Short superficial white matter and aging: A longitudinal multi-site study of 1293 subjects and 2711 sessions
Kurt G. Schilling,
Derek Archer,
Fang-Cheng Yeh,
Francois Rheault,
Leon Y. Cai,
Andrea Shafer,
Susan M. Resnick,
Timothy Hohman,
Angela Jefferson,
Adam W. Anderson,
Hakmook Kang,
Bennett A. Landman
Affiliations
Kurt G. Schilling
Department of Radiology & Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Corresponding author.
Derek Archer
Vanderbilt Memory and Alzheimer’s Center, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA; Vanderbilt Genetics Institute, Vanderbilt University School of Medicine, Nashville, TN, USA
Fang-Cheng Yeh
Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
Francois Rheault
Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN, USA
Leon Y. Cai
Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN, USA
Andrea Shafer
Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
Susan M. Resnick
Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
Timothy Hohman
Vanderbilt Memory and Alzheimer’s Center, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA; Vanderbilt Genetics Institute, Vanderbilt University School of Medicine, Nashville, TN, USA
Angela Jefferson
Vanderbilt Memory and Alzheimer’s Center, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
Adam W. Anderson
Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
Hakmook Kang
Department of Biostatistics, Vanderbilt University, Nashville, TN, USA
Bennett A. Landman
Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN, USA
It is estimated that short association fibers running immediately beneath the cortex may make up as much as 60 % of the total white matter volume. However, these have been understudied relative to the long-range association, projection, and commissural fibers of the brain. This is largely because of limitations of diffusion MRI fiber tractography, which is the primary methodology used to non-invasively study the white matter connections. Inspired by recent anatomical considerations and methodological improvements in superficial white matter (SWM) tractography, we aim to characterize changes in these fiber systems in cognitively normal aging, which provide insight into the biological foundation of age-related cognitive changes, and a better understanding of how age-related pathology differs from healthy aging. To do this, we used three large, longitudinal and cross-sectional datasets (N = 1293 subjects, 2711 sessions) to quantify microstructural features and length/volume features of several SWM systems. We find that axial, radial, and mean diffusivities show positive associations with age, while fractional anisotropy has negative associations with age in SWM throughout the entire brain. These associations were most pronounced in the frontal, temporal, and temporoparietal regions. Moreover, measures of SWM volume and length decrease with age in a heterogenous manner across the brain, with different rates of change in inter-gyri and intra-gyri SWM, and at slower rates than well-studied long-range white matter pathways. These features, and their variations with age, provide the background for characterizing normal aging, and, in combination with larger association pathways and gray matter microstructural features, may provide insight into fundamental mechanisms associated with aging and cognition.
