Objective: White matter (WM) microstructural changes are
increasingly recognized as a mechanism of age-related cognitive differences.
This study examined the associations between patterns of WM microstructure and
cognitive performance on the University of California, San Francisco (UCSF)
Brain Health Assessment (BHA) subtests of memory (Favorites), executive
functions and speed (Match), and visuospatial skills (Line Orientation) within a
sample of older adults. Method: Fractional anisotropy (FA) in WM
tracts and BHA performance were examined in 84 older adults diagnosed as
neurologically healthy (47), with mild cognitive impairment (19), or with
dementia (18). The relationships between FA and subtest performances were
evaluated using regression analyses. We then explored whether regional WM
predicted performance after accounting for variance explained by global FA.
Results: Memory performance was associated with FA of the
fornix and the superior cerebellar peduncle; and executive functions and speed,
with the body of the corpus callosum. The fornix–memory association and
the corpus callosum–executive association remained significant after
accounting for global FA. Neither tract-based nor global FA was associated with
visuospatial performance. Conclusions: Memory and executive
functions are associated with different patterns of WM diffusivity. Findings add
insight into WM alterations underlying age- and disease-related cognitive
decline.