Brain functional alterations in MDD patients with somatic symptoms: A resting-state fMRI study

It has been established that major depressive disorder (MDD) is accompanied by various somatic symptoms that are related to the clinical course and severity of depression. However, the mechanisms of somatic symptoms in MDD have rarely been studied. In this study, we sought to investigate the functional neurological changes in MDD patients with somatic symptoms based off the regional homogeneity (ReHo) and the amplitude of low-frequency fluctuation (ALFF).Study participants included 74 first-episode, drug naïve MDD patients as well as 70 healthy subjects (HCs). Patients diagnosed with MDD were separated into two groups based on the presence (n=50) or absence (n=24) of somatic symptoms. Functional images were obtained and analyzed. Alterations in ReHo/ALFF and the severity of clinical symptoms were investigated using correlation analysis.More severe depressive symptoms were observed in the somatic depression group than that of the pure depression group (P< 0.001). Furthermore, there was a significant reduction in ReHo and ALFF in the bilateral precentral gyrus, bilateral postcentral gyrus, and left paracentral gyrus in the somatic MDD group as compared to the pure depression group (GRF correction, voxel-P< 0.001, cluster-P < 0.01). Pearson correlation analysis revealed a negative correlation between ReHo and ALFF values in these abnomal regions with the severity of somatic and depressive symptoms (P< 0.01).Somatic depression is more severe than pure depression. The ReHo and ALFF changes in the precentral gyrus, postcentral gyrus, and paracentral gyrus may serve a significant role in the pathophysiology of somatic symptoms in MDD.