Mental Health: Turning Back The Clock

neuroscience.jpg“One and two and three…,” shouts the instructor, shoving her arms up and down and from one side to other, while pushing up her opposite knee to her chest in a move worthy of a contortionist. “Come on, you can do it! Don’t forget to breathe,” she adds, exhaling.

The group (ranging in age from 65 to 80) desperately trying to follow her every move are hoping that exercise will make them feel healthier and keep trim, but little do they know that physical activity also has an impact on their brains. “We found that as little as 30 minutes of cardio three times a week can have an impact on the brain after just three months,” explains Louis Bherer, a neuroscientist at l’Université du Québec à Montréal and an expert in gerontology. “The key here is not intensity, but frequency.”

Strong scientific evidence is now emerging to prove that cardiovascular exercise can have far more of an impact on the brain than previously recognized. “The question is: can we delay the effects of aging and even protect people from them through exercise?” says Bherer. “Our answer is: yes, we can.”

Although not all cognitive functions weaken, some higher or executive functions of the brain tend to deteriorate with age. The executive functions are mainly controlled by the frontal lobes and are responsible for planning, organizing and allowing us to respond quickly to unpredictable situations — being alert, if you will. “Executive functions decline in humans as early as age 50 to 60, but we also see that their decline can be delayed with regular exercise,” says Bherer, who has been following in the footsteps of his former professor Arthur F. Kramer of the University of Illinois.

Kramer is also confident of the positive effects of physical activity on the brain. To prove it, gyms have been moved into his lab, and older people put to the test. In a typical study, a control group remains physically inactive, while another undergoes a simple aerobic training program. Both groups have their cognitive functions thoroughly tested prior to any training, then again at the completion of the study.

Over the past decade, Kramer and his team, which has now spread into research facilities around the world, have produced a mountain of evidence to show that even moderate exercise, on a regular basis, can enhance an older person’s performance on cognitive tests. Through functional imaging of the brain, Kramer’s team has seen parts of the brain in older people that appeared underused before the training program suddenly “light up” or become active once more. “Brain regions in the prefrontal, temporal and parietal cortex, which support the tasks and skills that we examined, changed their pattern of activation to … become more like activation patterns observed when younger adults perform the tasks,” he explains.

Research on rodents gave the first clues to this positive discovery. After running around a wheel to build cardiovascular strength, rodents were able to find their way out of a maze much faster. Postmortem examination of their brains showed new neurons and vascular structure, as well as increases in neuroprotective molecules and the connections between neurons. “This animal research was extremely inspiring and led us to think that exercise could postpone aging in humans as well,” says Kramer.

These findings hinted that the brain didn’t simply deteriorate in a linear fashion over time but that it had enormous plasticity. According to leading experts in the field of molecular biology, physical exercise makes such a big difference in performance that it can even change the brain’s structure.

A strong correlation has been found between exercise and the production of a protein called brain-derived neurotrophic factor (BDNF), which acts as a factory of cells in the hippocampus and increases the health and functionality of existing cells — particularly in the frontal lobes. “This suggests that cardiovascular fitness may restore neural health,” says Stan Colcombe, a Kramer group collaborator who has recently started another research group in Wales, to further investigate the impact of physical activity at the molecular level by measuring BDNF levels in blood samples.

“We now know that the brain can grow new cells, that the brain can reorganize itself after damage and that, as we get older, brain functions can be partially restored with proper exercise, sleep and eating habits, as well as learning new techniques,” says Donald Stuss, a neuroscientist and vice-president of research at Baycrest, a health science centre focused on aging in Toronto. Scientists have tested different types of exercise, such as flexing and stretching, to see if they produced the same results, but it appears that those which involved aerobic activity were most effective in helping the brain grow and stay healthy.

— Véronique Morin