Abnormal cortical-striatal-thalamic-cortical circuit centered on the thalamus in MDD patients with somatic symptoms: Evidence from the REST-meta-MDD project

Somatic symptoms are common comorbidities of major depressive disorder (MDD), and negatively impact the course and severity of the disease. In order to enrich the understanding of the pathological mechanism and clarify the neurobiological basis of somatic symptoms in depression, we attempted to explore the changes of brain structure and function in a large sample between depression with and without somatic symptoms.Structure magnetic resonance imaging (MRI) data were collected from 342 patients with somatic symptoms (SD), 208 patients without somatic symptoms (NSD), and 510 healthy controls (HCs) based on the REST-meta-MDD project. We analyzed the whole brain VBM maps of the three groups, and combined with weight degree centrality (DC) index, we investigated whether the brain regions with gray matter volume (GMV) and gray matter density (GMD) abnormalities in MDD patients with somatic symptoms had corresponding brain functional abnormalities.Between depression with and without somatic symptoms, we found that there are extensive GMV and GMD differences involving cortical regions such as the temporal lobe, occipital lobe, and insula, as well as subcortical brain regions such as thalamus and striatum. The comparison results of weight DC signals of GMV and GMD abnormal clusters between the SD and NSD groups were basically consistent with the GMV and GMD abnormal clusters.The results indicate that the structure and function of cortical-striatal-thalamic-cortical (CSTC) circuit centered on the thalamus were abnormal in MDD patients with somatic symptoms. This may be the neurobiological basis of somatic symptoms in MDD.