Macro- and micro-structural white matter differences correlate with cognitive performance in healthy aging

Area of Science:

• Neuroimaging
• Gerontology
• Cognitive Neuroscience

Background:

• White matter (WM) volume reductions and degradation are common with aging.
• The specific WM alterations linked to varying cognitive performance in older adults remain unclear.

Purpose of the Study:

• To identify and characterize macro and microstructural WM alterations differentiating older healthy individuals with contrasting cognitive profiles.
• To investigate how white matter signal abnormalities (WMSA) and diffusion tensor imaging (DTI) metrics relate to cognitive performance and aging.

Main Methods:

• Structural and diffusion MRI scans were acquired from older healthy individuals.
• WM volumes, WMSA volume (lesion burden), and DTI scalar maps were quantified.
• Neurocognitive tests assessed cognitive performance, categorizing participants into 'poor' and 'good' performers.

Main Results:

• Poor cognitive performers exhibited a steeper age-related increase in WMSA volume compared to good performers.
• Even after controlling for WMSA, poor performers showed lower fractional anisotropy (FA).
• Poor performers also displayed steeper age-related increases in radial and axial diffusivity.

Conclusions:

• Cognitive performance in older adults is associated with distinct WM characteristics.
• Poor cognitive performers exhibit indicators of accelerated WM aging, including increased lesion burden and microstructural changes.