Instability of default mode network connectivity in major depression: a two-sample confirmation study

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Major depression exhibits altered static functional connectivity, particularly in the default mode network (DMN).
• Dynamic functional connectivity (dFC) offers a novel approach to study temporal fluctuations in brain networks, with limited application in affective disorders.

Purpose of the Study:

• To investigate the stability of functional connectivity within the DMN in individuals with major depression.
• To compare dFC stability between the medial prefrontal cortex (mPFC) and posterior cingulate cortex (PCC) in medication-free major depression patients and healthy controls.

Main Methods:

• Resting-state functional magnetic resonance imaging (fMRI) was used to assess functional connectivity stability between mPFC and PCC.
• Two independent samples, including a primary and a validation sample using multi-echo fMRI, were utilized to ensure replicability.

Main Results:

• Greater functional connectivity variability between the mPFC and PCC was observed in patients with major depression compared to healthy controls.
• These findings were consistently demonstrated across both independent samples, confirming reliability and robustness.

Conclusions:

• Alterations in the DMN in major depression involve reduced connectivity stability, not just changes in connectivity strength.
• These results highlight the importance of dynamic connectivity measures in understanding the neural underpinnings of major depression.