White Matter Microstructural Changes and Episodic Memory Disturbances in Late-Onset Bipolar Disorder

Area of Science:

• Neuroimaging
• Neurology
• Psychiatry

Background:

• Bipolar disorder (BD) is linked to network disruptions.
• Understanding white matter (WM) tract connectivity in early-onset (EOD) versus late-onset bipolar disorder (LOD) is limited.

Purpose of the Study:

• To investigate differences in WM microstructure and cognitive function between EOD and LOD.
• To explore the relationship between disease onset and neurobiological changes in BD.

Main Methods:

• Diffusion tensor imaging (DTI) and volumetric analysis were used.
• Participants included EOD (n=16), LOD (n=14), and healthy controls (n=32).
• Cognitive and behavioral assessments were performed.

Main Results:

• LOD patients exhibited lower fractional anisotropy (FA) in right-hemisphere WM tracts compared to EOD and controls.
• Specific affected tracts in LOD included the anterior thalamic radiation, fornix, and corpus callosum splenium.
• LOD patients demonstrated poorer episodic memory performance than EOD patients.

Conclusions:

• LOD is associated with more widespread WM microstructural changes and impaired episodic memory than EOD.
• These findings suggest WM integrity alterations may be linked to later BD onset through mechanisms other than neuroprogression.
• Further replication in larger, prospective studies is warranted.