Cognitive Effects of Aerobic Exercise for IGT Adults

The benefits of exercise on cognition have been demonstrated both in animals and humans. Exercise has salutary effects on glucoregulation and visceral adiposity, an important link for adults with impaired glucose tolerance (IGT) and type 2 diabetes mellitus (T2DM). Exercise also upregulates neurotrophic activity, an effect that serves to increase neuronal viability in the same brain regions that support complex cognitive functions affected by metabolic disease. In this proposed controlled intervention trial, the hypothesis is that aerobic exercise will have a beneficial effect on cognition and several biomarkers that index disease progression for older adults with IGT. 40 older subjects (age: >55 yrs) with IGT, confirmed by OGTT, will be randomized to an aerobic fitness or stretching program for 6 months. Cognitive measures and fasting blood samples will be obtained at baseline, month 3, and month 6. Cognitive tests will evaluate abilities affected by age and by significant glucoregulatory dysregulation. In addition, all subjects will undergo a hyperinsulinemic-euglycemic clamp protocol, a cardiopulmonary fitness assessment, and body fat quantification procedures, immediately before and after the intervention. The specific aims of the study will be to determine if aerobic exercise enhances cognition for older adults with IGT, to evaluate whether exercise-induced change in insulin sensitivity predicts cognitive performance, and to relate exercise effects on insulin sensitivity and cognition to changes in specified biomarkers. The results of this study may provide support for a relatively simple and inexpensive treatment strategy that targets many of the health factors that influence risk of cognitive decline.

Inclusion criteria

• diagnosed with IGT using OGTT, at least 55 years old, sedentary (elevated HR & SOB < 3x/wk for <30min each occasion), good overall health, willing to exercise at least 4 days/week for 6 mos

Exclusion criteria

• Significant neurologic disease that might affect cognition, such as AD, stroke, Parkinson's disease, multiple sclerosis, or severe head injury with loss of consciousness; significant medical illness or organ failure, such as liver disease, significant elevations in liver function tests, kidney disease, and uncontrolled hypertension (BP > 140/90 on medication); cardiovascular disease defined as any acute cardiovascular abnormality, such as new or unstable angina, uncontrolled irregular heart beat (treated a-fib and occasional PVC's are OK) or symptomatic heart failure, acute shortness of breath for any reason, or clinically significant edema; chronic lung disease, (COPD/emphysema); musculoskeletal impairment (impaired walking); current use of anti-psychotic, anti-convulsant, anti-coagulant, sedative medication, or cognition-enhancing medications; current or previous use of hypoglycemic agents or insulin.