- As dementia rates rise in the United States, scientists are trying to understand what factors increase the risk of developing these conditions.
- It already exists evidence that physical fitness could help reduce the risk of developing dementia.
- A recent study concludes that cardiorespiratory fitness is, indeed, linked to the risk of developing Alzheimer’s disease and related disorders (ADRD) later in life.
Leveraging the Wide Range of People Receiving Care in the Veterans Health Administration (VHA), first author Dr. Edward Zamrini and his colleagues studied 649,605 military veterans between the ages of 30 and 95.
These people had not been diagnosed with DARD and had taken a treadmill exercise test (ETT) as part of their routine care.
The scientists analyzed the records of these individuals for the diagnosis of SARD over an average of 8.8 years.
Dr. Zamrini, lead author Professor Qing Zeng-Teitlerand their colleagues compared the results of the ETT and the incidence at which SARD developed in these people.
Exercise tolerance testing helps quantify fitness levels using a measurement standard called MET, or task metabolic equivalence.
In this study, the authors divided the participants into five groups based on the METs they could achieve, from lowest to highest fitness: on average, about 3.8 to 11.7 METs.
For comparison, 1 MET is equivalent to sitting quietly, yoga obliges
Scientists have found that people who are less fit are most at risk of suffering from ADHD. Conversely, very fit people were the least likely to develop ADRD.
Dr. Zamrini, director of neurology at Irvine Clinical Research, assistant professor of clinical research and leadership at George Washington University and assistant professor of neurology at the University of Utah, told Medical News Today:
âOur study found a strong inverse graded association between cardiorespiratory fitness and reduced risk of [Alzheimerâs Disease]. This means that the fitter a person is, the more likely it is that if they developed AD, they would develop it later.
Specifically, the researchers found that, compared to the least fit participants, the fittest were 33% less likely to develop ADRD. Similarly, the second fittest group was 26% less likely to develop ADRD, the third fittest group was 20% less likely and the fourth fittest was 13% less likely.
âThere are two main factors that influence cardiorespiratory fitness: genetics and exercise. We can’t change our genetics,â he continued, âbut we can improve our cardiorespiratory fitness through a sensible exercise program. Our study also demonstrates that we don’t need to become marathon runners to reduce our risk. Even small increases in cardiorespiratory fitness can help! Â»
Dr Scott Kaisera board-certified geriatrician and director of geriatric cognitive health for the Pacific Brain Health Center at the Pacific Neuroscience Institute in Santa Monica, California, developed for DTM:
“You can’t prove that it was low fitness that caused the dementia. But, having said that, the association was so clear, not only in the strength of the association but in the nature of the association. The way it correlates so closely with increased fitness levels reduces the risk of dementia, it’s a very compelling association.
“There are many other studies that have sought to prospectively affirm this link between physical fitness and dementia risk and to confirm that regular and recommended exercise can reduce [a personâs] risk of developing dementia,â Dr. Kaiser continued.
âThus, studies like the [worldwide] FINGER study, out of Finland, where they actually prospectively study populations over time – there’s just growing evidence [â¦] that if you want to lower your risk of dementia and maintain a healthy brain, you need to exercise regularly and pursue other activities to improve your cardiorespiratory fitness.
What do these results mean? Dr. Zamrini clarifies:
âMy advice to anyone who is concerned about their risk of [Alzheimerâs disease] it’s ‘living as healthy a lifestyle as possible’. There are several lifestyle measures considered beneficial. These include exercise, diet, adequate sleep, and mental activity and social engagement. The strongest evidence relates to exercise.
DTM asked Dr. Kaiser whether ethnic or socioeconomic factors play a role in the development of dementia. Dr. Kaiser explained:
âWhen you talk about ethnic and socio-economic demographics, the reality we face right now is that research shows that older Latinos are about 1.5 times more likely than older whites to develop [Alzheimerâs disease].â
“And African Americans are twice as likely,” he continued, “so there are real equity issues at play here. It’s also a more common disease in women. So finding the root cause of these differences and being able to address them is really, I think, one of the biggest challenges that we collectively face going forward. It’s a big problem. I really believe that can be resolved.
DTM asked Dr. Zamrini if ââthere were any limitations in interpreting the study results. He observed:
âThis is an epidemiological study. Such studies do not prove cause and effect. However, the strength of epidemiological studies lies in the number of subjects studied. The large numbers in our study and the adjustments we made for comorbidities strengthen our findings.
âOur study was done by looking at (anonymized) data from veterans. Thus, the study may not be fully generalizable to the general population.
On gender differences in dementia, Dr. Zamrini explained that âdue to the large data set, although the proportion of women is small (5.7%), the number of women studied is 36,881 , which is still a large number, and we did not find a substantial difference in the results between men and women.
DTM asked Dr. Scott Kaiser about modifiable risk factors that are important in Alzheimer’s disease. Dr. Kaiser noted that the 2020 Lancet Commission Report on Dementia Prevention, Intervention and Care describes 12 modifiable risk factors linked to 40% of dementia cases worldwide.
“If they are at higher genetic risk, my patients need to focus on their cardiorespiratory fitness as part of their overall brain-healthy lifestyle, which means:
- keep fit
- have a healthy and balanced diet rich in fruits and vegetables
- get a good night’s sleep
- having meaningful relationships
- maintain a strong sense of social belonging
- avoid excess alcohol
- no smoking
- having opportunities to restore and reduce stress through meditation and other forms of self-care.
Full research results will be presented at the74th Annual Meeting of the American Academy of Neurology, which takes place in Seattle, April 2-7, 2022, and virtually April 24-26, 2022.