Brain microstructure alterations in bipolar disorder subtypes revealed by diffusion kurtosis imaging.

Area of Science:

• Neuroimaging
• Neuroscience
• Radiology

Background:

• Bipolar disorder (BD) is linked to white matter (WM) microstructural alterations.
• Diffusion Tensor Imaging (DTI) has been utilized, but Diffusion Kurtosis Imaging (DKI) remains underexplored in BD subtypes.

Purpose of the Study:

• To compare DTI and DKI metrics in the brain's WM for individuals with Bipolar I (BD-I) and Bipolar II (BD-II) disorders versus healthy controls (HC).
• To investigate correlations between diffusion metrics and clinical scores in BD.
• To assess DKI's sensitivity in detecting WM alterations in BD subtypes.

Main Methods:

• Cross-sectional study involving 40 BD patients (BD-I and BD-II) and 42 HC.
• Tract-based spatial statistics (TBSS) applied to DTI and DKI metrics.
• Analysis of fractional anisotropy (FA) and kurtosis values.

Main Results:

• BD-I patients exhibited lower fractional anisotropy and kurtosis values compared to BD-II and HC groups.
• WM disruption was more severe in BD-I than BD-II.
• DKI analyses revealed a larger spatial extent of significant effects across BD subtypes compared to DTI.

Conclusions:

• DKI enhances sensitivity to WM microstructural changes in bipolar disorder.
• DKI offers valuable insights into the distinct biological underpinnings of BD-I and BD-II.
• Significant microstructural WM differences exist between BD subtypes.