Can exercise help repair the damaged brain?

It seems that exercise is not only beneficial for the heart, lungs and musculoskeletal system but it may also enhance brain function. Research in the laboratory of Dr. Dale Corbett, who holds a senior Canada Research Chair in Stroke and Neuroplasticity, is examining potential beneficial effects of exercise that help brain cells function more efficiently and also render them more resistant to damage that can occur with an injury such as stroke, or in the normal process of aging. Michelle Ploughman, a registered physiotherapist and doctoral candidate at Memorial, has experience with intensive rehabilitation on stroke patients at the Miller Centre in St. John's and she is now using animal stroke models in her research in Dr. Corbett's laboratory in the Faculty of Medicine.

Ms. Ploughman holds a Focus on Stroke Doctoral Fellowship supported by the Heart and Stroke Foundation of Canada, Canadian Institutes for Health Research, the Canadian Stroke Network and AstraZeneca. “Exercise could be a simple but potent method to help the brain recover from damage that occurs after stroke,” said Ms. Ploughman. “At the present time, aside from drugs that dissolve brain clots, there is very little medical treatment for stroke.

Patients depend on the rehabilitation process to regain their lost function.” The difficulty is that most patients in rehabilitation do not engage in endurance exercise. Ms. Ploughman said that colleagues Drs. Marilyn MacKay–Lyons and Lydia Makrides at Dalhousie University have shown that stroke patients spend only about four minutes per day in exercise that challenges the cardiovascular system. “In my practice as a neurological physiotherapist for the past 16 years, I have found that patients who perform endurance training such as treadmill walking or arm or leg bicycling before a therapy session relearn motor skills better than those who do not. It may be that exercise ‘primes' the brain for motor relearning to occur.”

This running wheel is used in testing the effects of exercise on brain function in rodents. The research is being carried out by Michelle Ploughman (L), under the supervision of Dr. Dale Corbett.

As a student in Dr. Corbett's laboratory, Ms. Ploughman is now able to investigate this potentially beneficial approach. “The first step is to determine what intensity, duration, and mode of exercise is optimal in terms of elevating growth factors and proteins that are important for learning and general neuronal health. Although it is difficult to draw direct parallels between humans and rodents, animals have surprisingly similar responses to both exercise and brain damage.”

Ms. Ploughman's work so far has been to analyze the disability in rats after stroke and design challenging exercise training levels, consisting of wheel-running, that are realistic and relevant to the clinical setting. “Thus far animal research has not been oriented towards actual rehabilitation practice, making it difficult to transfer the knowledge. So far this research puts in doubt the old adage that more is better. “Faster running speeds tend to increase stress hormones that can negatively influence neuronal health,” she explained. “We have found that animals who run at moderate speeds for short distances (300 metres) have just as much benefit as a long run for two kilometres. This suggests moderate exercise may be optimal for augmenting brain function.”

The next phase of this research is to design a challenging rehabilitation program incorporating the training exercise developed to see if the approach will actually influence recovery and brain rewiring after stroke. “The benefit of animal research is that we are able to perform detailed mechanistic analysis on the surviving brain tissue, for example measuring proteins, as well as have a group of animals that will have no rehabilitation at all, an impossibility in the patient setting,” she said. “My goal is to influence the way we provide rehabilitation services so that we maximize each patient's ability to return to as close to normal function as possible. The research we are doing leads the way in developing the concept of ‘brain exercise' and incorporating it in health care practice.”