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.
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.
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!).
Will Oud is a Research Assistant in Behavioural Neurology for the Brain Health Clinics, Rotman Research Institute, Baycrest (Toronto, ON).
Brain Health & Dementia Risk
A decade into the new millennium and it is well understood that Canada’s demographic landscape is changing – our most elderly population cohort is growing immensely. Advances in science, healthcare technology and medicine, along with better lifestyle choices, have resulted in individuals living longer lives and maintaining better physical health throughout their later years. Along with this will come the inevitable implications of an older population.
An impressive study recently commissioned by the Alzheimer’s Society of Canada – appropriately titled, “Rising Tide” – examines the impending tsunami-like impact of dementia on Canadian society. The study’s results are truly alarming. It estimates that about 500,000 Canadians are living with dementia today, already crowning it as the most significant cause of disability in those aged 65 and over. This number is expected to more than double in the next 30 years, increasing the number of those inflicted to 1,125,200 people by 2038. Such a dramatic increase represents not only a serious health concern but also a crippling economic burden for Canadian society. It is clear that we must begin addressing the issue now.
What Brain Health Means to You and I
Many of us will come to accept that living into our 70’s, 80’s, 90’s or beyond will eventually mean sacrificing some of our physical independence due to unpreventable physical frailty. We may need to employ services like homecare for the added assistance required in maintaining a certain level of personal independence. While for most this is an acceptable compromise in exchange for an extended lifespan, amongst our biggest unresolved fears and one most difficult to comprehend is the potential loss of our mental faculties.
Losing the ability to think for ourselves, to decide on the direction of our own lives as a result of the senility caused by a degraded brain, is not a comfortable concept even for the most stout of heart. For anyone who has witnessed the devastating effects of dementia on another – whether in a family member, friend, or as in my case with clients – the experience can become a very potent alarm, signalling the importance of educating ourselves of this health risk.
I welcome you to my Brain Health Series on the Premier Homecare Services Blog. I hope that with this first entry you will become convinced we should all begin paying more attention to this topic of brain health.
Shattering Traditional Modes
of Thinking about the Brain
In the not so distant past, the accepted concept of the adult nervous system was that it was a fixed static entity both in terms of function and structure. Remember hearing the expression, “You can’t teach an old dog new tricks”? Contrary to this ingrained maxim, many years of groundbreaking research – the work of many brilliant minds – has begun to offer a different way of thinking about the brain. We now view the brain as a very dynamic organ constantly changing both in function and in structure.
Evidence of Functional Change (Synaptic Plasticity)
Back in the middle of the 20th century, neuropsychologist Donald Hebb posited a theory, which has been summarized as, “[brain] cells that fire together, wire together”. This means that if a neuron (the cells which make up our nervous system and act by stimulating each other in a pathway) continually causes a neighboring neuron to fire, a metabolic change will take place that can, over time, strengthen the connection between the two. Neuroscientists like Michael Merzenich have applied this theory and observed significant functional rewiring of the cortex of primate and human brains, experimentally demonstrating that this theorized functional change occurs.
Evidence of Structural Change (Neurogenesis)
We used to think that the growth of new neurons was not possible after our childhood years. If someone were to experience brain injury there wasn’t much that could be done with them other than to help them cope with what functions remained because we believed that brain cells could not regenerate and the damage was permanent. We now know that through a process called neurogenesis, the development of new neurons is very much a possibility. Psychologist Elizabeth Gould has conducted pioneering research in this area of neuroscience. She has shown that the generation of neurons in the adult brains of monkeys does indeed occur. These newly created neurons arise from neural stem cells and migrate not only to the hippocampus – a part of the brain important for memory – but to the associative areas of the cortex that are important for higher cognitive function.
Until recently and most likely because of the traditional model of the static brain, the most focus on brain health has been given to the stages of older age and what happens in advanced brain failure like Alzheimer’s disease. Armed with this fresh knowledge regarding a more dynamic brain, we may begin to adopt a more holistic approach to brain health and focus on the greater process of brain aging. By turning our attention to what we can do in the areas of prevention, early intervention, and rehabilitation, we may be able to strengthen Canada’s brain health and reduce the burden of dementia on future generations.
Strengthening Brain Health – Strategies
for Slowing the Progression of Disease
Many scientists are actively searching for effective methods of promoting positive changes in our brains. The hope is to find solutions for preventing or slowing the loss of brain tissue during aging and disease progression, or for minimizing the impact of such losses. Much of the research that has shown noteworthy promise is in healthy lifestyle choices like physical activity, nutrition, the exercise of mental activity, and choice of environment. According to the Alzheimer’s Society, promoting brain health through lifestyle choices may be the most effective way of reducing the risk of Alzheimer’s disease and for slowing down its progression.
Through this blog series – Brain Health by Will Oud – I will take a critical look at contemporary research involving lifestyle choices and their potential effects on healthy brain aging and the prevention of disease. I’ll begin to sift through what advice is supported by valid research and what claims the literature just doesn’t back up. Follow-up four weeks from now for the next addition to the series.
For an interesting look at the research that’s being conducted in neural plasticity and some remarkable stories of the individuals who have benefited, I suggest Norman Doidge’s book “The Brain that Changes Itself”. It is also a “Nature of Things” CBC documentary: http://www.cbc.ca/video/#/Shows/The_Nature_of_Things/ID=1233752028