Aerobic Exercise Improves Cognition for Older Adults with Glucose Intolerance, A Risk Factor for Alzheimer's Disease

Article type: Research Article

Authors: Baker, Laura D.^{a; b; *} | Frank, Laura L.^{a; b} | Foster-Schubert, Karen^{c; d} | Green, Pattie S^{c; e} | Wilkinson, Charles W.^{a; b} | McTiernan, Anne^{c; d} | Cholerton, Brenna A.^{a; b} | Plymate, Stephen R.^{b; c} | Fishel, Mark A.^{b; f} | Watson, G. Stennis^{a; b} | Duncan, Glen E.^g | Mehta, Pankaj D.^h | Craft, Suzanne^{a; b}

Affiliations: [a] Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Seattle, WA, USA | [b] Geriatric Research, Education, and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA | [c] Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA | [d] Cancer Prevention Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA, USA | [e] Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA | [f] Department of Neurology, University of Washington School of Medicine, Seattle, WA, USA | [g] School of Public Health, Department of Epidemiology, Nutritional Sciences Program, University of Washington, Seattle, WA, USA | [h] Department of Immunology, New York State Institute for Basic Research in Developmental Disabilities, New York, NY, USA

Correspondence: [*] Correspondence to: Laura D. Baker, PhD, VA Puget Sound Health Care System, GRECC A-182, 1660 S. Columbian Way, Seattle, WA 98108, USA. Tel.: +1 253 583 2900; Fax: +1 253 589 4073; E-mail: ldbaker@uw.edu.

Note: [] Handling Associate Editor: Jeffrey Burns

Abstract: Impaired glucose regulation is a defining characteristic of type 2 diabetes mellitus (T2DM) pathology and has been linked to increased risk of cognitive impairment and dementia. Although the benefits of aerobic exercise for physical health are well-documented, exercise effects on cognition have not been examined for older adults with poor glucose regulation associated with prediabetes and early T2DM. Using a randomized controlled design, twenty-eight adults (57–83 y old) meeting 2-h tolerance test criteria for glucose intolerance completed 6 months of aerobic exercise or stretching, which served as the control. The primary cognitive outcomes included measures of executive function (Trails B, Task Switching, Stroop, Self-ordered Pointing Test, and Verbal Fluency). Other outcomes included memory performance (Story Recall, List Learning), measures of cardiorespiratory fitness obtained via maximal-graded exercise treadmill test, glucose disposal during hyperinsulinemic-euglycemic clamp, body fat, and fasting plasma levels of insulin, cortisol, brain-derived neurotrophic factor, insulin-like growth factor-1, amyloid-β (Aβ40 and Aβ42). Six months of aerobic exercise improved executive function (MANCOVA, p = 0.04), cardiorespiratory fitness (MANOVA, p = 0.03), and insulin sensitivity (p = 0.05). Across all subjects, 6-month changes in cardiorespiratory fitness and insulin sensitivity were positively correlated (p = 0.01). For Aβ42, plasma levels tended to decrease for the aerobic group relative to controls (p = 0.07). The results of our study using rigorous controlled methodology suggest a cognition-enhancing effect of aerobic exercise for older glucose intolerant adults. Although replication in a larger sample is needed, our findings potentially have important therapeutic implications for a growing number of adults at increased risk of cognitive decline.

Keywords: Aerobic exercise, Alzheimer's disease, cognition, dementia, diabetes, executive function, glucose intolerance, prediabetes

DOI: 10.3233/JAD-2010-100768

Journal: Journal of Alzheimer's Disease, vol. 22, no. 2, pp. 569-579, 2010