Objective Taking the hippocampus as seed,to investigate the characteristics of white matter in patients with major depressive disorder (MDD) and bipolar depression (BD).Methods 33 MDD and BD according with the Fourth Edition of Diagnostic and Statistical Manual of Mental Disorders diagnostic criteria,accompanying with 33 healthy controls (HC) matching with age,sex and education years were analyzed.All subjects underwent MRI scanning,acquiring diffusion tensor imaging (DTI)data.Taking the hippocampus as seed,to adopt diffusion tensor fiber tracing by DSIstudio to obtain and calculate basic index of DTI,then find the differences among three groups;furthermore,calculating the fiber number (FN) evaluating the connective strength between areas between hippocampus and other areas.Additionally,Pearson correlation analysis was used to analyses the relationship between the difference index and clinical characteristics.Results Compared with HC,radial diffusivity (RD) in the left hippocampus had significant difference (P=0.014)in BD group.While no significance parameter was found between MDD group and the other two groups.Compared with HC group,the reduction of FN value in MDD patients mainly exists in left inferior frontal gyrus(0(0,25)vs.0(0,1),P=0.018)and left middle occipital gyrus (38.6±6.7 vs.26.9±25.6,P=0.015).Compared with HC,FN value of BD increase in the left parahippocampal gyms (47.2± 24.0 vs.65.8 ± 30.1,P=0.007) and tongue gyrus (50.4 ± 33.2 vs.74.2 ± 35.9) in BD (P=0.012).Pearson correlation analysis found that RD mean of left hippocampus remain positively correlated with the duration of disease in BD group (r=0.418,P=0.016).Conclusions BD has some changes mainly in the left hippocampus,which exists myelin sheath degeneration and the alteration of white matter fiber connected with left parahippocampal gyrus and tongue gyrus,while MDD shows some differences of connectivity between left hippocampus and frontal lobe,and between right hippocampus and occipital lobe as well.

Objective Taking the hippocampus as seed,to investigate the characteristics of white matter in patients with major depressive disorder (MDD) and bipolar depression (BD).Methods 33 MDD and BD according with the Fourth Edition of Diagnostic and Statistical Manual of Mental Disorders diagnostic criteria,accompanying with 33 healthy controls (HC) matching with age,sex and education years were analyzed.All subjects underwent MRI scanning,acquiring diffusion tensor imaging (DTI)data.Taking the hippocampus as seed,to adopt diffusion tensor fiber tracing by DSIstudio to obtain and calculate basic index of DTI,then find the differences among three groups;furthermore,calculating the fiber number (FN) evaluating the connective strength between areas between hippocampus and other areas.Additionally,Pearson correlation analysis was used to analyses the relationship between the difference index and clinical characteristics.Results Compared with HC,radial diffusivity (RD) in the left hippocampus had significant difference (P=0.014)in BD group.While no significance parameter was found between MDD group and the other two groups.Compared with HC group,the reduction of FN value in MDD patients mainly exists in left inferior frontal gyrus(0(0,25)vs.0(0,1),P=0.018)and left middle occipital gyrus (38.6±6.7 vs.26.9±25.6,P=0.015).Compared with HC,FN value of BD increase in the left parahippocampal gyms (47.2± 24.0 vs.65.8 ± 30.1,P=0.007) and tongue gyrus (50.4 ± 33.2 vs.74.2 ± 35.9) in BD (P=0.012).Pearson correlation analysis found that RD mean of left hippocampus remain positively correlated with the duration of disease in BD group (r=0.418,P=0.016).Conclusions BD has some changes mainly in the left hippocampus,which exists myelin sheath degeneration and the alteration of white matter fiber connected with left parahippocampal gyrus and tongue gyrus,while MDD shows some differences of connectivity between left hippocampus and frontal lobe,and between right hippocampus and occipital lobe as well.