The Study Of Electroconvulsive Therapy On The Nodal Degree Of Neural Network In Depression

Background Depression is a common psychiatric disorder characterized by anhedonia,delayed thinking,and somatic symptoms,which severely affects social functioning and diminishes quality of life.Electroconvulsive therapy（ECT）,one of the commonly used forms of neurostimulation in clinical practice,acts rapidly and effectively for depression.However,its exact antidepressant mechanism remains unclear.Neural network plays an important role in emotional and cognitive function.Neural network is modeled as a graph composed of nodes（voxel or cerebral regions）and interactions between nodes（connections）.Nodal Degree（ND）refers to the number of connections of each node,which is an important determinant of the nature of neural network.Resting-state functional Magnetic Resonance Imaging（rs-f MRI）can non-invasively detect neuronal activity and assess the function of neural network,providing an effective tool to elucidate the neural mechanisms underlying the efficacy of ECT.Objective Rs-f MRI was used to investigate the changes of whole-brain voxel node degree before and after ECT and its relationship with depression improvement,to further understand the antidepressant mechanism of ECT.Methods 42 depressive patients receiving ECT and 42 matched healthy controls were enrolled for magnetic resonance imaging scans and the Hamilton Rating Scale for Depression（HRSD）assessment at two time points（corresponding to pre-ECT and post-ECT）.The index of nodal degree（IND）of the whole-brain voxel were calculated on the magnetic resonance imaging data and the permutation test of two-factor repeated-measure analysis of variance was used to compare the cerebral regions with the interaction between groups and time points.Pearson’s correlation analysis was applied to determine the correlation between the changed IND rate of significant cerebral regions and HRSD scores.Verification analysis was evaluated in a second independent cohort included 23 depressive patients receiving ECT.Results The HRSD scores were decreased after ECT in depressive patients（t = 15.17,p < 0.001）.the two-factor repeated-measure analysis of variance showed significant interaction between the two groups and two time points of IND in the bilateral angular cortex（AG）,precuneus,inferior frontal gyrus（IFG）and the right superior frontal gyrus（SFG）.Post hoc analysis showed IND in these brain regions were increased after ECT compared with pre-ECT（t = 6.21,p < 0.001）.Further correlation analysis showed the increase of IND in the right AG was negatively correlated with the change of HRSD scores（r =-0.31,p = 0.049）,and the increase of IND in the left precuneus was negatively correlated trend with the change of HRSD scores（r =-0.27,p = 0.085）.In addition,validation cohort analysis showed increased IND in the bilateral AG,precuneus,frontal lobes,parietal lobes and temporal lobes,and increased IND in the left precuneus was negatively associated with the change of HRSD scores（r =-0.43,p =0.041）,the increase of IND in the right AG was negatively correlated trend with the change of HRSD scores（r =-0.37,p = 0.084）.Conclusion ECT increased the IND of bilateral AG,precuneus,IFG and right SFG.The increased IND of right AG and left precuneus were associated with changed depression improvement.The functional changes of the AG and precuneus may be an important therapeutic mechanism,this study provides insights into the potential targets of ECT for antidepression.