Cognitive correlates of cerebral white matter lesions and water diffusion tensor parameters in community-dwelling...

Area of Science:

• Neuroimaging
• Gerontology
• Cognitive Neuroscience

Background:

• The biological underpinnings of cognitive aging remain unclear.
• Disruption of white matter tracts may contribute to cognitive decline in older adults.
• White matter lesions (WML) and diffusion tensor MRI (DT-MRI) parameters like mean diffusivity (MD) and fractional anisotropy (FA) may indicate white matter integrity changes.

Purpose of the Study:

• To investigate the relationship between WML load, DT-MRI parameters, and cognitive function in a cohort of elderly individuals.
• To assess subtle changes in white matter integrity using DT-MRI in relation to cognitive aging.
• To identify specific cognitive domains affected by age-related white matter changes.

Main Methods:

• 105 community-dwelling elderly volunteers (mean age 78.4 years) underwent MRI and neuropsychological testing.
• White matter lesion (WML) load was assessed, and mean diffusivity (MD) and fractional anisotropy (FA) were measured in normal-appearing white matter regions.
• Regions of interest included frontal white matter, occipital white matter, and centrum semiovale.

Main Results:

• DT-MRI parameters (MD and FA) varied significantly across brain regions and showed age-related changes (MD increased with age, negatively correlated with FA).
• A trend indicated increased WML load correlated with poorer cognitive function, significantly for the Mini-Mental State Examination.
• Mean diffusivity (MD) generally correlated negatively with cognitive scores, while FA correlated positively, with MD showing a more consistent pattern, especially for verbal fluency (executive function).

Conclusions:

• DT-MRI parameters, particularly mean diffusivity (MD), are sensitive indicators of early ultrastructural changes associated with cognitive aging.
• Executive function appears to be the cognitive domain most vulnerable to age-related decline in white matter tract integrity.
• These findings highlight the utility of DT-MRI in understanding the neurobiological basis of cognitive aging.