Brain gains – The impact of exercise on the brain

An article I originally posted at Australia’s Science Channel

 

Exercise has a wide range of benefits for the body. It improves cardiovascular fitness, lowers blood pressure and reduces the chance of developing heart disease and stroke.

But more than just improving your fitness, aerobic exercise has a range of benefits for your brain too.

A recent study from researchers at UNSW Sydney showed that short burst of exercise after study could help you retain information better.

And there is other evidence that shows exercise can improve your memory, may help ward off dementia, and enhance your mental health. But how does working out boost your brain? And how much do you need to do?

 

Physical activity enhances neuroplasticity

Brain plasticity, or neuroplasticity, is the ability of brain cells (neurons) to modify the connections that they use to communicate with each other, which allows the brain to reorganise itself.

This process is vital for brain development, skill learning, memory formation, or recovery from brain injury.

One of the drivers of neuroplasticity are chemicals in the brain called growth factors.

These stimulate new cell growth, increase the formation of synapses – the communication points between neurons, and increase the survival of neurons.

In experiments, rats and mice which voluntarily ran on a wheel had increased amounts of growth factors in their brains, promoting this process.

Animals that exercise have an increase in brain-derived neurotrophic factor (BDNF), a growth factor that increases neuronal survival, enhances learning and protects against mental decline. In particular, exercise increases BDNF in the hippocampus, a key brain region for memory formation.

Other growth factors increased by exercise include Vascular Endothelial Growth Factor (VEGF), which promotes the growth of new blood vessels in the brain.

This increases blood flow and oxygen delivery to the brain. Exercise also increases Insulin-like-Growth Factor (IGF1), a key factor in the control of brain cell numbers.

 

Exercise boosts neurogenesis

The generation of new neurons is known as neurogenesis.

This process occurs in specific regions of the brain throughout life, in particular, the hippocampus. Newly created neurons are vital for learning as they are thought to increase the capacity of memory.

Experiments show increased neurogenesis in the hippocampus in lab rats and mice who have running wheels to exercise in, and some of these studies also point towards enhanced cognitive function in these animals. So not only does it promote more neuron growth, but those new neurons do actually make their brains more capable of learning.

In people, brain imaging studies have also found that the hippocampus is bigger in people who exercise regularly. This is important as a bigger volume can indicate more neurons and improved memory function.

Normally, neurogenesis slows down with age, and very low levels are linked to Alzheimer’s disease and dementia. It is thought that maintaining an active lifestyle could stave off these effects, maintaining both body and brain health as we age.

 

Exercise relieves stress, which has multiple benefits to the brain

Your body’s immediate stress response is a burst of energy to escape a dangerous situation – the fight or flight response. But stress over long periods is damaging. Chronic stress is experienced by many people and manifests with physical, mental and emotional symptoms.

In 2014, a quarter of Australian adults reported moderate to severe stress. Even more concerning, younger adults between 18-35 years old report much higher levels of stress and distress compared with older Australians. Stress is one of the key factors for the onset of mental health disorders including anxiety and depression.

Chronic stress has been shown to reduce neurogenesis, inextricably linking neurogenesis to mental health disorders. This also provides therapeutic mechanisms by which lifestyle changes, such as increasing exercise, may be a valuable part of treatment by boosting neurogenesis.

Stress also causes the release of the hormone cortisol, which in excessive levels is toxic, damaging and destroying neurons in the hippocampus. This has a particular effect in impairing your memory.

 

Gym regulars know that a sweaty workout helps them unwind and releases stress and tension that can build up across our busy lives.

Aerobic exertion can evoke that feeling of a “runner’s high” which scientists have pinned to the release of natural feel-good chemicals – endocannabinoids and endorphins – in the brain. These chemicals can relieve pain and promote a feeling of blissed-out wellbeing.

But as we also know that exercise can enhance neurogenesis, there is a dual benefit to regular workouts – combatting the toxic effects of cortisol on neurons, and promoting the growth of new ones.

 

How much exercise is required to boost your brain power?

You don’t need to do much to get these benefits – about half an hour of moderate-intensity physical activity most days of the week will do. Heading out for a brisk walk is ideal, and it can be part of your usual daily routine like walking to work or switching out from eating lunch at your desk to eating outside with a short stroll.

Any exercise that increases your heart rate and breaks you into a light sweat also benefits your brain.

Moderate-intensity exercises like swimming, cycling, stair climbing or dancing, even certain household chores that get your heart rate up can count!

So what does a neuroscientist do? I love high-intensity interval exercise or team training. I find the social aspect of group exercise is a great motivator for me to work out extra hard and the short intervals rapidly spike my heart rate. Plus, in no time you’re finished and feeling that post work out buzz.

 

Why is research into how exercise improves our brain power so important?

Research into how exercise can improve brain function is providing a way to help prevent dementia and cognitive decline. Dementia is rapidly increasing and is already a huge health burden worldwide. By the year 2050, it is estimated that more than 115 million people globally will have dementia, so changing sedentary lifestyle habits is important for maintaining a healthily aging population.

Scientists hope to pinpoint vital brain changes that occur at a cellular or molecular level when we exercise and harness them to improve brain health. Discovering these mechanisms could lead to better therapies for dementia and mental health disorders, dramatically improving the quality of life for those affected.

But there is a lot you can do at home and in your everyday life to reduce your risk, so head out for a walk, or dance around the house doing your chores – your brain will thank you for it.