The global efficiency of brain white matter networks in the unipolar and bipolar depression patients and its relationship with the clinical features

Abstract

Objective To explore the differences of the nodal global efficiency (GE) of brain white matter networks in the unipolar depression (UD) patients, bipolar depression (BD) patients and healthy controls (HC) subjects. Method The diffusion tensor imaging data were obtained from 24 UD patients, 17 BD patients and 52 HC subjects. And the 17-Item Hamilton Depression Rating Scale (HAMD17) was used to evaluate the patients' condition. The whole cerebral cortex was divided into 90 regions by the automated anatomical labeling map. Fiber tracking was performed in the whole cerebral cortex of each subject to reconstruct white matter tracts using the fiber assignment by continuous tracking algorithm. And then the brain white matter networks were constructed using the complex network theory. The nodal GE of the brain networks of UD, BD and HC were compared by the one-way ANOVA and two sample t-tests, and then the correlations between the GE of the significant nodes and the clinical features of patients were explored by the Pearson correlation analysis. Result The significant nodes of the GE in there groups included the left anterior cingulate gyri (F=10.88, P=0.00) and right medial superior frontal gyrus (F=14.04, P=0.00), caudate nucleus (F=9.53, P=0.00), pallidum (F=12.83, P=0.00). The GE of UD was descendant significantly in the left medial superior frontal gyrus (0.44±0.03 vs. 0.47±0.03, t=-3.73, P=0.02), thalamus (0.44±0.04 vs. 0.47± 0.04, t=-3.29, P=0.03) and right medial superior frontal gyrus (0.40±0.02 vs. 0.42±0.03, t=-3.30, P=0.03), caudate nucleus (0.37 ± 0.01 vs. 0.39±0.02, t=- 5.07, P=0.00) when compared with HC. The GE of BD descent significantly in the left medial superior frontal gyrus (0.43±0.03 vs. 0.47±0.03, t=-4.81, P=0.00) and anterior cingulate gyri (0.47±0.03 vs. 0.51±0.03 , t=-4.34, P=0.00), however, increased significantly in the right caudate nucleus (0.47±0.03 vs. 0.45±0.02 , t=3.39, P=0.04) when compared with HC. The GE of BD was descendant significantly in the left anterior cingulate gyri (t=- 3.85, P=0.02), however, increased significantly in the right caudate nucleus (t=3.91, P=0.03) and pallidum (t=3.75, P=0.04) when compared with UD. Significant negative correlation was found between the GE of the left anterior cingulate gyri and the scores of anxiety/somatization factor (r=-0.43, P=0.04) in UD. And that were also found between the GE of the right medial superior frontal gyrus and the scores of anxiety/somatization (r=-0.49, P=0.04), and between the caudate nucleus and the retardation factor (r=- 0.56, P=0.02) in BD. However, significant positive correlation was found between the GE of the right medial superior frontal gyrus and the age of the onset (r= 0.51, P=0.04) in BD. Conclusion The efficiency of information integrating within the prefrontal-limbic and prefrontal-basal ganglia pathways may be decreased in UD. The efficiency of information integrating within the prefrontal-limbic pathway could be decreased, however, increased compensatorily within the prefrontal-basal ganglia pathway in BD. Key words: Depressive disorder; Bipolar disorder; Diffusion tensor imaging; Brain structural network; Global efficiency