A Study Of Brain Gray Matter Volume In Patients With Unipolar And Bipolar Depressive Disorder

Objective:We aimed to detect the difference in grey matter in both patients with unipolar and bipolar disorders and healthy controls, as well as in two disorders through the structural MRI data analysis. Further, we sought to explore similarities and differences and the liable neurophysiology in two disorders, throwing light on the differential diagnosis.Methods:A total of19patients with bipolar disorder,21patients with unipolar disorder and30well-matched healthy controls were recruited. All the subjects were measured by the clinical assessments and underwent the structural MRI scanning.Voxel-based morphometry analysis (VBM) was used to detect group differences in gray matter volume. One-way ANOVA and post-hoc analyses were performed on gray matter volume abstracted from different regions of the brain among groups. Correlations between the abnormality of grey matter and clinical characteristics were estimated.Results:There was no significant difference in scores on HAMD、 HAMA、 BPRS in patient groups, however, scores on WAIS of two patient groups were significantly lower than that of healthy controls. Patients with bipolar disorder showed decreased grey matter volume in many brain regions (p<0.005, cluster size>50), mainly including the right superior temporal gyrus, right insular lobe and right posterior cingutate, with increased grey matter volume in left cerebellar posterior lobe compared with healthy controls. Patients with unipolar disorder showed decreased grey matter volume in the right superior temporal gyrus and right insular lobe, with increased grey matter volume in left cerebellar anterior lobe compared with healthy controls. The grey matter volume of these three brain regions correlated with the WAIS performance significantly positive (p<0.05). The grey matter volume of posterior cingulate correlated with the score on HAMD significantly negative (p<0.05). Compared to patients with unipolar disorder, bipolar disorder patients had markedly decreased grey matter volume in the left posterior cingulate and left cerebellar anterior lobe.Conclusion:Superior temporal gyrus and insula may be involved with the development of depression. The unipolar and bipolar disorders may share some overlappings in pathophysiology to an extent, but bipolar disorder has more severe grey matter deficits than unipolar disorder. There is specificity of decreased posterior cingulate in bipolar disorder, the abnormality of which can contribute to the differentiation of unipolar and bipolar disorders in some degree.