Exercise boosts the brain — and mental health
They know that exercise has profound effects on the structure of the brain itself, as well as providing other, more subtle benefits, such as focus, a sense of accomplishment, and sometimes social stimulation — all of which are therapeutic in their own right. And while more is generally better, even simple amounts of physical activity, such as daily walking, can provide significant mental health benefits.
“Physical activity is a very powerful intervention,” said Anders Hofland, a clinical psychologist at the University of Bergen in Norway.
Joseph Firth, a mental health researcher at the University of Manchester in the UK, says this knowledge is barely starting to spread in practice. Just ask the hundreds of people who receive mental health care how many are getting prescriptions for exercise as part of that care. “You won’t find much,” Firth says.
Some of the strongest evidence for the mental benefits of exercise has focused on depression. In 2016, Hovland and colleagues searched the published literature and identified 23 clinical trials that tested the effectiveness of exercise in treating depression. The exercise was clearly effective Researchers have concluded in a few studies that it is comparable to antidepressants.
And exercise has many benefits. For starters, it usually takes several weeks for antidepressants to show their full effect. Exercise can improve mood almost immediately, says Brett Gordon, a sports psychologist at Penn State College of Medicine, making it a valuable addition to front-end treatments like medication or therapy. Plus, he says, exercise can counteract some of the unpleasant side effects of antidepressants, such as weight gain.
Additionally, exercise has few negative side effects commonly associated with medication. “Many people with mental health issues are not motivated to start treatment for the rest of their lives and are interested in other options. Exercise can be one of those options,” said Jacob Meyer, an exercise psychologist at Iowa State University.
But researchers are still figuring out how muscle exertion acts on the brain to improve mental health. For most biomedical questions like these, animal experiments are the first stop, but they are not helpful in studies of mental health problems.
“Mental health is so uniquely human that it can be difficult to make a good leap from animal models,” Mayer says.
Just scratch the surface
It doesn’t seem to have much to do with cardiovascular fitness or muscle strength – the two most obvious benefits of exercise. Smith says something else has to happen that is more important than just physical fitness.
One possibility is that exercise strengthens the brain and body. Exercise releases a protein known as brain-derived neurotrophic factor (BDNF). BDNF stimulates the growth of new brain cells, likely including the hippocampus, a brain region important for memory and learning. Since the hippocampus is usually smaller or distorted in people with depression, anxiety, and schizophrenia, boosting BDNF through exercise may be one way physical activity can help manage these conditions.
Certainly, studies show that people with depression have lower levels of BDNF — in particular, one of the effects of some antidepressants is to increase production of this molecule. Researchers haven’t directly shown that an exercise-related increase in BDNF reduces depressive symptoms, but it’s a promising possibility, Hovland says.
Exercise can also help treat anxiety disorders. The brain changes stimulated by BDNF seem to improve learning, which is an important part of some anti-anxiety treatments – so it’s possible that exercise improves the effectiveness of such treatments. For example, one treatment for PTSD involves exposing patients to a fearful stimulus in a safe environment, so patients learn to reset their responses to trauma-related cues—and the better they learn, the more durable this response can be.
Kevin Crombie, a neuroscientist at the University of Texas at Austin, and colleagues tested this idea on 35 women with PTSD. After learning to associate a specific geometric shape with a mild electric shock, the volunteers saw the same shape over and over without the shock knowing that the alarm was now safe. After a few minutes, half of the volunteers ran for 30 minutes or walked uphill on the treadmill, while the other half made only light movements.
Exercise also stimulates the release of cannabinoids, which are molecules important in modulating connections between brain cells. This may be another way to reinforce the learning underlying successful treatment of depression, PTSD, and other mental health disorders.
Physical activity also moderates the body’s stress response and reduces inflammation, thus fairly helping people with mental illness. “We just scratched the surface,” Hovland says.
Changing brain structure isn’t the only way physical activity can benefit mental health. A habit of exercising on its own can help, Smith says.
For people with mental health issues, doing anything — anything — can distract them and prevent them from ruminating. A review of the published literature found that placebo exercise — that is, gentle stretching, too light to have any physiological effect — had any effect. Almost half of the beneficial effects on mental health I also did heavy exercises.
Regular workouts also give athletes a visible sense of progress as their strength and fitness improve. Gordon says this sense of accomplishment can help ease some of the burden of anxiety and depression.
Even light activity — just moving around during the day rather than sitting for hours at a time — can help.
In a study of more than 4,000 adolescents in the United Kingdom, Aaron Kandola, a psychiatric epidemiologist at University College London, and colleagues found that young adults who engaged in more light activities during the day, Reduce the risk of depressive symptoms of those who spend most of their time in a sitting position.
Exercise has powerful benefits for people with mental illnesses that go beyond the effects of the diseases themselves. Firth says that many suffer from related problems such as social withdrawal and a decreased ability to have fun. Standard medications reduce some symptoms, but do nothing to treat these other problems. Exercising – especially as part of a group – can help improve their mood and enrich their lives.
Importantly, people with serious mental illnesses such as major depression and schizophrenia are also more likely to have serious physical health problems such as obesity, heart disease and other chronic diseases. As a result, their life expectancy is 10 to 25 years lower than that of unaffected people.
“Reducing these health risks is really critical right now,” Candola says. “This is the great cry of exercise: We already know that it can improve physical health. If it also has mental health benefits, it could be a very important adjunct to therapy.”
Bob Holmes is a science writer who lives and practices in Edmonton, Alberta. This article originally appeared famous magazineAn independent press company for annual reviews.
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