Cardiorespiratory fitness and white matter integrity in Alzheimer’s disease

• Published in: Brain imaging and behavior Vol. 10; no. 3; pp. 660 - 668
• Main Authors: Perea, R. D., Vidoni, E. D., Morris, J. K., Graves, R. S., Burns, J. M., Honea, R. A.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-09-2016; Springer Nature B.V
• Subjects: Aged; Alzheimer Disease - diagnostic imaging; Alzheimer Disease - physiopathology; Alzheimer's disease; Biomedical and Life Sciences; Biomedicine; Cardiorespiratory Fitness; Cross-Sectional Studies; Diffusion Tensor Imaging; Exercise Test; Female; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Neuropsychology; Neuroradiology; Neurosciences; Original Research; Psychiatry; Sedentary Behavior; White Matter - diagnostic imaging; Neuroimaging; Diffusion imaging; Exercise; Alzheimer’s disease; Fitness
• ISSN: 1931-7557; 1931-7565
• DOI: 10.1007/s11682-015-9431-3

The objective of this study was to investigate the relationship between cardiorespiratory (CR) fitness and the brain’s white matter tract integrity using diffusion tensor imaging (DTI) in the Alzheimer’s disease (AD) population. We recruited older adults in the early stages of AD (
n
 = 37; CDR = 0.5 and 1) and collected cross-sectional fitness and diffusion imaging data. We examined the association between CR fitness (peak oxygen consumption [VO
2
peak]) and fractional anisotropy (FA) in AD-related white matter tracts using two processing methodologies: a tract-of-interest approach and tract-based spatial statistic (TBSS). Subsequent diffusivity metrics (radial diffusivity [RD], mean diffusivity [MD], and axial diffusivity [A × D]) were also correlated with VO
2
peak. The tract-of-interest approach showed that higher VO
2
peak was associated with preserved white matter integrity as measured by increased FA in the right inferior fronto-occipital fasciculus (
p
 = 0.035,
r
 = 0.36). We did not find a significant correlation using TBSS, though there was a trend for a positive association between white matter integrity and higher VO
2
peak measures (
p
 < 0.01 uncorrected). Our findings indicate that higher CR fitness levels in early AD participants may be related to preserved white matter integrity. However to draw stronger conclusions, further study on the relationship between fitness and white matter deterioration in AD is necessary.