Effects Of Risperidone On Posteromedial Cortex In Antipsychotic-naive First-episode Schizophrenia

Schizophrenia is a serious and disabling mental disease characterized by sensory,thought,emotion and behavioral disorders.Symptoms of schizophrenia can be divided into positive symptoms,negative symptoms and cognitive impairment.Among them,the positive symptoms include hallucination,delusion.Negative symptoms include reduction in spontaneous speech,apathy,withdrawal and impaired motivation.In addition,schizophrenia patients also have cognitive impairment including episodic memory,working memory and attention.Schizophrenia imposes a heavy burden on the patients,their family and society.Although the harm of schizophrenia is very serious,but its etiology and pathogenesis is not fully understood,which also brings obstacles to the prevention and treatment of schizophrenia.Brain dysfunction is widely believed to exist in schizophrenia.With the development of magnetic resonance imaging,rest-state functional magnetic resonance imaging based on blood oxygen level dependence has been widely used in the study of schizophrenia.In current study,dynamic amplitude low-frequency fluctuation and functional connectivity analysis were used to explore the pathological mechanism of schizophrenia,and to find possible biomarkers and to explore the effect of antipsychotic drugs.The context mainly includes the following two parts1.The method of dynamic amplitude low-frequency fluctuation analysis based on sliding window was used to detect the temporal variability of intrinsic brain activity in patients with schizophrenia.The results showed that the dynamic amplitude low-frequency fluctuation in the bilateral precuneus decreased in patients with schizophrenia compared with healthy controls.These results suggest that there is a difference in the dynamic amplitude low-frequency fluctuation pattern between patients with schizophrenia and healthy controls,and the precuneus plays an important role as a biomarker of schizophrenia,which is helpful to further understand the pathophysiology of schizophrenia2.Based on the previous study,we found that schizophrenia has an abnormal dynamic amplitude low-frequency fluctuation in the precuneus,which is an important part of the posteromedial cortex.In this study,we investigate the differences in the posteromedial cortex subregion between antipsychotic-naive first-episode schizophrenia and healthy controls with functional connectivity,and analyze the effect of risperidone treatment on the functional connectivity in longitudinal studies.The results showed that relative to the healthy controls,patients at baseline showed decreased functional connectivity between the posteromedial cortex subregions and several brain regions including the parahippocampal gyrus,lingual gyrus,thalamus,cerebellum,middle temporal gyrus,and superior temporal gyrus.After 8-weeks' risperidone monotherapy,patients showed increased functional connectivity between posterior cingulate cortex and the bilateral thalamus and the left lingual gyrus,comparing with baseline statement.In addition,functional connectivity between posterior cingulate cortex and left lingual gyrus in patients without treatment could predict the rate of positive symptoms scores change.These results suggest that there are functional connectivity differences in the posteromedial cortex in schizophrenia compared with healthy controls.Risperidone chould normalize the functional connectivity in the posterior cingulate gyrus in schizophrenia,but precuneus and retrosplenial cortex were not affected by risperidone.These results indicate the important role of posterior cingulate gyrus as a biomarker in the treatment of schizophrenia and indicate its potential clinical significance in the treatment mechanism of schizophrenia.In conclusion,this study found that there were time-varying dynamic amplitude low-frequency fluctuation differences and abnormalities in the posteromedial cortex in schizophrenia patients compared with healthy controls,which may be potential biomarkers of schizophrenia and explore the pathological mechanism of schizophrenia.At the same time,we found the effect of risperidone on the posteromedial cortex,which might provided some ideas for the treatment of schizophrenia.