Moderate- to high-intensity exercise does not modify cortical ß-amyloid in Alzheimer's disease.

ABSTRACT

INTRODUCTION: Animal models of Alzheimer's disease show that exercise may modify ß-amyloid (Aß) deposition. We examined the effect of a 16-week exercise intervention on cortical Aß in patients with mild-to-moderate Alzheimer's disease. METHODS: Thirty-six patients with Alzheimer's disease were randomized to either one hour of aerobic exercise three times weekly for 16 weeks or usual care. Pre and post intervention, 11Carbon-Pittsburgh compound B positron emission tomography was carried out to assess cortical Aß, and quantified using standardized uptake value rations (SUVRs). RESULTS: The intervention showed no effect on follow-up SUVRs in a covariance analysis with group allocation, baseline intervention SUVR, age, sex, and baseline Mini-Mental State Examination as predictors. Change in SUVRs did not correlate with changes in measures of physical or aerobic fitness. DISCUSSION: The present findings do not support an effect of exercise on Aß. However, the relatively short intervention period may account for a lack of efficacy. Further studies should test earlier and longer interventions.