Diagnostic value of structural, functional and effective connectivity in bipolar disorder

Area of Science:

• Neuroimaging
• Psychiatry
• Brain Connectivity

Background:

• Bipolar disorder (BD) diagnosis can be challenging.
• Neuroimaging techniques like fMRI offer potential biomarkers.
• Understanding brain connectivity differences is crucial.

Purpose of the Study:

• To systematically review functional magnetic resonance imaging (fMRI) studies on bipolar disorder (BD).
• To characterize structural, functional, and effective connectivity differences in BD patients compared to controls.
• To assess the potential of these connectivity patterns as diagnostic neuroimaging biomarkers.

Main Methods:

• Systematic literature search conducted in PUBMED and SCOPUS.
• Studies published since 2015 focusing on bipolar disorder connectivity were included.
• Followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Main Results:

• 60 studies were included: 20 on structural, 33 on functional, and 7 on effective connectivity.
• Abnormalities found in frontal gyrus, cingulate cortex, and emotion/reward networks in structural connectivity.
• Most common functional connectivity finding: cerebellum (vermis) to cerebrum. Alterations noted in salience, default mode, and executive control networks for effective connectivity.

Conclusions:

• Despite heterogeneity, distinct connectivity patterns emerge in bipolar disorder.
• Altered brain connectivity shows promise as a diagnostic biomarker for BD.
• Future research with larger samples and machine learning may accelerate diagnostic biomarker adoption.