Comparative Study Of Regional Cerebral Blood Flow,Functional Activity And Functional Connectivity Between Patients With Unipolar Disorder And Bipolar Depressive Disorder

ObjectiveUsing multimodal magnetic resonance technique,including with arterial spin labeling and amplitude of low frequency fluctuation(ALFF)and functional connectivity(FC)of resting state functional magnetic resonance,to explore the difference of resting state local cerebral blood flow(CBF)and local function and functional connection between patients with bipolar disorder(BD)type II depression and patients with unipolar dsiorder(UD).They provided theoretical basis for the pathophysiological mechanism and objective diagnosis of patients with unipolar and bipolar depression.MethodsEighty-eight unmedicated patients with BDII depression,95 unmedicated patients with UD,and 96 healthy controls(HC)were scanned by arterial spin labeled perfusion imaging and resting-state functional magnetic resonance imaging.The data were preprocessed,the CBF and the ALFF of BDII depression group,UD group,and healthy control group were calculated.The CBF values and the ALFF values of the three groups were compared by one-way ANOVA,and the difference of brain regions were compared by post-hoc analysis.The correction method was based on the Gaussian random field theory,and the correction threshold was set as follows: voxel level p<0.001,clustering p<0.05,with p<0.05 means the difference is statistically significant.The peak coordinates of the three groups of CBF values and ALFF values were used as seed points,and small balls with a radius of 6 were drawn for functional connection analysis to calculate the FC values of other voxels in the whole brain.The statistical method and correction method were the same as before.Then the CBF value,ALFF value and FC value of different brain regions were correlated with the clinical variables of the patient group by partial correlation analysis(p< 0.05).Finally,CBF,ALFF and FC with statistical differences between groups were used as characteristic values,and support vector machine(SVM)classification method based on pattern recognition was used to distinguish BDII depression phase patients,UD patients and HC.Results(1)Comparison of CBF values: the brain regions with different CBF values among the three groups were the left posterior cerebellar lobe and the left middle temporal gyrus.Posthoc analysis showed that the CBF values in the left posterior cerebellar lobe and left middle temporal gyrus of BDII depression group and UD group were both higher than that in the healthy control group,and there was no statistical difference between BDII depression group and UD group.(2)Comparison of ALFF values: the brain regions with different ALFF values among the three groups were the left posterior cerebellar lobe.Post-hoc analysis showed that ALFF value in the left posterior cerebellar lobe of BDII depression group was lower than that in the HC group and UD group,and ALFF value in the left posterior cerebellar lobe of UD group was lower than that in the HC group.(3)Comparison of FC values:(1)The different brain regions of CBF(the left posterior cerebellar lobe and the left middle temporal gyrus)are used as seed points,there was a significant difference in FC between the left posterior cerebellar lobe and the left inferior frontal gyrus among the three groups.Post-hoc analysis of the above brain region showed that FC value in the left posterior cerebellar lobe-left inferior frontal gyrus of BDII depression group and UD group were lower than that in the healthy control group;The FC value in the left posterior cerebellar lobe-left inferior frontal gyrus of BDII depression group was lower than that in the UD group.There was no significant difference in the FC value of the left middle temporal gyrus among the three groups.(2)The different brain regions of ALFF(the left posterior cerebellar lobe)was used as seed points for FC analysis,no significant statistical difference was found between the three groups.(4)Correlation analysis: The CBF value of the left middle temporal gyrus in the UD group was positively correlated with Hamilton Depression Rating Scale(r=0.322,p=0.002),and there was no significant correlation of the CBF value and the ALFF value and FC value between other abnormal brain regions and the patients’ clinical information.(5)SVM classification display: By selecting a single parameter CBF,ALFF,FC feature and the fusion of three features for classification,the classification accuracy of BDII depression group and HC group was 70%,60%,65% and 72%,and the classification accuracy of UD group and HC group was 54%,53%,54% and 52%.By selecting a single parameter ALFF,FC feature and the fusion of the two features for classification,the classification accuracy of BDII depression group and UD group is 66%,56% and 68%,respectively.Conclusion1.Both unipolar and bipolar depression patients have abnormally increased blood perfusion in the middle temporal gyrus,which is related to the severity of their depression.2.Both unipolar and bipolar depression patients have perfusion of the posterior cerebellar blood flow,abnormal local functional activity,and the destruction of the functional connection between the posterior cerebellum and the inferior frontal gyrus,suggesting that there may be overlapping pathophysiological basis.3.The multi-feature fusion classification of CBF,ALFF and FC based on SVM is helpful to the objective diagnosis of bipolar depression.