Multi-Site Statistical Mapping of Along-Tract Microstructural Abnormalities in Bipolar Disorder with Diffusion MRI...

Area of Science:

• Neuroimaging
• Neuroscience
• Psychiatry

Background:

• Bipolar disorder (BD) research seeks brain biomarkers for genetic and interventional studies.
• Previous diffusion MRI studies show white matter abnormalities in BD, but lack fine-scale spatial mapping along tracts.
• Large-scale, multisite studies are needed to enhance power and replicate findings in BD.

Approach:

• A multisite diffusion MRI study utilized BUndle ANalytics (BUAN) to analyze tractography data from 148 individuals with BD and 259 healthy controls across 6 sites.
• The approach involved extracting, mapping, and visualizing microstructural profiles along 3D fiber tract models.
• Site differences were modeled as random effects to investigate along-tract white matter (WM) microstructural differences between diagnostic groups.

Key Points:

• Group differences in white matter (WM) microstructural integrity were enhanced by integrating data from multiple sites.
• Bipolar disorder (BD) was associated with reduced mean fractional anisotropy (FA) in fronto-limbic, interhemispheric, and posterior pathways.
• Conversely, higher FA was observed in posterior bundles in individuals with BD compared to controls.

Conclusions:

• The BUAN pipeline effectively integrates tractography and anatomical information to capture unique along-tract effects in white matter (WM).
• This approach provides valuable insights into anatomical variations, potentially aiding in the classification of bipolar disorder (BD).
• The findings highlight the potential of fine-scale tract-based analysis for identifying biomarkers in BD.