Differences Between Unipolar And Bipolar Depressive Disorder: A Study Combing The Structural And Resting-state Functional MRI

Part I A Structural Magnetic Resonance Imaging Study on Unipolar and Bipolar Depressive Disorder PatientsObjective: To study the features of brain morphology and compare their similarities and differences of patients with unipolar and bipolar depressive disorder, we used high-resolution MRI and voxel-based morphometry(VBM8) to analyze grey matter differences in three groups.Methods: 51 unipolar depressive disorder patients, 29 bipolar depressive disorder patients and 31 healthy subjects participated in the structural MRI scan. Using voxel-based morphpmetry method, to analysis the s MRI data of unbipolar depressive group, bipolar depressive group and healthy control group. Volume differences between these three groups was evaluated using ANOVA test(p < 0.001(uncorrected), K>100) with covariant variables(education and TIV). Extracted the value of gray matter volume in significant differences of each group, then post hoc t-test were performed to exam the difference betwween each pair of groups(p < 0.05).Results: 1.There was 47 patients of unipolar depressive disorder, 28 patiens of bipolar depressive disorder and 29 healthy controls were sucessed in MRI analysis.2. Compared to healthy controls, patients of unipolar depressive disorder showed significant decreased grey matter volume in right posterior cerebellum, the bilateral superior temporal gyrus, the right insular, the right supramaginal gyrus and the left superior parietal lobule; Compared to healthy controls, patients of bipolar depressive disorder showed significant decreased grey matter volume in the right insular and increased grey matter volume in the right caudate nucleus; Compared to patients of bipolar depressive disorder, patients of unipolar depressive disorder showed significant decreased grey matter volume in the in right posterior cerebellum, the bilateral superior temporal gyrus, the right caudate nucleus, the right supramaginal gyrus and the left superior parietal lobule.3. The grey matter volume of the left superior parietal lobule was negative correlated with the number episode(r=-0.374,p=0.032).Conclusion: Altered grey matter volume was found in the right supramaginal gyrus, the bilateral superior temporal gyrus, the left superior parietal lobule and the right posterior cerebellum, might contribute to understanding the pathogenesis of major depressive disorder. Furthermore, altered grey matter volume of right caudate nucleus mabe related to the pathogenesis of bipolar depressive disorder. Besides, decreased grey matter volume in the right insular was found in patients of unipolar and bipolar depressive disorder, which indicates that it correlated with similar abnormal emotional and congnitive symptoms between unipolar and bipolar depressive disorder. Therefore, it’s meaningfull to go a little further studies of these brain regions will help us to further understand the pathophysiology of unipolar and bipolar depressive disorder.Part II Difference in Fractional Amplitude of Low-frequency Fluctuation between Unipolar and Bipolar Depressive Disorder PatientsObjective: Abnormal spontaneous neuronal activity is presumed to be a pathophysiological aspect of major depressive disorder(MDD). However, the underlying patterns of spontaneous neural activity have been poorly characterized and replicated to date. Blood oxygenation level-dependent(BOLD) functional magnetic resonance imaging studies in the rest state suggested some brains exist persistent signals of neural activity, which is spontaneous low-frequency fluctuation.In the present study, we aimed to explore the abnormal spontaneous neuronal activity between unipolar and bipolar depressive disorder patients, and its underlying mechanism.Methods: Fifty-one patients of unipolar depressive disorder and twenty-nine patients of bipolar depressive disorder measured by DSM-IV were scaned by resting state functional magnetic resonance imaging with thirty-one healthy controls. To explore the abnormal spontaneous neuronal activity in unipolar and bipolar depressive disorder patients, fractional amplitude of low frequency fluctuation(f ALFF) was utilized to analyze the data. The date was performed by Data Processing Assistant for Resting-State f MRI. Differences in f ALFF between the unipolar depressive disorder, bipolar depressive disorder and healthy control groups were evaluated using ANOVA(p < 0.001(uncorrected), K>10) with the REST software(http://restfmri.net/forum) with covariant variables(age, gender, education and TIV). Extracted the value of f ALFF in significant differences of each group, then post hoc t-test were performed to exam the difference between each pair of groups by using above-mentioned.Results: 1.There was 47 patients of unipolar depressive disorder, 28 patiens of bipolar depressive disorder and 29 healthy controls were sucessed in f ALFF analysis.2. Among patients of unipolar depressive disorder, patiens of bipolar depressive disorder and healthy control, the precuneus, lingual gruys, left middle temporal gyrus and left posterior cingutate exhibited significant difference f ALFF.3. Compared with healthy control groups, patients of unipolar depressive disorder showed significant decreased f ALFF value in the precuneus, left middle temporal gyrus and left posterior cingutate; Compared with patients of bipolar depressive disorder, patients of unipolar depressive disorder showed significant decreased f ALFF value in precuneus, left middle temporal gyrus and lingual gruys; compared with healthy control groups, patients of bipolar depressive disorder exhibited significant decreased f ALFF value left middle temporal gyrus and significant increased f ALFF value in lingual gruys.4. The value of f ALFF in significant difference brain showed no significant correlation with clinical variable(P <0.05).Conclusion: Significant decreased f ALFF value in left posterior cingutate of patients of unipolar and bipolar depressive disorder indicates similar depressive symptom between them. Conducting further research in default mode network may explain some of the clinical characteristics and disease accompanying patients of unipolar depressive disorder.