For the first time in human history, the elderly are more numerous than the young.
This presents a major challenge for the health sector. Dementia is probably the scariest thing – a debilitating condition that erases memory; an illness with no cure, at least for now. But we are not necessarily condemned to it. Because physical activity protects us from losing our memories, and according to our most recent studies, it’s never too late to get started. As an associate professor in the kinesiology department of MacMaster University, I lead a team of researchers from the NeuroFit lab where we have shown that physical inactivity contributes just as much as genetics to the risk of dementia.
Our research suggests that the intensity of the exercises is a significant element. We recruited sedentary seniors into a new physical activity program, and in just twelve weeks, their memory improved. But this only happened in those who walked at a higher intensity, and their memory boost was directly linked to the improvement in their physical condition. The next step will allow us to understand how physical activity changes brain activity – so that we can establish tailor-made routines to counter the effects of ageing on brain health. Read more: When is the best time to start physical activity? Now.
Training for a healthy brain As the population ages, we all run the risk of developing dementia. Because part of our destiny is predetermined by biological factors. Ageing is a primary risk factor for dementia, and certain genes also increase the likelihood. But we have recently started to recognize the role played by our lifestyle. New evidence points to a decrease in cases of neurodegenerative diseases, despite the ageing of the population.
And the reason is found in the improvement of our living conditions, education, and health care. One of the biggest game-changing risks is physical inactivity. And it is this observation that offers us the possibility of forming a healthier brain. Read more: The fight against Alzheimer’s disease must be rethought Physical activity lowers the risks A study carried out by my laboratory analyzed the interaction between genetics and physical activity on a group of over 1600 elderly people who participated in the Canadian Study of Health and Aging. About 25 per cent of our sample was at risk for genetic dementia, but the majority (about 75 per cent) were not.
This sample is representative of the population as a whole. None of the participants had symptoms of dementia at the start of the study, and we followed up five years later. Here’s what we found: 21 per cent of people at risk for their genetic makeup developed symptoms of dementia, and physical activity had no effect on them. On the other hand, in subjects without genetic risk, those who were physically active presented much lower risks of dementia than those who were inactive. Critically, inactive people presented a level of risk equivalent to that which was genetically predisposed to dementia.
In other words, physical inactivity can cause dementia even if the genes do not predispose it. You can’t change your genes, but you can change your lifestyle! Exercise acts like fertilizer It turns out that physical activity helps brain regeneration: it grows new neurons in the hippocampus, which improves memory.
While we don’t fully understand how it works, we do know that exercise increases the brain-derived neurotrophic factor (BDNF), which acts as a fertilizer that promotes the growth, functioning, and survival of new cells. These new neurons are arranged like pieces of a puzzle, each element of which represents a different aspect of memory. When we have more new neurons, we are able to create more detailed memories that are less likely to be wrong.
For example, we will remember if we took our medication yesterday or today, or where we parked our car in a congested parking lot. We have shown that physical activity improves neurogenesis of memory, both in young adults and in older people. Sweating matters! Seniors participated in three weekly sessions. Some did high-intensity interval training, others continued moderate-intensity training, while a control group did only stretching. The high-intensity interval training protocol included four sets of four minutes of treadmill exercise, followed by a cool-down period.
The moderate-intensity continuous training program included a period of aerobic exercise of medium intensity over a period of 50 minutes. Each exercise was adapted to take into account the physical condition of the participants. Only the seniors in the high-intensity interval training group exhibited symptoms of improvement in neurogenetic memory. No improvement was seen in people who followed a continuous training program of moderate intensity, nor in the control group. These results are promising because they suggest that it is never too late to benefit from improved brain health by being active.
But if you start late and want quick results, you will need to increase the intensity of your exercises. You can do this by incorporating hills into your daily walking routine and speeding up the pace between two poles. This will allow you to keep dementia at bay and contribute to healthy ageing for an increasingly large population.