Altered Global Signal Topography in Major Depressive Disorder With and Without Anxiety

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Major depressive disorder (MDD) involves altered global signal (GS) topography across brain networks.
• Understanding GS distribution in MDD patients with comorbid anxiety is crucial but poorly understood.
• Previous studies show potential of global brain activity measures in differentiating MDD from healthy controls (HCs).

Purpose of the Study:

• To investigate anxiety-related alterations in global signal (GS) topography in major depressive disorder (MDD).
• To explore associations between altered GS topography and clinical symptoms in MDD patients.
• To differentiate GS topography patterns in MDD with anxiety versus MDD without anxiety and HCs.

Main Methods:

• Utilized resting-state functional magnetic resonance imaging (fMRI) and T1-weighted imaging data from 334 MDD patients with anxiety, 145 MDD patients without anxiety, and 307 HCs.
• Computed global signal topography using global signal correlation (GSCORR).
• Assessed structural-functional interaction (SFI) by correlating gray matter volume with GS.

Main Results:

• No significant whole-brain or network-level GS topography differences were found among the three groups.
• Anxious MDD patients showed decreased GSCORR in the right precentral gyrus, insula, and posterior parieto-occipital cortex compared to HCs.
• SFI revealed anxiety-related alterations in the sensorimotor network, precuneus, putamen, and middle temporal gyrus.

Conclusions:

• Findings suggest an abnormal topographic shift in global brain activity in MDD patients with anxiety.
• Altered GSCORR in specific brain regions correlates with anxiety and depression symptoms.
• This study provides new insights into brain dysfunction associated with MDD and comorbid anxiety.