Localized White Matter Tract Integrity Measured by Diffusion Tensor Imaging Is Altered in People with Mild Cognitive Impairment and Associated with Dual-Task and Single-Task Gait Speed
Affiliations: [a]
Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, London, Canada
| [b]
Department of Medicine, Division of Geriatric Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Canada
| [c] Gait and Brain Lab, Parkwood Institute, Lawson Health Research Institute, London, Canada
| [d]
Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Canada
| [e]
Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Canada
Correspondence:
[*]
Correspondence to: Robert Bartha, Imaging Research Laboratories, Robarts Research Institute, Schulich School of Medicine and Dentistry, The University of Western Ontario, 100 Perth Drive, London, ON, N6A 5K8, Canada. Tel.: +1 519 663 5777/Ext. 24039; Fax: +1 519 931 5224; E-mail: rob.bartha@imaging.robarts.ca.
Note: [1] Co-senior authors.
Abstract: Background:Altered white matter (WM) tract integrity may contribute to mild cognitive impairment (MCI) and gait abnormalities. Objective:The purpose of this study was to determine whether diffusion tensor imaging (DTI) metrics were altered in specific portions of WM tracts in people with MCI and to determine whether gait speed variations were associated with the specific DTI metric changes. Methods:DTI was acquired in 44 people with MCI and 40 cognitively normal elderly controls (CNCs). Fractional anisotropy (FA) and radial diffusivity (RD) were measured along 18 major brain WM tracts using probabilistic tractography. The average FA and RD along the tracts were compared between the groups using MANCOVA and post-hoc tests. The tracts with FA or RD differences between the groups were examined using an along-tract exploratory analysis to identify locations that differed between the groups. Associations between FA and RD in whole tracts and in the segments of the tracts that differed between the groups and usual/dual-task gait velocities and gross cognition were examined. Results:Lower FA and higher RD was observed in right cingulum-cingulate gyrus endings (rh.ccg) of the MCI group compared to the CNC group. These changes were localized to the posterior portions of the rh.ccg and correlated with gait velocities. Conclusion:Lower FA and higher RD in the posterior portion of the rh.ccg adjacent to the posterior cingulate suggests decreased microstructural integrity in the MCI group. The correlation of these metrics with gait velocities suggests an important role for this tract in maintaining normal cognitive-motor function.
Keywords: Diffusion tensor imaging, mild cognitive impairment, single-task and dual-task gait, white matter tracts, whole-brain tractography
