Grant: Project Grant

The arteries that enter the brain are approximately one centimeter wide. These arteries branch into smaller vessels, called arterioles. The branching is repeated until the vessels are many times smaller in width. It is at this small level that vessels supply brain tissue with the oxygen and nutrients required for regular function. A brain disease that targets these small vessels is called "small vessel disease" (SVD). In SVD the blood flow through vessels in the brain is impaired or restricted. We see signs of SVD on pictures collected during medical imaging, namely Magnetic Resonance Imaging (MRI). Older people, above 55 years old are more likely to have SVD than younger people. This is important because in Canada there are more people living in their senior years than people younger than 15 years old. Older people are also more likely to have a stroke: a blockage of blood flow in the brain. An estimated 1 in 5 strokes is caused by SVD. As we learn more about SVD in the human brain we will be in a better position to prevent old age impairments. This project seeks to discover new ways to visualize and understand SVD. Our approach is to develop "dynamic" and "functional" images using an MRI scanner. We will study how the brain's arterioles pulsate with each heartbeat and how the vessels react to a stimulus that causes them to expand, known as vasodilation. It is important to observe change over time and over the course of therapy. Therefore, we propose to gather these images and other assessments at the beginning of the study and after 12-weeks of aerobic exercise training. There is strong evidence that exercise is good for all the blood vessels in the body, including the brain, as it causes the blood vessels to dilate and increase the amount of blood flowing. This research can help us identify ways to treat and observe SVD.