| Objective: Schizophrenia(SZ)is a common and serious mental disorder in psychiatry,but its pathogenesis is yet to be identified.A growing body of research suggests that schizophrenia is a disease characterized primarily by changes in the brain.Therefore,it is very important to use appropriate image analysis methods to find the imaging features of brain diseases.But the traditional voxel-based neuroimaging analysis is not very effective due to the folds of the cerebral cortex.As the image analysis technology advances,surfacebased algorithms were developed to solve this issue.For the structural imaging,the cortical thickness and the cortical surface area,which constitute the cortical volume,can be obtained through surface-based morphological analysis.Previous studies have found abnormal cortical volume in multiple brain regions in patients with SZ,but it is not clear whether the change is due to thickness or surface area.Cortical thickness and surface area are affected by independent genetic factors and have different developmental trajectories.The study of the changes of cortical thickness and surface area can provide more information about changes of neural structure for SZ patients.However,there are few studies on the changes of cortical thickness or surface area in SZ patients without taking medicine,and the results of existing studies on this disease are inconsistent.For functional imaging,2D regional homogeneity is an new index of resting-state functional imaging,and it is also a new functional parameter deriving from 3D regional homogeneity of cortical surface algorithm.Besides,it is an index of synchronization of time series between a vertex on the cortex and the six adjacent vertices around it,and it is thought to be the short-range functional connectivity in the connectome.Also,it is a highly sensitive,repeatable and reliable short-range functional connectivity index.With the distinctive advantages of2 d Re Ho,it can show the structural morphology of the local cerebral cortex and neurobiologically reflect the complexity of information processing.In addition,there is growing evidence that 2d Re Ho alteration is associated with pathophysiology of mental illness.So the study of 2d Re Ho in SZ patients is very important to identify the biological mechanism of SZ.However,the analysis of 2d Re Ho in patients with SZ has not been found in relevant studies.This study aims to identify the imaging features of cerebral cortex in patients with SZ that did not take medicine,by using surface-based analysis,combined with structural and functional MRI.This study provides basis for clinically finding changes of radiological features in SZ patients and discovering the therapeutic targets.Methods: A total of 67 unmedicated SZ patients aged 13-45 years who met the diagnostic and Statistical Manual of mental disorders-IV Version(DSM-IV)diagnostic criteria were enrolled in this study.At the same time,170 age and gender matched healthy controls(HC)were recruited through advertisements.Demographic data collection,clinical symptoms and cognitive function evaluation and magnetic resonance scanning were performed on all subjects.All subjects were scanned by high-resolution structural magnetic resonance imaging and resting state functional imaging using GE 3.0T magnetic resonance machine.The collected image data were preprocessed by CCS(Connectome Computation System)pipeline.The cortical thickness,cortical surface area and cortical surface-based regional homogeneity(2d Re Ho)values of all subjects were calculated.The structural and functional data were statistically analyzed by Free Surfer software and Dpabisurf software respectively.The differences of cortical thickness,cortical surface area and 2d Re Ho values between unmedicated SZ patients and HC were compared by two sample T test with age and gender taken as covariates to find the brain regions with abnormal cortical structure and function in unmedicated SZ patients.Then the general demographic and clinical variables and their correlation with imaging indicators were statistically analyzed by SPSS software.Results: 1.Demographic data showed that there was no significant difference in age and gender between SZ patients and HC patients(P > 0.05),and there were significant differences in the scores of all clinical scales,such as Brief Psychiatric Rating Scale(BPRS),Hamilton Depression Rating Scale 17 item(HAMD-17),The scores of HAMD-17 item and Wisconsin Card Sorting Test(WCST)had significant abnormal changes(P <0.05).2.The 2dreho values of unmedicated SZ patients were significantly lower than those of HC in several brain regions,suggesting that unmedicated SZ patients had extensive functional changes in the primary visual cortex,auditory cortex,somatosensory and somatomotor cortex and association corticies,which indicated that the synchronization of local neuron activity in the related cerebral cortex decreased,the short-distance functional connection decreased,the functional separation decreased and the integration increased,and the complexity of information processing increased.The results provide new imaging evidence for further study of the pathophysiological mechanism of SZ,and provide exact imaging basis and theoretical support for further exploration of the pathogenesis of SZ.3.Exploratory partial correlation analysis in unmedicated SZ patients showed that the cortical thickness of right lingual gyrus and left dorsomedial prefrontal cortex was positively correlated with HAMD factor score of core depression(right lingual gyrus: r = 0.368,P =0.010;left dorsomedial prefrontal cortex: r = 0.360,P = 0.010);the cortical thickness of the left dorsomedial prefrontal cortex was positively correlated with the total score of HAMD(r = 0.322,P = 0.025).The surface area of the right superior temporal gyrus was negatively correlated with the 2dreho value of the right primary visual cortex and association cortex(r =-0.406,P = 0.005),with the right primary somatosensory motor cortex and association cortex(r =-0.276,P = 0.034),and with the left primary visual cortex and association cortex(r =-0.355,P = 0.014)?Conclusion: The conclusion includes three parts.First,the value of cortical thickness in the left dorsomedial prefrontal cortex and the right lingual gyrus in the SZ patients without taking medicine was significantly higher than that in HC,suggesting a localized increase in cortical thickness of affective brain region and primary visual area.The value of cortical surface area of these patients was significantly lower than that of HC in the right superior temporal gyrus(STG),indicating an abnormal localized reduction in the cortical surface area of primary auditory cortex.The results showed that there were localized structural changes in cerebral cortex in SZ patients without taking medicine.These abnormalities,probably involving in the pathophysiological processes of SZ,are neurobiological changes of SZ.Structural abnormalities in the cerebral cortex were found in these patients,which impaired the functions of the corresponding brain region,and finally led to the disease.The results of this study not only provide new imaging data for further exploring the pathophysiological mechanism of SZ,but also provide basis for clinically finding changes of radiological features in SZ patients and discovering the therapeutic targets.Second,the values of 2d Re Ho in SZ patients without taking medicine in multiple brain regions were significantly lower than those in HC,indicating brain functional damage to primary visual cortex,auditory cortex,somatosensory cortex,somatomotor cortex,and its association cortex.The results showed decreased synchronicity of the related cortical neurons,reduced short-range functional connectivity,decreased functional segregation,increased functional integration,and increased complexity of information processing.The results of this study provide new imaging evidence for the further studies on the pathophysiological mechanism of SZ and theoretical basis for identifying pathogenesis of SZ.Third,the correlation between the right primary auditory cortex and auditory cortex,somatosensory cortex in SZ patients without taking medicine suggests an abnormal association between anatomy and function.The surfacebased multimodality imaging method used in this study provides a new approach to develop a better understanding of pathophysiological features of SZ. |
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