Moderate Physical Activity is Associated with Cerebral Glucose Metabolism in Adults at Risk for Alzheimer’s Disease

Article type: Research Article

Authors: Dougherty, Ryan J.^{a; b} | Schultz, Stephanie A.^{b; c} | Kirby, Taylor K.^{b; c} | Boots, Elizabeth A.^{b; c} | Oh, Jennifer M.^{b; c} | Edwards, Dorothy^{a; b; d} | Gallagher, Catherine L.^{c; d; e} | Carlsson, Cynthia M.^{b; c; d} | Bendlin, Barbara B.^{b; c; d} | Asthana, Sanjay^{b; c; d} | Sager, Mark A.^{b; d} | Hermann, Bruce P.^{b; d} | Christian, Bradley T.^f | Johnson, Sterling C.^{b; c; d} | Cook, Dane B.^{a; g} | Okonkwo, Ozioma C.^{b; c; d; *}

Affiliations: [a] Department of Kinesiology, University of Wisconsin School of Education, Madison, WI, USA | [b] Wisconsin Alzheimer’s Disease Research Center | [c] Geriatric Research Education and Clinical Center, William S. Middleton Memorial VA Hospital, Madison, WI, USA | [d] Wisconsin Alzheimer’s Institute, Madison, WI, USA | [e] Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA | [f] Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA | [g] Research Service, William S. Middleton Memorial Veterans Hospital, Madison, WI, USA

Correspondence: [*] Correspondence to: Ozioma C. Okonkwo, Ph.D., Department of Medicine and Alzheimer’s Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA. Tel.: +1 608 265 4479; Fax: +1 608 265 3091; E-mail: ozioma@medicine.wisc.edu.

Abstract: The objective of this study was to investigate the relationship between accelerometer-measured physical activity (PA) and glucose metabolism in asymptomatic late-middle-aged adults. Ninety-three cognitively healthy late-middle-aged adults from the Wisconsin Registry for Alzheimer’s Prevention participated in this cross-sectional study. They underwent 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging and wore an accelerometer (ActiGraph GT3X+) to measure free-living PA. Accelerometer data yielded measures of light (LPA), moderate (MPA), and vigorous (VPA) intensity PA. FDG-PET images were scaled to the cerebellum and pons, and cerebral glucose metabolic rate was extracted from specific regions of interest (ROIs) known to be hypometabolic in AD, i.e., hippocampus, posterior cingulate, inferior temporal cortex, and angular gyrus. Regression analyses were utilized to examine the association between PA and glucose metabolism, while adjusting for potential confounds. There were associations between MPA and glucose metabolism in all ROIs examined. In contrast, LPA was not associated with glucose uptake in any ROI and VPA was only associated with hippocampal FDG uptake. Secondary analyses did not reveal associations between sedentary time and glucose metabolism in any of the ROIs. Exploratory voxel-wise analysis identified additional regions where MPA was significantly associated with glucose metabolism including the precuneus, supramarginal gyrus, amygdala, and middle frontal gyrus. These findings suggest that the intensity of PA is an important contributor to neuronal function in a late-middle-aged cohort, with MPA being the most salient. Prospective studies are necessary for fully elucidating the link between midlife engagement in PA and later life development of AD.

Keywords: Exercise, motor activity, neuroimaging, risk factor

DOI: 10.3233/JAD-161067

Journal: Journal of Alzheimer's Disease, vol. 58, no. 4, pp. 1089-1097, 2017