Frontal white matter alterations are associated with executive cognitive function in euthymic bipolar patients

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Psychiatry

Background:

• Bipolar disorder (BD) is frequently linked to executive cognitive dysfunction.
• The precise biological basis for these cognitive deficits in BD remains unclear.
• Evidence suggests white matter (WM) structural integrity is compromised in BD patients.

Purpose of the Study:

• To investigate the relationship between WM structural abnormalities and cognitive function in euthymic middle-aged BD patients.
• To compare WM integrity and cognitive performance between BD patients and healthy controls.

Main Methods:

• Diffusion tensor imaging (DTI) was employed for both voxelwise (TBSS) and region-of-interest (ROI) analyses.
• Key diffusion indices, including fractional anisotropy (FA), radial (DR), axial (DA), and mean diffusivities (MD), were compared.
• Thirty euthymic BD patients and 32 healthy controls participated in the study.

Main Results:

• BD patients exhibited increased mean diffusivity in the fornix, anterior thalamic radiation, splenium, and truncus of the corpus callosum compared to controls.
• These observed diffusion changes significantly correlated with diminished performance on executive function tasks in BD patients.
• Specific WM tracts implicated include fronto-limbic pathways.

Conclusions:

• A direct association exists between executive cognitive function and the microstructural integrity of fronto-limbic WM tracts in remitted BD patients.
• These findings support the hypothesis of underlying neuronal disruption contributing to residual symptoms in BD.
• The study highlights the neurobiological underpinnings of cognitive deficits in bipolar disorder.