Background: Despite the strong evidence of aerobic exercise as a disease-modifying treatment for Alzheimer's disease (AD) in animal models, its effects on cognition are inconsistent in human studies. A major contributor to these findings is inter-individual differences in the responses to aerobic exercise, which was well documented in the general population but not in those with AD. The purpose of this study was to examine inter-individual differences in aerobic fitness and cognitive responses to a 6-month aerobic exercise intervention in community-dwelling older adults with mild-to-moderate dementia due to AD. Methods: This study was a secondary analysis of the Effects of Aerobic Exercise for Treating Alzheimer's Disease (FIT-AD) trial data. Aerobic fitness was measured by the shuttle walk test (SWT), the 6-min walk test (6MWT), and the maximal oxygen consumption (VO2max) test, and cognition by the AD Assessment Scale-Cognition (ADAS-Cog). Inter-individual differences were calculated as the differences in the standard deviation of 6-month change (SDR) in the SWT, 6MWT, VO2max, and ADAS-Cog between the intervention and control groups. Results: Seventy-eight participants were included in this study (77.4 ± 6.3 years old, mean ± SD; 15.7 ± 2.8 years of education; 41% were female). VO2max was available for 26 participants (77.7 ± 7.1 years old; 14.8 ± 2.6 years of education; 35% were female). The SDR was 37.0, 121.1, 1.7, and 2.3 for SWT, 6MWT, VO2max, and ADAS-Cog, respectively. Conclusion: There are true inter-individual differences in aerobic fitness and cognitive responses to aerobic exercise in older adults with mild-to-moderate dementia due to AD. These inter-individual differences likely underline the inconsistent cognitive benefits in human studies.
Bibliographical noteFunding Information:
This research study was supported by the National Institute on Aging of the National Institutes of Health Award Number 1R01AG043392-01A1. The Clinical and Translational Science Institute and the Center for Magnetic Resonance Resources were supported by the National Institutes of Health National Center for Advancing Translational Sciences of the National Institutes of Health Award Number UL1TR000114 and the National Institute of Biomedical Imaging and Bioengineering Award Number P41 EB1058941, respectively. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
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- Alzheimer's disease
- Physical activity
PubMed: MeSH publication types
- Journal Article