By Stephen Beech via SWNS
High levels of physical fitness help lower the risk of dementia, according to a new study.
Researchers found that people with a genetic predisposition for the debilitating disease could reduce the danger by up to 35% through improved cardiorespiratory fitness.
High cardiorespiratory fitness (CRF) – the capacity of the circulatory and respiratory systems to supply oxygen to muscles – is linked with better cognitive performance and lower risk of dementia long term, suggest the findings published by the British Journal of Sports Medicine.
Scientists say that CRF declines increasingly with age as skeletal muscle is lost by around 3% to 6% per decade when people are in their 20s and 30s.
But the rate accelerates to more than 20% per decade by the time people reach their 70s.
Low CRF is a “strong predictor” of strokes and heart attacks and an early death from any cause, according to previous research.
Most previous studies investigating the impact of CRF on cognitive function and dementia risk included only small numbers of participants.
For the new research, Swedish scientists looked at a much larger sample by accessing data on 61,214 dementia-free people aged 39 to 70 years who enrolled in the UK Biobank study between 2009 and 2010 and were followed for up to 12 years.
A six-minute exercise test on a stationary bike was completed at the outset to estimate CRF, while cognitive function was estimated using neuropsychological tests.
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%) were diagnosed with 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.
Study author Professor Weili Xu, of the Karolinska Institute, said: “Compared with people with low CRF, the incidence rate ratio 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 or high polygenic risk score.”
She pointed out that it was an observational study, and as such, can’t establish cause and effect.
But Xu said: “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%.”
She added: “Enhancing CRF could be a strategy for the prevention of dementia, even among people with a high genetic predisposition for Alzheimer’s disease.”
Xu said further research on the relationship between CRF and brain health – especially in older people, and on the mechanisms by which CRF modifies the relationship between genetic risk and dementia – is needed.
