What’s the link between these two frightening health issues? A top scientist explains what you need to know.
Researchers have proven that there’s a connection between stroke and vascular dementia.
But it’s a relationship that’s only beginning to be understood.
The 2016 Stroke Report from the Heart and Stroke Foundation reveals that having a stroke more than doubles your risk of developing dementia, and that one in three Canadians will develop stroke, dementia or both.
The key to this connection is a type of dementia known as vascular dementia. How is it related to stroke, and what can you do to protect yourself? For answers we went to Dr. Antoine Hakim, a stroke specialist and an emeritus senior scientist at the Ottawa Hospital Research Institute.
How is vascular dementia related to Alzheimer’s?
Vascular dementia is a loss in brain function that occurs when the blood vessels that feed a region of the brain become blocked or begin to bleed. Your brain only makes up two to three per cent of your body weight, but it consumes more than 20 per cent of the energy that you produce; it’s incredibly dependent on having a constant blood supply. So when the pathways that carry that blood through the brain close up, brain cells are deprived of oxygen and they die.
The symptoms of someone experiencing vascular dementia will vary depending on the region of the brain that’s been injured. Common symptoms include word finding and comprehension problems or visual-spatial difficulties, as opposed to memory loss which is more often an early symptom of Alzheimer’s disease. People who experience vascular dementia may have trouble retrieving information they’ve learned before. Multitasking, planning, organizing and problem solving can become a challenge, as can the ability to pay attention and concentrate for long periods.
Vascular dementia is also physically different from Alzheimer’s disease. When doctors examine the brain of a patient with Alzheimer’s disease they see two abnormalities: clumps of damaging beta-amyloid proteins in the spaces between brain cells, and tangles of tau protein that build up within the patient’s brain cells.
When they examine the brain of a patient with vascular dementia they see blood vessels, small and large, that have blocked up and closed, depriving a brain region of its blood supply and causing scarring. That interrupts communications among different brain regions.
An increasing number of people will experience what’s called mixed dementia, with symptoms that resemble vascular dementia, Alzheimer’s disease or a combination of the two.
What’s the connection to stroke?
Stroke happens when blood supply to a part of the brain is cut off. Most strokes are caused by a blood clot blocking a blood vessel (ischemic stroke). A smaller percentage is caused when a blood vessel in the brain ruptures (hemorrhagic stroke). In both cases, the cells in the affected area are starved of oxygen within seconds. For every minute after stroke, 1.9 million brain cells die – cells that may control your ability to speak, move, remember, talk and write.
Smaller events in the brain can also contribute to cognitive decline. A covert stroke is a stroke so mild that the affected person has no noticeable symptoms. But it can leave the brain injured, as can micro bleeds in the brain (known as small vessel disease). Typically these smaller events are only detected after the fact, say by a brain scan in someone who is experiencing cognitive impairment.
What are the risk factors?
Vascular dementia, stroke and cardiovascular disease all share the same controllable risk factors. High blood pressure is the biggest concern. Then we can look at atrial fibrillation, diabetes and the other usual risk factors for heart disease and stroke: high cholesterol, smoking, obesity, poor diet, physical inactivity, stress.
All of these contribute to the development of vascular dementia but high blood pressure is at the top of the list.
Stroke more than doubles your risk of dementia. If you take action to reduce your risk of stroke, including covert stroke you’ll also lower your risk of developing vascular dementia, and even heart disease.
Why is high blood pressure so dangerous?
High blood pressure or hypertension is the number one risk factor for stroke. You can’t feel it – that’s why it is often called a silent killer. Left untreated, high blood pressure forces a blood vessel to react in two ways. First, the vessel thickens up its walls. That’s called atherosclerosis. Then it constricts, to diminish the likelihood of bursting. Together this reduces the flow of blood to the brain and can potentially damage brain tissue.
What can you do to lower your risk of developing dementia?
Number one is measure your blood pressure once a week, when you’re at home and not feeling stressed. Write down the date and your numbers and then take that table of data to your physician. “White coat syndrome” happens to a lot of people, meaning they feel anxious at the doctor’s office and show a higher blood pressure reading. Unfortunately, this is often used as an excuse to ignore hypertension. So we recommend measuring your blood pressure when there are no white coats around.
And then focus on reducing your other risk factors. Things like eating right, moving more, lowering your cholesterol, and quitting smoking all help lower your risk of developing stroke, vascular dementia and heart disease.
Aside from reducing your risk factors, is there anything specific you can do to protect your brain?
You can look at how you’re maintaining your cognitive reserve. That’s your brain’s resilience and ability to cope with damage by using different pathways to perform tasks. You can improve your cognitive reserve by exercising your brain more. Challenge yourself to remember new things, try new skills, and develop new tricks. Solving Sudoku puzzles or completing brain training games isn’t enough. Our brains like variety. Doing one type of exercise may help that part of your brain to function better but other brain networks may also benefit from being activated by other activities.
Regular physical activity, particularly aerobic activity, can go a long way toward fighting cognitive decline. Activities that challenge your brain now and can help protect it later include:
- Learning a new language
- Committing new information to memory
- Travelling to a new place
- Trying a new hobby, especially one that involves body movements.
When you tease your brain with new information, exercise more, or reduce your smoking, your brain rewards you by opening up new blood vessels, new pathways to support these connections that you’re forming. This can help protect you from developing dementia later on.
- What risk factors can you change today? Take our free Risk Assessment to find out.