a b s t r a c t
Age-related differences in white-matter (WM) integrity are substantial, but it is unknown whether
between-subject variability in WM integrity influences the capacity for cognitive improvement. We
investigated the effects of memory training related to active and passive control conditions in older
adults and tested whether WM integrity at baseline was predictive of training benefits.We hypothesized
that (1) memory improvement would be restricted to the training group, (2) widespread areas would
show greater mean diffusivity (MD) and lower fractional anisotropy in older adults relative to young
adults, and (3) within these areas, variability in WM microstructure in the older group would be
predictive of training gains. The results showed that only the group receiving training improved their
memory. Significant age differences in MD and fractional anisotropy were found in widespread areas.
Within these areas, voxelwise analyses showed a negative relationship between MD and memory
improvement in 3 clusters, indicating that WM integrity could serve as a marker for the ability to adapt
in response to cognitive challenges in aging.