Diffusion Tensor Imaging And Resting State Functional Magnetic Resonance Imaging Study On Young Patients With Major Depressive Disorder

Object: The aim of this study was to explore the brain functional and structural pathological mechanism in young major depressive disorder, by diffusion tensor imaging resting state functional magnetic resonance imaging techniques.Method: Sixteen participants diagnosed with major depressive disorder (course of disease <=one year) according to DSM-IV and sixteen age and gender-matched healthy controls were assessed using 17-item Hamilton Depression Rating Scale (HAMD), HAMD scores were requested >24 in patients and<7 in controls. Then, MRI scan were obtained ordering to resting state fMRI, DTI, three dimension MRI (3D). A voxel-based method (VBM) was used to analyze the DTI datasets. The newly published ReHo approach (which estimates the temporal homogeneity of regional BOLD signal in the same time series) was applied to preprocess the fMRI datasets. For exploring the FA and ReHo difference between the depression and controls, a ANOVA test was performed on the individual FA values and ReHo maps in a voxel-by-voxel manner. Resulted statistical map was set at a threshold of p<0.01 and a minimum cluster size of 30 voxels.Results: all the patients and controls finished MRI scan. 1. DTI The patient group exhibited significantly lower FA values than healthy comparison subjects in the white matter of the left middle temporal gyrus, right middle frontal gyrus, left medial frontal gyrus, right precentral gyrus, left angular gyrus, left fusiform gyrus, left superior temporal gyrus, right middle temporal gyrus, right sub-gyral, left Insula, left pyramis,. 2. resting state fMRI Compared with control subjects, Patients with depression showed decreased ReHo of blood oxygen level dependent (BOLD) signal in resting brain. The decreased ReHo was distributed over left superior frontal gyrus, right superior frontal gyrus, left middle frontal gyrus, right middle frontal gyrus, left medial frontal gyrus, right medial frontal gyrus, left paracentral lobule, right paracentral lobule, right inferior parietal lobule, left postcentral gyrus, right postcentral gyrus , left middle occipital gyrus, left lingual gyrus, right putamen, right cingulate gyrus, right cuneus, left superior temporal gyrus, right middle temporal gyrus.Conclusion: 1.The DTI findings suggested that abnormalities of brain white matter may be present early in the course of major depressive disorder. They also supported the idea that white matter lesions may disrupt the neural circuits involved in mood regulation and thus contribute to the neuropathology of major depressive disorder.2. Our resting state fMRI study showed that abnormal brain activity of depression existed in resting state. The ReHo may be potentially helpful in understanding resting state of depression.