Associations between anterior cingulate thickness, cingulum bundle microstructure, melancholia and depression...

Area of Science:

• Neuroimaging
• Psychiatry
• Neuroscience

Background:

• Major Depressive Disorder (MDD) involves structural and functional changes in the anterior cingulate cortex (ACC), impacting emotional, cognitive, and behavioral functions.
• The cingulum bundle (CB), a key white matter pathway, connects ACC segments and is implicated in MDD.
• This study investigates ACC cortical thickness and CB white matter microstructure in MDD, particularly the melancholic subtype.

Purpose of the Study:

• To examine cortical thickness in the rostral and caudal ACC in patients with MDD.
• To explore white matter microstructure integrity of the CB in MDD patients.
• To determine if ACC thickness and CB microstructure correlate with depression severity and subtype.

Main Methods:

• Structural and diffusion-weighted MRI scans were acquired from 54 MDD patients and 22 healthy controls.
• Cortical thickness of rostral and caudal ACC was computed.
• Manual tractography was used to reconstruct the bilateral CB, and fractional anisotropy (FA) was measured to assess white matter microstructure.

Main Results:

• No significant differences in ACC cortical thickness or CB FA were found between all MDD patients and healthy controls.
• Melancholic MDD patients exhibited reduced bilateral caudal ACC cortical thickness compared to non-melancholic patients and healthy controls.
• A significant association was observed between reduced bilateral CB FA and increased depression severity across all MDD patients.

Conclusions:

• Reduced cortical thickness of the caudal ACC is specifically associated with the melancholic subtype of depression.
• Cingulum bundle white matter microstructure, indicated by FA, may serve as a neuroimaging marker for depression severity in MDD.