Assessing the role of cingulate cortex in bipolar disorder: neuropathological, structural and functional imaging data

Area of Science:

• Neuroscience
• Psychiatry
• Neuroimaging

Background:

• Neuroanatomical models of bipolar disorder (BD) implicate the anterior cingulate cortex (ACC).
• Understanding ACC alterations is crucial for BD pathophysiology.
• Existing data on ACC neuroimaging and neuropathology in BD requires synthesis.

Purpose of the Study:

• To review available neuroimaging and neuropathological data on the ACC in BD.
• To synthesize findings on structural and functional changes in the ACC in BD patients.
• To address discrepancies and limitations in current research.

Main Methods:

• Systematic literature search of MEDLINE for English-written articles.
• Selection of studies reporting original experimental data on the cingulate gyrus in BD patients.
• Inclusion of studies with neuroimaging or neuropathological data (81 articles retained).

Main Results:

• Early-stage BD patients exhibit subgenual ACC (sgACC) volume changes.
• sgACC resting-state activity is state-dependent (increased in mania, decreased in depression).
• Deficient GABAergic activity in the ACC is documented; pharmacological treatment may normalize some changes.

Conclusions:

• Significant discrepancies exist in functional, structural, and neuropathological findings across studies.
• Methodological limitations and clinical heterogeneity of BD contribute to inconsistent results.
• The validity of ACC changes as trait or state markers for BD remains debatable.