Abnormal static and dynamic regional homogeneity in adolescent major depressive disorder with somatic symptoms: a resting-state fMRI study.

Background: Somatic symptoms are common in adolescent major depressive disorder (MDD) and related to severity of depression and clinical outcomes. However, the neurological mechanism of somatic symptoms in adolescent MDD remains unknown. In this study, we aimed to explore the functional alterations of intrinsic brain local connectivity in adolescent MDD with somatic symptoms based on static and dynamic reginal homogeneity (ReHo).

Methods: This study included 50 first-episode, drug naïve adolescent MDD patients and 34 healthy controls (HCs) matched for age, gender and years of education. Patients were categorized into somatic depression (SD) group (n = 21) and non-somatic depression (NSD) group (n = 29) based on the presence of somatic symptoms or not. All participants underwent resting-state functional magnetic resonance imaging (rs-fMRI), and static and dynamic ReHo were calculated and compared among SD, NSD and HC groups. Correlation analysis was performed to evaluate the relationship between altered ReHo values and severity of clinical symptoms.

Results: Adolescent MDD patients with somatic symptoms showed higher total scores of the 17-items Hamilton Depression Scale (HAMD-17). Moreover, increased static ReHo in left inferior parietal gyrus (IPG), left superior parietal gyrus (SPG) and left triangular part of inferior frontal gyrus (IFGtriang) were observed in SD group compared with NSD group. The SD group also exhibited decreased dynamic ReHo in bilateral IPG, bilateral SPG, and left IFGtriang. Moreover, there were significant correlations between static and dynamic ReHo values in these abnormal brain regions and the weight factor scores of HAMD-17.

Conclusions: Our findings suggested that there may be abnormal patterns of functional local connectivity in SPG, IPG and IFGtriang in adolescent MDD patients with somatic symptoms, enriching the knowledge of neurological mechanism concerning somatic symptoms in adolescent MDD.