Cognitive reserve moderates the relationship between neuropsychological performance and white matter fiber bundle length in healthy older adults
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Recent work using novel neuroimaging methods has revealed shorter white matter fiber bundle length (FBL) in older compared to younger adults. Shorter FBL also corresponds to poorer performance on cognitive measures sensitive to advanced age. However, it is unclear if individual factors such as cognitive reserve (CR) effectively moderate the relationship between FBL and cognitive performance. This study examined CR as a potential moderator of cognitive performance and brain integrity as defined by FBL. Sixty-three healthy adults underwent neuropsychological evaluation and 3T brain magnetic resonance imaging. Cognitive performance was measured using the Repeatable Battery of Assessment of Neuropsychological Status (RBANS). FBL was quantified from tractography tracings of white matter fiber bundles, derived from the diffusion tensor imaging. CR was determined by estimated premorbid IQ. Analyses revealed that lower scores on the RBANS were associated with shorter whole brain FBL (p = 0.04) and lower CR (p = 0.01) CR moderated the relationship between whole brain FBL and RBANS score (p < 0.01). Tract-specific analyses revealed that CR also moderated the association between FBL in the hippocampal segment of the cingulum and RBANS performance (p = 0.03). These results demonstrate that lower cognitive performance on the RBANS is more common with low CR and short FBL. On the contrary, when individuals have high CR, the relationship between FBL and cognitive performance is attenuated. Overall, CR protects older adults against lower cognitive performance despite age-associated reductions in FBL.
KeywordsCognition Aging Neuropsychological assessment Diffusion tensor imaging RBANS
Supported by National Institutes of Health/National Institute of Neurological Disorders and Stroke grant number R01 NS052470 and R01 NS039538, National Institutes of Health/National Institute of Mental Health grant R21 MH090494 and R21 MH105822. Recruitment database searches were supported in part by National Institutes of Health/National Center for Research Resources grant UL1 TR000448.
Compliance with ethical standards
Conflict of interest
Laurie M Baker, David H Laidlaw, Ryan Cabeen, Erbil Akbudak, Thomas E Conturo, Stephen Correria, David F Tate, Jodi M Heaps-Woodruff, Matthew R Brier, Jacob Bolzenius, Lauren E Salminen, Elizabeth M Lane, Amanda R McMichael, and Robert H Paul declare no conflicts of interest.
All procedures followed were in accordance with the ethnical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinksi Declaration of 1975, and the applicable revisions at the time of the investigation. Informed consent was obtained from all patients for being included in the study.
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