Gray Matter Volume Abnormalities in the Reward System in First-Episode Patients with Major Depressive Disorder

In current time, the crowd of depression has increased rapidly across colleges and universities in China. They often suffer anhedonia, social failure, drug abuse and so on. The recent reports points out that the brain reward system showed damaged in patients with depression, so the identification of the dysfunction in the brain reward system is really crucial. By analyzing brain magnetic resonance imaging (MRI) data, this article aimed to identify the gray matter volume (GMV) abnormalities in brain reward system between first-episode medication-naive patients with major depressive disorder (MDD) and healthy controls (HCs). 14 medication-naive participants with MDD aged 19-24 years (6 males, 8 females) and 18 healthy controls aged 19-24 years (9 males, 9 females) were recruited. We used voxel-based morphometry (VBM) to analyze brain imaging data. Then, two sample t-test was applied to detect GM abnormalities in MDD compared to HCs. This study found that MDD showed increased gray matter volume (GMV) in putamen, precuneus and amygdala in right hemisphere compared to HCs. Furthermore, MDD showed decreased GMV in left rectus, right orbital medial prefrontal cortex (omPFC), left superior temporal gyrus (STG) and left insula compared to HCs. However, no significant changes were found in caudate nucleus. These experimental results show that the depression disorder causes extensive damage in reward system and subcortical brain regions, and the alterations in the rectus, the omPFC, STG, precuneus and amygdala, may be characters of MDD in first episode.