A Multimodal Magnetic Resonance Imaging Study On Different Schizophrenia Symptom Dimensions In Patients With First-episode Schizophrenia

Part I opposite effective connectivity in the posterior cingulate and medial prefrontal cortex between first-episode schizophrenic patients with suicide risk and healthy controlsObjective:The schizophrenic patients with high suicide risk are characterized by depression, better cognitive function, and prominent positive symptoms. However, the neurobiology basis of suicide attempts in schizophrenia is not clear. The suicide in schizophrenia is implicated in the defects in emotional process and decision-making, which are associated with prefrontal-cingulate. In order to explore the possible neurobiology basis of suicide in schizophrenia, we investigated the correlation between the prefrontal-cingulate and suicide risk in schizophrenia via dynamic casual modelling.Methods:Participants were33first-episode schizophrenic patients comprising of a high suicide risk group (N=14) and a low suicide risk group (N=19). A comparison group of healthy controls (N=15) were matched for age, gender and education. N-back tasking functional magnetic resonance imaging data was collected.Results:Compared with healthy controls group, the two patients groups showed hyperactivity (decrease suppression) during2-back task state versus baseline state in the left posterior cingulate and medial prefrontal cortex; the hyper-connectivity from the left posterior cingulate cortex to the left medial prefrontal cortex both exist in the two schizophrenic patients group, but hypo-connectivity in the opposite direction only exist in schizophrenic patients with high suicide risk group.Conclusion:The hyper-connectivity from the left posterior cingulate cortex to the left medial prefrontal cortex may suggest that the abnormal effective connectivity was associated with risk for schizophrenia. The hypo-connectivity in the opposite direction may represent a possible correlate of increased vulnerability to suicide attempt. Part II A Multimodal Magnetic Resonance Imaging Study on Positive and Negative Symptoms in First-episode SchizophreniaObjective:As expressed by Kraepelin, to fundamentally understand schizophrenia one must relate the observable symptoms of the disorder to the unobservable neural pathophysiology. Symptom dimensions may reveal patterns of association with brain functioning which are not apparent when patient data are averaged into a single group and symptom heterogeneity abscures differnces with a comparison group. Kraepelin, Bleuler and others presume that patients with similar symptoms also shared underlying pathology. Our goals are to identify the possible neurobiology basis of different symptom dimensions in schizophrenia via multimodal imaging analysis, and look for the possibility of individualized treatment according to the clinical feature of patients.Methods:Participants were52first-episode schizophrenic patients comprising of positive symptom group (N=35) and negative symptom group (N=17). A comparison group of healthy controls (N=38) were matched for age, gender and education. Structural magnetic resonance imaging, rest state and N-back tasking functional magnetic resonance imaging data were collected. Voxel-based morphometry analysis was used to detect group differences in gray matter volume. Then the resulting brain regions served as regions of interest for further functional connectivity analysis in all subjects. We also identified the different task-related brain activity under n-back task.Results:Compared to healthy controls group, the two schizophrenic patients groups shared significantly increased gray matter volume in dorsolateral prefrontal cortex (DLPFC). Significant connectivity difference among three groups were the connectivities between the right DLPFC and right medial prefrontal cortex (MPFC), the right DLPFC and right caudate. During N-back task paradigm, the two patients groups showed lower task-related suppression in DLPFC/anterior cingulate cortext (ACC), and posterior cingulate cortext (PCC) than healthy controls group; the negative symptom group showed higher task-related activition in DLPFC than the positive symptom group and healty control group. Conclusion:The structural and functional lesion in DLPFC mayplay an important role in the pathophysiological procedure of negative symptom and cognitive function. The cortical midline strctures may implicate in the neurobiological basis of positive symptom.