White matter microstructural integrity and cognitive function in a general elderly population.

Area of Science:

• Neuroimaging
• Gerontology
• Cognitive Neuroscience

Background:

• Macrostructural white matter changes (atrophy, lesions) are linked to cognitive decline in the elderly.
• These macrostructural changes do not fully explain cognitive variability in older populations.
• Microstructural white matter integrity may offer additional insights into cognitive function.

Purpose of the Study:

• To investigate the relationship between white matter integrity and cognition in a general elderly population.
• To utilize diffusion tensor imaging (DTI) to assess white matter integrity.
• To account for macrostructural white matter changes in the analysis.

Main Methods:

• Cross-sectional, population-based study in the Netherlands.
• Included 860 community-dwelling individuals over 60, free of dementia.
• Employed multisequence MRI with DTI, measuring fractional anisotropy and diffusivities in white matter lesions and normal-appearing white matter, alongside extensive neuropsychological testing.

Main Results:

• Higher mean diffusivity and directional diffusivities in white matter lesions and normal-appearing white matter correlated with poorer performance in information processing speed and global cognition.
• Diffusivity in white matter lesions was associated with memory, and in normal-appearing white matter, with executive function.
• Lower mean fractional anisotropy in both white matter lesions and normal-appearing white matter was linked to slower information processing speed and motor speed.

Conclusions:

• White matter microstructural integrity, in both lesions and normal-appearing areas, is associated with cognitive function.
• These associations persist irrespective of white matter atrophy and lesion volume.
• Assessing white matter integrity provides added value beyond macrostructural analysis for understanding cognitive function in aging.