Abstract
Abnormal functional connectivity (FC) at rest has been identified in clinical depressive disorder. However, very few studies have been conducted to understand the underlying neural substrates of subclinical depression. The newly proposed centrality analysis approach has been increasingly used to explore the large-scale brain network of mental diseases. This study aimed to identify the degree centrality (DC) alteration of the brain network in subclinical depressive subjects. Thirty-seven candidates with subclinical depression and 34 well-matched healthy controls (HCs) were recruited from the same sample of college students. All subjects underwent a resting-state fMRI (rs-fMRI) scan to assess the DC of the whole brain. Compared with controls, subclinical depressive subjects displayed decreased DC in the right parahippocampal gyrus (PHG), left PHG/amygdala, and left caudate and elevated DC in the right posterior parietal lobule (PPL), left inferior frontal gyrus (IFG) and left middle frontal gyrus (MFG). In addition, by using receiver operating characteristic (ROC) analysis, we determined that the DC values in the regions with altered FC between the two groups can be used to differentiate subclinical depressive subjects from HCs. We suggest that decreased DC in subcortical and increased DC in cortical regions might be the neural substrates of subclinical depression.
Highlights
Subclinical depression, defined as relevant depressive symptoms without meeting the full criteria of a clinical depressive disorder, has been identified as a health problem among college students worldwide (Mikolajczyk et al, 2008a)
These studies may partially indicate neural substrates related to structural alterations of subthreshold depression; the changes in functional connectivity (FC) between these brain regions with structural alterations remain unknown
Age or education level were found between subclinical depressive subjects and healthy controls (HCs) (P > 0.05)
Summary
Subclinical depression, defined as relevant depressive symptoms without meeting the full criteria of a clinical depressive disorder, has been identified as a health problem among college students worldwide (Mikolajczyk et al, 2008a). A voxel-based morphometry (VBM) study revealed decreased gray matter volume in the right parahippocampal gyrus (PHG) in elderly individuals with subthreshold depression (Zhou et al, 2016); in addition, compared with controls, smaller gray matter volume in the frontolimbic circuits including the prefrontal, ACC, caudates and cingulum was found in adolescents with subthreshold depression (Vulser et al, 2015). These studies may partially indicate neural substrates related to structural alterations of subthreshold depression; the changes in FC between these brain regions with structural alterations remain unknown
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