By: Will Oud, B.Sc.

Will Oud is a Research Assistant in Behavioural Neurology for the Brain Health Clinics, Rotman Research Institute, Baycrest (Toronto, ON).

Does Physical Activity
Improve Brain Health?

You know that last 5 km you just ran? That set of push-ups you just completed? That decision to walk to the store instead of jumping in the car? You’re not only exercising your body. As it turns, out you’re doing a load of good for your brain too. In other words, yes, you’re working out your brain. Nike’s “Just do it!” motto suddenly gained an all new epistemological significance.

We generally tend to think of exercise in terms of its benefits to our physical bodies. After all, following any physical activity we typically feel fatigue in our muscles, a shortness of breath and our heart beats faster. We naturally link these physical symptoms to the common knowledge we possess (and that you hear every other day) that regular exercise is among the most important things we can do to prevent disease and positively affect our overall health.

All that knowledge began several decades ago when a fitness revolution was spawned due to research that positively linked changes in lifestyle to the prevention of cardiovascular disease and related conditions such as diabetes, hypertension, obesity, etc.

Do you ever feel more alert or better able to focus after exercising? As an active individual, I certainly do, and experts alike in fields like mental health and neuroscience are becoming very interested in the role physical activity may have toward brain health. Their work could have considerable implications for how we confront the aging process, particularly the prevention and management of dementia. It may change how you look at exercise too.

Studies Linking Exercise & Brain Health

A growing body of research has been developed over the past few decades that is fairly comprehensive in exploring the connection between physical activity and brain health. The findings are being derived from cross-sectional (observation) studies as well as longitudinal (intervention) studies that have been showing a strong positive relationship between cardiovascular fitness and overall brain health in terms of structure and function. This correlation is seen in both older adults free of neurologic disease and clinical populations such as those with dementia, Parkinson’s disease, and depression.

Functional Benefits

The emerging evidence is encouraging, indicating that individuals in both normal aging populations and those with cognitive impairment/dementia perform better than comparable but less physically fit individuals on tests of general cognitive function (such as the mini-mental state exam). The cognitive benefit appears to be greatest for higher order processes (executive functions) like planning, multi-tasking, inhibiting irrelevant information, and working (short-term) memory. These are abilities that have been consistently shown to decline most with the aging process.

Structural Benefits

Results from imaging studies show significantly preserved gray matter volume for high fitness individuals over their less fit counterparts in cross-sectional studies. Longitudinal studies have produced promising findings too, showing that gray matter volume can actually be increased through cardiovascular training. Interestingly, exercise’s protective effect against neuronal death and capacity for growth appears to be greatest in the frontal, parietal and temporal cortices regions of the brain. These regions are thought to support the higher order process (executive functions) that were identified above.

These findings lend considerable support to the notion that physical activity may act as a protective mechanism against the brain aging process’ degrading effects.

How DOES Exercise Affect
Positive Change in the Brain?

Circulation throughout the body is improved during exercise when the heart begins to pump more blood. The increased blood flow is known to produce many positive effects on the body’s physical systems. The benefits seen in the brain may be widespread too and likely comparable in nature to those seen in the body. To discover what changes are occurring that may be affecting this positive trend, we must rely on work done with animals since we cannot efficiently study the brains of fellow humans in this way. The work in this field has shown that the neural mechanisms physical activity affects are widespread. They include:

• Growth Factors – Two major growth factors inside the brain of exercise trained animals are seen to increase significantly with exercise: BDNF (Brain Derived Neurotrophic factor), and IGF1 (Insulin-like growth factor). These are important signalling molecules that support growth and offer many protective effects in the brain’s neural environment.
• Blood Flow – Blood flow to the brain increases when exercise is started, similar to the increased flow to the rest of the body. Like the body’s tissues, the working neurons of the brain need glucose for fuel and optimal function. Increased blood flow to the brain – bringing with it more oxygen and nutrients – consequently improves those working neurons’ glucose metabolism potential. Regular exercise is also shown to lead to angiogenesis (an increase in the density and size of capillaries surrounding the neurons), thereby enhancing blood flow even while at rest.
• Neurogenesis – New neurons are generated in the brains of animals that run regularly. These new neurons develop mostly in the hippocampus (an important structure for memory and well-known to deteriorate with Alzheimer’s disease). The new neurons survive to contribute to the function of the cortex and become associated with learning and memory.
• Synaptic Plasticity – A process called Long Term Potentiation (LTP) – a cellular level mechanism for learning and memory – is a long lasting increase in the strength of communication between two neurons across the synapse (a tiny gap between two neurons where communication occurs via chemical signals called neurotransmitters). Stronger connections and thus communications between neurons is shown to improve brain function. In studies done with animals, running exercises have been shown to enhance the LTP process in the hippocampus.
• Neurotransmitters – Neurotransmitters are important chemicals in communication between neurons at synapses. For instance, deficits in neurotransmitters like Acetylcholine (ACh), serotonin, and dopamine have been implicated in the disease processes of Alzheimer’s disease, depression, and Parkinson’s disease. Levels of all three of these major neurotransmitters have been shown to increase within exercised animals’ Brains.

These mechanisms are likely to be interdependent upon one another, acting in combination to provide a more protective, healthy neural environment.

Beginning to Exercise in
Later Life – It’s Never Too Late

Taking up regular physical activity later in life may seem like an intimidating task. You may be reading this article while painfully imaging the participants in these studies exhausting themselves during intense workouts. The good news is, however, that the activities that can produce the benefits reviewed above do not need to be very strenuous. The exercise programs used in the studies mentioned were, for the most part, rather simple walking programs done multiple times a week for half an hour to an hour and designed to cause only a moderate increase in heart rate.

There are many simple things you can do if you wish to increase your physical activity. For older adults and those who haven’t exercised for a long time, you should start by slowly adding a bit more activity to your lifestyle. For instance, take up more chores around the house that get you moving like vacuuming, cutting the grass, or gardening. When you’re ready to partake in more regular activity, get started by asking your spouse, a family member, a friend, or a caregiver to go for a walk with you, take the dog out, or visit a friend’s house. Aim to do this 3 or 4 times a week for maximum benefit. Being active with someone whose company you value, or walking with a fond destination in mind will make it more enjoyable. Overtime, you may gradually increase the distance walked or the speed but be sure to stay within your comfort zone.

An Active Lifestyle for a Healthy Brain

Build activity into a regular part of your lifestyle, stick with it and, in doing so, you are building a solid foundation for lifelong brain health. This is all just another great reason to get active (as if we didn’t have enough already!).

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