There is increasing evidence that regular physical activity may help preserve our cognitive function in old age. Studies are showing that not only can exercise reduce the risk of neurodegenerative diseases, such as dementia and Parkinson’s, but it might also slow the progress of these diseases after diagnosis. But how does it work? Medical News Today asked experts why and how exercise might help keep the brain young.

How might exercise help protect against dementia, Parkinson’s disease, and similar conditions? Image credit: Take A Pix Media/Stocksy.

On average, we are living longer, but we may not be living healthier. According to European Union figures, women can expect, on average, 64.5 healthy life years (HLYs), and men, 63.5.

But life expectancy in the EU is just over 83 years for women and 77.5 for men. So, on average, a person can expect to spend around 15-20 years with some sort of health problem.

And most of those years of ill health are likely to be the later years of life, and many people will develop a neurodegenerative disease.

Estimates indicate that 14–18% of people over the age of 70 years in the United States have some form of cognitive impairment. And some 10% of people in the same age group in the U.S. have dementia, a number that rises to 33% of those over 90.

But there are ways to help extend your HLYs, and evidence is increasingly suggesting that regular physical activity may be one of the most effective ways to help your body and brain stay healthy for longer.

Exercise makes us feel better — higher levels are associated with lower levels of depression, and it is thought this is due to a natural “high” from the release of endorphins and endocannabinoids, which can last for some time after exercising — but the physical effects last longer.

According to the Centers for Disease Control and Prevention (CDC), regular physical activity is “one of the most important things you can do for your health.”

Medical experts everywhere agree with that statement. Speaking to Medical News Today, Dr. Emer MacSweeney, CEO and consultant neuroradiologist at Re:Cognition Health, emphasized:

“Being physically active is one of the best things you can do for your body. Exercise helps protect against many diseases and keeps the heart, muscles, bones, and brain in optimum condition. Exercise promotes [the] oxygenation of the brain and stimulation of multiple neurochemicals.”

Exercise can reduce the risk of, among other conditions, cardiovascular disease, several types of cancer, and type 2 diabetes.

And, together with a healthy diet, it is a key part of maintaining a healthy body weight — another way to lower the risk of disease.

Research has shown that endorphins can relieve pain, and may reduce both inflammation and stress responses. Additionally, exercise can increase the beneficial effects of medications and other therapies for mental health conditions, such as depression.

“Exercise is particularly beneficial for mental health due to the chemical changes which occur in the brain and body, including the release of ‘feel-good’ chemicals, endorphins and serotonin,” Dr. MacSweeney explained.

Alzheimer’s disease is the most common form of dementia, affecting more than 5 million adults in the U.S. alone, and more than 55 million worldwide. Around 1 million people in the U.S. have Parkinson’s disease, with a further 90,000 cases diagnosed each year.

As populations age, the numbers of people with both diseases are predicted to rise. The World Health Organization (WHO) states that by 2050 there will be almost 140 million people with Alzheimer’s worldwide.

And the number of people with Parkinson’s could rise to 17 million by 2040.

Both Alzheimer’s disease and Parkinson’s disease are progressive diseases that are, ultimately, fatal. Symptoms of Alzheimer’s disease include memory loss, confusion, cognitive changes, and personality or behavior changes.

Parkinson’s is characterized by tremors, impaired coordination, depression, and other changes in cognitive function.

Currently, both Alzheimer’s disease and Parkinson’s disease are currently incurable, but treatments can help to alleviate symptoms and slow their progress, improving the quality of life of people with the diseases.

Increasingly, research is showing that exercise may also be useful in both delaying onset and slowing the progression of these, and other neurodegenerative diseases. In addition, exercise may be effective as an add-on therapy alongside current medications.

Dr. Jamie Adams, associate professor in the Department Neurology and the Center for Health and Technology at the University of Rochester Medical Center, NY, told MNT:

“Unfortunately, we do not have any disease-modifying therapies or treatments to prevent or slow the progression of Alzheimer’s disease or Parkinson’s disease. However, there is growing evidence that shows that regular exercise can help slow [the] progression of [the] disease. Regular exercise also has therapeutic and other health benefits.”

“My patients that exercise, feel better and do better,” she added.

“There are numerous studies assessing the link between exercise and reducing the risk of Alzheimer’s and other causes of dementia and it is imperative that this research continues. With every study, we learn more about the disease, which can lead to the development of new treatments,” said Dr. MacSweeney.

