Share on PinterestMore evidence emerges suggesting that staying fit can help protect your brain health as you age. Image credit: Giselleflissak/Getty Images.
- Dementia affects more than 55 million people worldwide, with 10 million diagnosed every year.
- Studies suggest that keeping fit helps to reduce the risk of cognitive decline.
- A new study in older adults has shown that higher cardiorespiratory fitness is associated with better cognitive performance, even in people with a genetic predisposition for dementia.
Dementia is increasing in prevalence worldwide. It affects more than 55 million people, and is the seventh leading cause of death globally.
According to the Centers for Disease Control and Prevention (CDC), factors that increase dementia risk include:
- lack of physical activity
- uncontrolled diabetes
- high blood pressure
- hearing loss
- tobacco and alcohol use.
Some people also have a genetic predisposition, caused by the APOE e4 gene, for example.
However, studies increasingly suggest a positive association between physical activity and reduced risk of cognitive decline.
How is physical activity linked to brain health?
Physical activity helps people maintain their cardiorespiratory fitness — the ability of the cardiovascular and respiratory systems to provide muscles with oxygen during exercise.
Claire Sexton, DPhil, Alzheimer’s Association senior director of scientific programs and outreach, told Medical News Today that:
“The science on dementia risk reduction is evolving. Growing evidence shows that modifying certain risk factors and promoting healthy behaviors can reduce the risk of cognitive decline and possibly dementia. As many as 40% of dementia cases worldwide may be attributable to modifiable risk factors.”
A new study has reinforced these findings, suggesting that older people, even those with the APOE e4 gene, might be able to reduce their dementia risk by maintaining cardiorespiratory fitness.
The observational study found that higher cardiorespiratory fitness was associated with better cognitive performance across several functions that are susceptible to decline during aging.
The study is published in the British Journal of Sports Medicine.
“This study found a positive association between cardiorespiratory fitness and cognition. While these findings are in line with previous research, this study is valuable as it combined a gold-standard fitness test with multiple measures of cognitive function,” Sexton, who was not involved in the research, told MNT.
Study focuses on older people with lower fitness levels
The researchers recruited 648 participants aged between 65 and 80 years of age in three locations — Boston, Pittsburgh, and Kansas City, all in the United States.
All were cognitively healthy, and did not have diabetes, neurological, or severe cardiovascular conditions. Anyone who reported more than 20 minutes of structured moderate to vigorous physical activity at least 3 times a week was also excluded from the study.
At the start of the 12-month study, researchers assessed the participants’ cardiorespiratory fitness using a graded exercise test on a motorised treadmill.
Participants walked at 1.5-3.5 miles per hour (mph), to achieve 70% of age-predicted maximal heart rate. The treadmill speed was maintained throughout the test, with a 2% increase in grade every 2 minutes.
Researchers monitored oxygen consumption (VO2), blood pressure, electrocardiogram (ECG) measurements, and rating of perceived exertion (RPE) throughout the exercise test. They used the highest oxygen consumption recorded during the test — VO2max — as a measure of cardiorespiratory fitness.
Participants had an average VO2max of 21.68 milliliters per kilogram per minute (ml/kg/min). A good VO2max for men is around 30–40 ml/kg/min, and for women around 25–35 ml/kg/min.
They identified carriers of the APOE e4 gene from blood tests, and recorded whether participants were taking beta-blocker medication, to assess whether cardiorespiratory fitness had similar effects in these individuals.
Greater fitness linked with better cognitive function
All participants undertook 2 days of comprehensive neuropsychological evaluation to assess their processing speed, working memory, visuospatial processing, episodic memory, and attentional control.
The researchers found that those with greater cardiorespiratory fitness performed better in all five of the cognitive functions assessed. This association was seen in participants of all ages and even in those with the APOE e4 gene and on beta-blockers.
Ryan Glatt, CPT, NBC-HWC, brain health coach and director of the FitBrain Program at Pacific Neuroscience Institute in Santa Monica, CA, who was not involved in this study, welcomed the findings.
“The findings are consistent with prior research, reinforcing the importance of cardiovascular health for brain aging. While the study is not definitive, it adds weight to existing recommendations,” he told MNT.
However, he cautioned that: “The study provides valuable insights into the association between cardiovascular fitness and dementia risk, but as an observational study, it cannot confirm causation. Findings should be considered as part of a larger body of evidence.”
How cardiorespiratory fitness may improve brain health
Clifford Segil, DO, a neurologist at Providence Saint John’s Health Center in Santa Monica, CA, described how poor cardiovascular health not only leads to physical health issues, but may contribute to dementia:
“Poor cardiovascular health can result in cardioembolic strokes and cause multi-infarct or vascular dementia which is a subcortical dementia with cognitive slowing which is different to Alzheimer’s dementia which is a cortical dementia characterized by more recent than remote memory loss. Poor heart health does cause poor brain health and ischemic stroke which cause vascular dementia.”
But maximising cardiorespiratory fitness may help to reduce these risks. The authors of the current study suggest that mechanisms may include “effects of aerobic fitness on cerebral blood flow, oxidative stress, synaptogenesis [the creation of new links between brain cells], neurotrophic factors [which contribute to the development and management of the nervous system], neurotransmitter systems, and others”.
Glatt agreed, telling MNT that “improved cardiovascular health may reduce dementia risk by enhancing blood flow, lowering inflammation, and supporting overall brain metabolism.”
However, he cautioned that while these mechanisms are plausible, they require further verification.
Small changes can protect memory and thinking with age
Effective strategies to combat the rise in dementia cases are essential, Sexton told us:
“Two-thirds of Americans have at least one major potential risk factor for dementia. The need for effective risk reduction strategies to help all communities grows larger by the day. Without any change, the number of Americans with Alzheimer’s could nearly double by mid-century.”
She emphasized that getting regular exercise and staying physically fit is key to helping protect memory and thinking. Other important measures outlined by the Alzheimer’s Association include:
- challenging your mind by learning new skills
- controlling blood pressure and managing diabetes
- getting appropriate and regular sleep
- eating healthy foods and controlling your weight.
“For optimal benefit,” she told us, “incorporate as many of these as you can into daily living, but even incorporating just a few can put you in the right direction. It’s never too early or too late to start.”
