Someone in Canada develops dementia every five minutes, a rate that is projected to more than double over the next thirty years.
Sunnybrook’s internationally renowned stroke expert, Dr. Sandra Black, is investigating a promising new area of brain research — the relationship between vascular disease, cognitive function and Alzheimer’s disease.
“Canadians often punch above their weight when it comes to neuroscience research, especially for dementia and stroke. The brain imaging facilities at CeRIGT have provided us with important physics and analytical expertise, allowing us to take up new research opportunities quickly and use them in clinical settings,” says Dr. Black, director of the Brain Sciences Research Program at Sunnybrook Research Institute.
At CeRIGT, researchers can spot irregularities in the brain’s blood vessels, from silent strokes that show up as little holes to white spots or patches that indicate other areas of damage, long before dementia sets in. White spots or patches (called white matter disease) are present in 95 per cent of those aged over 65 years.
People who have had silent strokes are much more likely to become cognitively impaired and to have a future stroke. Silent strokes are present in about 28 per cent of people over the age of 65, making them at least 10 times as common as clinically overt stroke.
One of the hallmarks of Alzheimer’s disease, the most common cause of dementia, is a buildup of plaque made of amyloid-beta peptides. In the inherited form of the disease, a genetic mutation causes overproduction of amyloid, and in later-onset disease, the brain’s inability to clear away amyloid is the main culprit in causing brain damage.
Small blood vessels in the brain (small arteries and veins) are susceptible to scarring as people age, causing resistance, back flow and leakage of blood fluid and proteins into the brain. This back-up can prevent amyloid removal from the brain along these vessels. Such amyloid build-up can make vessels burst and bleed, or cause a stroke through blockage of the arteries. It may also cause more amyloid plaques to deposit. “Believe it or not, Alzheimer’s disease is a key cause of hemorrhagic stroke, which is becoming more common in our aging society as we get better at treating hypertension, the more traditional cause. Amyloid is emerging as a major cause of brain hemorrhage in older people,” says Dr. Black.
Dr. Black’s team is conducting multiple intervention studies among stroke and dementia patients. “Our role in the Heart and Stroke Foundation Centre for Stroke Recovery is to provide the leadership in brain imaging and analysis on physical and cognitive aspects of recovery, including gait, balance and exercise, as well as in preclinical models. We are also investigating new ways to use infusion therapies with antibodies,” she says.
Sunnybrook is a leading hub for national and international collaboration in stroke and dementia research. Dr. Black is site director for the Heart and Stroke Foundation Centre for Stroke Recovery, a unique Canadian public-private partnership and nonprofit corporation. She also hosted the biennial meeting of the International Society of Vascular, Cognitive and Behavioural Disorders in Toronto this June. Together, researchers are pooling expertise to find new ways to halt or reverse silent brain disease.