White Matter Correlates of Cognitive Capacity Studied With Diffusion Tensor Imaging: Implications for Cognitive Reserve

Cognitive reserve (CR) is a theoretical concept used to explain and study individual differences in cognitive symptom expression in neurological disease. In the absence of neurologic injury or demands on processing, compensatory and protective factors may be considered to represent cognitive capacity (CC), rather than cognitive reserve, per se. We studied the white matter structural correlates of CC in 51 young, healthy participants. White matter structural correlates were obtained from fractional anisotropy (FA) measures using diffusion tensor imaging (DTI). CC was represented by intelligence, reading ability, and years of education, commonly used measures for studying CR. CC was positively correlated with FA in the right posterior inferior longitudinal fasciculus. We observed gender differences in FA (males > females) and tested for gender differences in FA correlates of CC. However, the interaction between gender and CC for areas of FA was not significant. Our data indicate that in the healthy young brain, greater CC correlates with higher FA values in a focal area that does not significantly differ by gender.