Cardiovascular Fitness Associated with Reduced Risk of Dementia in Women

Written by Angeline A. De Leon, Staff Writer. A forty-four year population-based prospective study of 191 women demonstrated that cardiovascular fitness in midlife is associated with a reduced risk of dementia.

Decades of observational studies in aging research report evidence for the protective effects of physical activity against cognitive decline, and more specifically, risk of dementia, in older adults ¹. Studies show that aerobic exercise programs targeting cardiovascular fitness in healthy older adults are associated with moderate improvements in cognitive function ²; however, researchers have yet to definitively determine whether the link between physical activity and dementia is mediated by social and cognitive engagement associated with exercise or whether it varies according to levels of physical fitness. Because the majority of these studies rely on an observational study design and are based on self-reported measures of physical activity rather than objective metrics of fitness, there is insufficient evidence to establish whether the improvement in the cognitive function of older adults is indeed a direct result of improved cardiovascular fitness ³. Although currently no data from randomized control trials have been able to relate fitness to dementia incidence, at least one population-based prospective study shows evidence indicating an association between poor self-rated fitness during mid to late life and increased risk of dementia over a follow-up period of 25 years ⁴. Given that middle age has been considered a critical time period for the impact of cardiovascular risk factors on cognitive functioning ⁵, Swedish researchers at the University of Gothenburg sought to elucidate the relationship between midlife cardiovascular fitness and dementia incidence by tracking the objective fitness of a population of women and their cognitive status over a follow-up period of 44 years.

A population-based prospective study ⁶ was conducted in a sample of 1,462 women (aged 38-60 years) from which a subsample of 191 women were further tested. In this group, participants completed an evaluation of cardiovascular fitness using a stepwise-increased maximal ergometer cycling test which was performed until exhaustion. Neuropsychiatric examinations were performed at baseline and intermittently over a period of 44 years, and dementia was diagnosed based on psychiatric examinations as well as informant interviews and medical records.

In total, 23% of women were found to develop dementia with mean age at onset of dementia being 80.5 years. When categorized into three fitness groups based on peak workload, the cumulative incidence for all-cause dementia was 32%, 25%, and 5% for low, medium, and high fitness, respectively. Relative to medium fitness, the adjusted hazard ratio for dementia during the 44-year follow-up period was 0.12 (95% Confidence Interval: 0.03-0.54) for those with high fitness and 1.41 (95% CI 0.72-2.79) for those with low fitness. Mean time to dementia onset was delayed by 5 years for those with high fitness, compared to those with medium fitness.

As one of the longest prospective studies in aging research conducted, data from the study highlight the role of physical fitness in preserving cognitive function in older adults. Findings shows a significant relationship between high cardiovascular fitness during midlife and reduced risk for dementia. Therefore, efforts to prevent dementia should focus on improvement of cardiovascular fitness not just in early life, but during midlife as well. Future research is needed to establish direct causality and to determine when during the life course the cognitive benefits from high cardiovascular fitness is greatest. 

Source: Horder H, Johansson L, Guo X, et al. Midlife cardiovascular fitness and dementia: a 44-year longitudinal population study in women. Neurology. 2018; 0: e1-e8. DOI: 10.1212/WNL.0000000000005290.

Copyright © 2018 The Author(s). Creative Commons Attribution License 4.0 (CC BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Posted April 3, 2018.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

References:

1. Rolland Y, van Kan GA, Vellas B. Physical activity and Alzheimer’s disease: from prevention to therapeutic perspectives. Journal of the American Medical Directors Association. 2008;9(6):390-405.
2. DeFina LF, Willis BL, Radford NB, et al. The association between midlife cardiorespiratory fitness levels and later-life dementia: a cohort study. Annals of internal medicine. 2013;158(3):162-168.
3. Smith PJ, Blumenthal JA, Hoffman BM, et al. Aerobic exercise and neurocognitive performance: a meta-analytic review of randomized controlled trials. Psychosomatic medicine. 2010;72(3):239.
4. Kulmala J, Solomon A, Kåreholt I, et al. Association between mid‐to late life physical fitness and dementia: evidence from the CAIDE study. Journal of internal medicine. 2014;276(3):296-307.
5. Barnes DE, Yaffe K. The projected effect of risk factor reduction on Alzheimer’s disease prevalence. The Lancet Neurology. 2011;10(9):819-828.
6. Hörder H, Johansson L, Guo X, et al. Midlife cardiovascular fitness and dementia: A 44-year longitudinal population study in women. Neurology. 2018:10.1212/WNL. 0000000000005290.