Decreased global signal topography in recurrent major depressive disorder

Motivation: Global signal (GS) distribution changes remain unclear in major depressive disorder (MDD). Goal(s): This study aimed to explore abnormal GS topography in MDD, and its underlying structural mechanism and relationship with clinical assessments. Approach: We used resting-state fMRI and T1-weighted data from the REST-meta-MDD consortium, and calculated the GS correlation (GSCORR) and gray matter volume (GMV). Results: We found decreased GS topography in sensorimotor networks in recurrent MDD, and altered GMV-GSCORR coupling in cingulo-opercular and frontoparietal/occipital networks in first-episode and recurrent MDD, respectively. The alterations of GS topography in temporal lobe and cerebellum correlated with HAMD/HAMA scores, which were partially mediated by GMV. Impact: Our findings demonstrated that first-episode and recurrent MDD showed different alterations in GS topography, which were associated with cortical GMV and clinical symptoms of patients, contributing to the understanding of relationship between global and local neuronal activities in MDD.