People who are genetically predisposed to dementia may lower their risk by as much as 35% by improving their cardiorespiratory fitness.
A study published in the British Journal of Sports Medicine found that high cardiorespiratory fitness (CRF) is linked to better cognitive performance and a lower long-term risk of dementia, even among individuals with a genetic predisposition to the disease.
Cardiorespiratory fitness refers to the ability of the circulatory and respiratory systems to deliver oxygen to the muscles during physical activity. This capacity naturally declines with age, largely due to the loss of skeletal muscle. CRF typically decreases by about 3% to 6% per decade during a person’s 20s and 30s, but the decline accelerates to over 20% per decade by the 70s. Low CRF is a strong predictor of cardiovascular events such as heart attacks and strokes, as well as overall mortality.
Large-Scale Study Shows Protective Effects of CRF
Most previous studies investigating the impact of CRF on cognitive function and dementia risk included a small number of participants. For this study, the authors looked at a much larger group by accessing data on 61,214 dementia-free people aged 39-70 years who enrolled in the UK Biobank study between 2009 and 2010 and were followed for up to 12 years.
At enrolment, a 6-minute submaximal exercise test on a stationary bike was completed to estimate CRF, cognitive function was estimated using neuropsychological tests, and genetic predisposition for dementia was estimated using the polygenic risk score for Alzheimer’s disease. During the follow-up period of up to 12 years, 553 people (0.9%) received a diagnosis of dementia.
Participants were divided into three equal-sized groups standardized by age and sex according to their CRF scores for the analysis which showed that people with high CRF had higher cognitive function and a lower risk of dementia.
Compared with people with low CRF, the incidence rate ratio (IRR) of all dementia was 0.6 for people with high CRF, and the onset of dementia was delayed by 1.48 years. A high CRF also reduced all dementia risk by 35% among people with a moderate/high polygenic risk score.
Limitations and Considerations
This is an observational study, and as such, it can’t establish cause and effect, and the researchers acknowledge various imitations to their findings.
Most importantly, the number of dementia cases may have been underestimated because UK Biobank participants are generally healthier than the general population, plus individuals with certain health conditions were excluded from the exercise test making the population investigated ‘healthier’ still. The reliance on registries to identify dementia cases might have led to a further underestimation. Also, the submaximal exercise test used is considered less accurate than maximal exercise testing which requires participants to exercise to exhaustion, and any association between CRF change and dementia risk could not be examined due to the lack of repeat CRF measurements.
The authors conclude, “Our study shows that higher CRF is associated with better cognitive function and decreased dementia risk. Moreover, high CRF may buffer the impact of genetic risk of all dementia by 35%.”
They add that their findings suggest that, “Enhancing CRF could be a strategy for the prevention of dementia, even among people with a high genetic predisposition for Alzheimer’s disease.”
Further research on the relationship between CRF and brain health, especially in older adults, and on the mechanisms by which CRF modifies the relationship between genetic risk and dementia is needed, they say.
Reference: “Association of cardiorespiratory fitness with dementia risk across different levels of genetic predisposition: a large community-based longitudinal study” by Shuqi Wang, Liyao Xu, Wenzhe Yang, Jiao Wang, Abigail Dove, Xiuying Qi and Weili Xu, 1 February 2025, British Journal of Sports Medicine.
DOI: 10.1136/bjsports-2023-108048
The study was funded by the Swedish Research Council and the Karolinska Institutet Research Foundation.
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