Cardiorespiratory Fitness and White Matter Neuronal Fiber Integrity in Mild Cognitive Impairment

Article type: Research Article

Authors: Ding, Kan^{a; 1} | Tarumi, Takashi^{a; e; 1} | Zhu, David C.^g | Tseng, Benjamin Y.^{b; e} | Thomas, Binu P.^c | Turner, Marcel^e | Repshas, Justin^e | Kerwin, Diana R.^f | Womack, Kyle B.^{a; d} | Lu, Hanzhang^c | Cullum, C. Munro^{a; d} | Zhang, Rong^{a; b; e; *}

Affiliations: [a] Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX, USA | [b] Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA | [c] Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA | [d] Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA | [e] Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA | [f] Texas Alzheimer’s and Memory Disorders, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA | [g] Departments of Radiology and Psychology, and Cognitive Imaging Research Center, Michigan State University, EastLansing, MI, USA

Correspondence: [*] Correspondence to: Rong Zhang, PhD, 7232 Greenville Avenue, Dallas, TX 75231, USA. Tel.: +1 214 345 8843; Fax: +1 214 345 4618; E-mail: RongZhang@TexasHealth.org.

Note: [1] These authors contributed equally to this work.

Abstract: Background:Mounting evidence showed the self-reported levels of physical activity are positively associated with white matter (WM) integrity and cognitive performance in normal adults and patients with mild cognitive impairment (MCI). However, the objective measure of cardiorespiratory fitness (CRF) was not used in these studies. Objective:To determine the associations of CRF measured by maximal oxygen uptake (VO2max) with WM fiber integrity and neurocognitive performance in older adults with MCI. Methods:Eighty-one participants (age = 65±7 years, 43 women), including 26 cognitively normal older adults and 55 amnestic MCI patients, underwent VO2max test to measure CRF, diffusion tensor imaging (DTI) to assess WM fiber integrity, and neurocognitive assessment focused on memory and executive function. DTI data were analyzed by the tract-based spatial statistics and region-of-interest approach. Results:Cognitively normal older adults and MCI patients were not different in global WM fiber integrity and VO2max. VO2max was associated positively with DTI metrics of fractional anisotropy in ∼54% WM fiber tracts, and negatively with mean and radial diffusivities in ∼46% and ∼56% of the WM fiber tracts. The associations of VO2max with DTI metrics remained statistically significant after adjustment of age, sex, body mass index, WM lesion burden, and MCI status. The DTI metrics obtained from the area that correlated to VO2max were associated with executive function performance in MCI patients. Conclusions:Higher levels of CRF are associated with better WM fiber integrity, which in turn is correlated with better executive function performance in MCI patients.

Keywords: Cardiorespiratory fitness, executive function, mild cognitive impairment, white matter

DOI: 10.3233/JAD-170415

Journal: Journal of Alzheimer's Disease, vol. 61, no. 2, pp. 729-739, 2018