Aberrant connectivity within the default mode network in first-episode, treatment-naïve major depressive disorder

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Major depressive disorder (MDD) is linked to default mode network (DMN) dysfunction.
• Altered connectivity in posterior cingulate cortex (PCC) and medial prefrontal cortex (mPFC) is noted in MDD.
• Internal functional connectivity within the DMN in early-stage MDD requires further clarification.

Purpose of the Study:

• To investigate the internal functional connectivity patterns within the DMN in first-episode, treatment-naïve major depressive disorder (MDD) patients.
• To identify specific alterations in DMN connectivity at the initial onset of MDD.
• To explore the relationship between DMN connectivity abnormalities and clinical severity in MDD.

Main Methods:

• Resting-state functional magnetic resonance imaging (fMRI) was employed.
• 38 first-episode, treatment-naïve MDD patients and 38 matched healthy controls participated.
• Seed-based analysis defined the DMN, followed by region-to-region connectivity analysis and Spearman correlation with clinical scores.

Main Results:

• Decreased DMN connectivity was found between PCC and dmPFC, PCC and the right angular gyrus, and left thalamus and cerebellar tonsil.
• No significant increases in connectivity were observed within the DMN.
• A marginal negative correlation was found between left thalamus-cerebellar tonsil connectivity and Hamilton Depression Rating Scale (HDRS) scores.

Conclusions:

• Internal functional connectivity within the DMN, rather than overall DMN connectivity, may be key to understanding MDD's pathological mechanisms.
• Specific regions within the DMN might possess distinct functional roles in MDD.
• These findings provide insights into the neural underpinnings of early-stage MDD.