter fiber structure abnormalities. But findings have been in controversy.Objective:(1)To explore the microstructural changes of whole brain white matter by diffusion tensor imaging (DTI) and tract-based spatial statistics (TBSS) in the first-episode schizophrenia and controls.(2)To explore the relationship between the FA values of patients and psychiatric symptoms, cognitive function.(3) To present the3D reconstructions of white matter fiber bundles.Methods:27patients with first-episode schizophrenia and20age/gender matched healthy people were enrolled by the strict criteria. For all patients, the positive and negative syndrome scale(PANSS) was used to assess their psychiatric symptoms, For all eligible participants, neuropsychological tests consist of trial making test, Stroop test, Wisconsin card sorting test, stop signal task and running memory task were used to assess their cognitive state in this study. We employed DTI to examine the white matter changes in both groups and take fractional anisotropy (FA) as the DTI index. DTI images were analyzed by TBSS toolbox which performs voxel-by-voxel whole brain analysis in FSL5.0to compare FA between patients and controls. Clinical association of FA values with psychiatric symptoms and cognitive function was analyzed using Spearman’s correlation in SPSS18.0. Additionally, the white matter fiber bundles were reconstructed by the advanced software of Diffusion Toolkit and Trackvis.Results:(1) The FA level in the bilateral body of corpus callosum, right anterior corona radiata, left cingulum, left genu of corpus callosum, bilateral superior corona radiata, right anterior limb of internal capsule in first-episode schizophrenia group was significantly lower than that in control group (p<0.05);(2) Compared with control group, first-episode schizophrenia patients showed significantly worse performance in almost all of neuropsychological tests scores (p<0.05), except the stop-singal reaction time and go-signal reaction time in stop signal task(p>0.05);(3) In first-episode schizophrenia group, the total score of PANSS was correlated negatively with mean FA value (r=-0.39, p=0.04), while the negative subscale score of PANSS was positive correlated with FA value in superior corona radiata (r=0.44, p=0.02). In the neuropsychological tests, go-signal reaction time in stop signal task was negatively correlated with FA value in the body of corpus callosum (r=-0.48, p=0.02) and right anterior limb of internal capsule (r=-0.42, p=0.04), while the number of words reading in Stroop test is positive correlated with FA value in superior corona radiata (r=0.43, p-0.03). In addition, the rate of correct answers correlated positively with FA value in left cingulum (r=0.54, p=0.01).(4) The mean fiber length of the bilateral body of corpus callosum in first-episode schizophrenia group was significantly shorter than that in control group (p<0.05).Conclusion:(1) The first-episode schizophrenia exhibited significan-tly lower mean FA values than healthy subjects in white matter of bilateral body of corpus callosum, right anterior corona radiata, left cingulum, left genu of corpus callosum, bilateral superior corona radiata, and right anterior limb of internal capsule.(2) Psychiatric symptoms and some of cognitive functions were significantly correlated to mean FA and several fiber bundles FA of those first-episode schizophrenia patients.(3) The white matter microstructure and fiber connectivity abnormalities were occurred in early phase of schizophrenia, which might be the consequence of demyelination.