5 Things You Should Know About Physical Activity and Brain Health
When it comes to your brain health, you have more control than you might think. Many physical, lifestyle, and social-emotional factors influence your brain, improving brain function and preventing age-related disease. But across all these factors, physical activity likely has the broadest impact.
So how does physical activity affect your brain? Two experts weigh in.
Christiane Wrann, DVM, PhD, a neuroscientist and leader of the Program in Neuroprotection in Exercise at the Mass General Brigham Heart and Vascular Institute and the McCance Center for Brain Health at Massachusetts General Hospital, studies brain health on a molecular and cellular level.
Mass General Brigham neurologist Jonathan Rosand, MD, MSc, co-founder of the McCance Center, lead developer of the Brain Care Score (BCS), and founder of the Global Brain Care Coalition, helps patients protect and improve their brain health.
1. Physical activity improves your sleep.
The number one result you’ll often notice from increasing your movement is improved sleep, according to Dr. Rosand. Physical activity helps you fall asleep faster, sleep better, and sleep longer. It can even improve sleep disorders such as insomnia and sleep apnea. And quality sleep has positive effects on your brain across the board.
“Once you get better sleep, everything is better,” says Dr. Rosand. “We know that sleep deprivation hinders your memory. We know that it makes it harder to pay attention and leads to a lower threshold for becoming frustrated.”
Sleep affects many pathways in your brain, including those involved in memory, mood, and executive function (skills such as attention, planning, self-control, and decision-making). Sleep is also the time when your brain cleans out toxins, including harmful proteins associated with Alzheimer’s disease.
2. Physical activity protects your memory as you age.
Research shows that walking about 3,800 steps per day decreases your risk for dementia by 25%. Walking about 9,800 steps per day decreases your risk by 51%. The benefits of physical activity on the brain as you age have been well-studied.
Groundbreaking research from Dr. Wrann and colleagues at Mass General Brigham discovered exactly how physical activity protects your brain, specifically from Alzheimer’s disease. Their findings uncovered that cells in the hippocampus (the brain’s memory center) respond to exercise with changes in their gene activity and expression. These cells have a range of responsibilities, from monitoring brain blood flow to removing brain toxins.
“Alzheimer's disease affects virtually all the cell types we've looked at, but exercise has restorative effects,” explains Dr. Wrann. Physical activity creates changes in gene activity that lead to:
- New neurons (nerve cells): New neurons grow and become part of existing brain networks.
- Preserved neurons: An increase of support cells in the brain helps protect against cell death.
- Reduced brain inflammation: Inflammation decreases in the brain, which protects against disease and cell damage.
- Synaptic plasticity: Your neurons grow and strengthen new connections with each other.
How long does it take for exercise to change your brain?
Some changes happen immediately, while others take more time to develop with consistent physical activity. For example, a new neuron in a mouse brain takes 30 days to grow. Dr. Wrann and colleagues at Mass General Brigham are working toward creating a tool that can measure your brain health based on cellular and molecular changes.
But for now, “measuring your heart rate is one way to see how you’re doing,” says Dr. Wrann. “When your resting heart rate trends down over time, you’ve improved your fitness and probably your brain health.”
3. Physical activity impacts your mental health.
Movement has an almost immediate effect on your mental well-being. Many people report feeling less stressed directly after exercising. This shift comes from activated “feel-good” messengers in the brain, such as endorphins, dopamine, and serotonin. Over time, levels of cortisol (a hormone linked to stress, inflammation, and disease) decrease.
Dr. Rosand also notices the effects of satisfaction from completing movement goals. “People who start doing more physical activity and measure it in some way that makes sense to them often gain a real positive feeling that lasts,” he says. “That positivity translates into taking more steps to take care of your health in other ways.”
Physical activity can also cause new neurons (nerve cells) to grow in the hippocampus. The hippocampus is commonly known for its role in memory and learning, but it’s also involved in emotion. “Growing new neurons can reduce anxiety and depressive-like symptoms in mice,” explains Dr. Wrann.
4. Every step counts.
Good news: Any type of physical activity is good for your brain (not to mention the rest of your body, too). You don’t need to run several miles every day. You don’t need to join a gym or learn a new sport.
“Our job in the clinic is to help people find ways to eliminate as many barriers as possible to getting active,” says Dr. Rosand. “What's most important is to help people move more and integrate that movement into their daily lives.”
Every step counts, and the more you can do, the better.
What kind of physical activity is best for your brain?
Most studies have looked at the benefits of aerobic exercise—movement that makes your heart pump faster, such as:
“Aerobic exercise has been shown in many clinical [human] and mouse studies to have the greatest benefits on brain health: improved learning and memory, structural function, blood flow to the brain, generation of new neurons,” says Dr. Wrann. The American Heart Association recommends 150 minutes of moderate physical activity (50% to 70% of your maximum heart rate) per week.
If you can get moving with a friend, it’s even better. Combining physical activity with social engagement can help keep you accountable. It can also help you avoid social isolation, which has been shown to negatively impact brain health.
A comprehensive approach to movement
Anaerobic exercise, such as weightlifting or interval training, is an important complement to aerobic exercise. Dr. Rosand also recommends stretching and yoga to each of his patients. In addition to making movement easier, these activities have a surprising effect on your nervous system.
“As we age, we tend to lose proprioception — the system that tells you where you are in space and is so fundamental to balance and to gait,” explains Dr. Rosand. “Stretching and yoga are a great way of stimulating that system. Signals from our feet need to be very rapidly transmitted to the brain so you can make second-by-second adjustments. Movement, stretching, yoga, and strengthening all contribute to keeping the overall system working well as we age.”
5. It’s never too late.
Studies have shown that older mice who have never run a day in their lives improve their cognitive abilities once they start exercising. Skills such as executive function, learning, and memory increase significantly.
Dr. Wrann and colleagues in the McCance Center have found similar results in sedentary middle-aged and older adults. Doing moderate-intensity physical activity for 12 weeks is enough to improve cognitive function, sleep quality, and the brain age index (BAI). BAI is a marker of your brain’s biological age compared to your actual age.
“Your brain has the ability to adapt and remodel, even if you haven’t exercised before,” encourages Dr. Wrann.
Reducing your risk for brain disease
Making healthy lifestyle changes, including increasing your weekly physical activity, can improve brain health regardless of genetic risk. You can reduce your risk for dementia, stroke, or late-life depression even if they run in your family.
Physical activity can also help restore executive function and memory in people with mild cognitive impairment (a condition that can develop into dementia). Many studies suggest that you can slow the progression of mild cognitive impairment to Alzheimer’s disease with exercise.
“When you’re ready, go ahead and start,” says Dr. Rosand. “You will see benefits no matter what the state of your brain is.”
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