Altered functional connectivity density in major depressive disorder at rest

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Major depressive disorder (MDD) is associated with abnormal resting-state brain connectivity.
• Current research often uses predefined networks or seed regions, potentially introducing bias.
• A hypothesis-free approach is needed to fully explore functional alterations in MDD.

Purpose of the Study:

• To investigate functional brain connectivity alterations in MDD using a hypothesis-free method.
• To identify specific brain regions with abnormal functional connectivity density (FCD) in MDD patients.
• To compare findings with traditional network-based analyses.

Main Methods:

• Applied functional connectivity density (FCD) analysis to whole-brain resting-state fMRI data.
• Compared FCD in 21 MDD patients and 23 healthy controls.
• Correlated FCD findings with independent component analysis (ICA) of salience and visual networks.

Main Results:

• MDD patients exhibited reduced FCD in the mid-cingulate cortex (MCC) and increased FCD in the occipital cortex (OCC).
• MCC alterations involved reduced connectivity to the left amygdala.
• OCC changes included increased connectivity to the right supplementary motor area.

Conclusions:

• Abnormal functional connectivity in MDD is evident in the cingulate and occipital cortex, detectable via global FCD.
• These findings align with structural and metabolic evidence in MDD.
• Hypothesis-free FCD analysis reveals connectivity changes missed by traditional network or seed-based methods, highlighting its importance in understanding MDD pathophysiology.