But why might exercise help prevent or slow these neurodegenerative diseases? There are several theories.

Inflammation, caused by the overactivity of immune cells — called microglia — in the brain, is a key feature of both Alzheimer’s disease and Parkinson’s disease.

This inflammation leads to the loss of nerve cells in the brain, with chronic overactivity of microglia leading to a cumulative loss of neurons.

Exercise can reduce the activity of the microglia cells, which are the immune cells of the nervous system. A 2021 study in older people with Alzheimer’s showed that regular exercise protected cognitive functioning by limiting microglial activity.

Another possible mechanism may be that exercise changes how the brain metabolizes iron. Iron accumulation is associated with the development of beta-amyloid plaques, a characteristic of Alzheimer’s disease.

A study from Finland found that, in mice, regular exercise reduced iron storage in the brain by decreasing levels of a protein called interleukin-6, which is also linked to inflammation. The mice with lower iron levels also had fewer beta-amyloid plaques.

In Parkinson’s disease, exercise demonstrably reduces the alpha-synuclein clumps that are associated with neurodegeneration.

A study found that irisin, a molecule secreted into the blood during endurance exercise, reduced these clumps, but had no effect on alpha-synuclein monomers that are important for transmitting nerve impulses.

Physical activity has also been shown to increase levels of two other important chemicals, as Dr. MacSweeney explained :

“Exercise stimulates the production of chemicals such as BDNF (brain-derived neurotrophic factor) and IGF (insulin growth factor) These help to stimulate new cell growth in certain areas of the brain and strengthen connections.”

Studies have shown that BDNF, administered externally, or produced via increased physical activity, may be useful as part of a therapeutic regime for Parkinson’s disease.

And the therapeutic use of IGF has been proposed for many disorders of the nervous system, including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis (ALS, or motor neuron disease), and multiple sclerosis (MS).

“Exercise is thought to encourage brain cell growth and survival, which may help reduce the risk of developing dementia. Studies have also shown that exercise increases the size of the brain structure linked to memory and learning.”

– Dr. Emer MacSweeney

“More research is underway looking at exercise intensity and symptoms of Parkinson’s disease, but data suggests that moderate to vigorous aerobic exercise where people are getting their heart rate up may slow [the] progression of [the] disease,” said Dr. Adams.

The type of exercise with the most benefit is open to question. One study suggests that a mere 6 minutes of high-intensity exercise may help delay the onset of both Alzheimer’s disease and Parkinson’s disease by increasing levels of BDNF.

Another study confirmed findings from several other studies by showing that both cycling and stretching reduced cognitive decline in older adults. While both types of exercise were better than no exercise, neither had a significant advantage over the other.

If high-intensity exercise is not an option, low-impact exercises can be beneficial too. Pilates has been shown to have a positive impact on balance, fitnessm and physical function in people with Parkinson’s disease.

Yoga not only benefits mental and physical health, but studies show that it may also have physiological and psychological benefits for people with Alzheimer’s disease, MS, and other neurological disorders.

“Motor skills that incorporate agility, balance, power, coordination, reaction time and speed have been shown to increase our executive function which is our ability to plan, focus attention, remember and reason.”

– Dr. Emer MacSweeney

Most important is ensuring that exercise, in any form, becomes part of a person’s regular routine. According to a 2022 study, regular exercise can change the progression of Parkinson’s disease. People who took up to 4 hours of exercise a week showed slower declines in balance and stability than those who did not.

And regular physical activity is certainly beneficial as part of Alzheimer’s disease prevention and treatment. One comprehensive review demonstrated that regular exercise could both reduce the likelihood of dementia and slow its progression.

But a key finding of the review was that a lack of physical activity increased Alzheimer’s disease risk.

Dr. MacSweeney advised:

“Exercis[ing] vigorously three times a week for 20 minutes or moderately five times a week for 40 minutes is good practice. However, the most important thing is to be consistently active! If you choose an exercise you enjoy doing you are more likely to stick to it.”

So there is increasing evidence that regular exercise might help to prevent neurodegenerative disorders and slow their progress.

As exercise also improves overall health and reduces the risk of many diseases, perhaps we should all follow the advice of Dr. Adams.

“Exercise can help build strength, reduce stress, improve sleep and fatigue, and may improve socialization,” she pointed out. “All of these benefits can help reduce cognitive decline. […] In the end, all exercise is beneficial and the best types of exercise are ones that people can commit to, sustain, and enjoy!“