Cognitive functions in multiple sclerosis: impact of gray matter integrity

Area of Science:

• Neuroimaging
• Neurology
• Cognitive Science

Background:

• Multiple sclerosis (MS) is a demyelinating disease affecting the central nervous system.
• Cognitive impairment is a common and disabling symptom in MS patients.
• The distinct contributions of gray matter (GM) and white matter (WM) integrity to cognitive deficits in MS require further elucidation.

Purpose of the Study:

• To investigate the impact of GM integrity on cognitive performance in MS.
• To examine the relationship between GM integrity, WM integrity, and lesion load in MS.
• To identify neuroimaging markers associated with cognitive function in MS.

Main Methods:

• Voxel-based analysis of diffusion tensor imaging (DTI) in GM and tract-based spatial statistics (TBSS) in WM were performed on 67 MS patients and 26 controls.
• Lesion probability mapping (LPM) was used to correlate lesion load with cognitive performance.
• Multiple linear regression analyses identified imaging measures associated with cognitive scores.

Main Results:

• MS patients exhibited abnormal DTI indices in multiple GM regions and WM tracts compared to controls.
• Impaired DTI indices in specific GM regions correlated with deficits in distinct cognitive functions.
• While combined GM and WM DTI and lesion volume explained 36-51% of memory and attention variance, regional GM DTI alone accounted for less than 5%.

Conclusions:

• Integrity of specific GM and WM networks critically influences cognitive performance in MS.
• GM integrity, as assessed by DTI, provides only a minor additional predictive value for cognitive functioning beyond WM integrity.