Episode 13: Stroke, Dementia and Brain Health with guest Dr. Vladimir Hachinski
About Dr. Hachinski
Dr. Hachinski has transformed our understanding, diagnosis, treatment and prevention of the two greatest threats to the brain: stroke and dementia, and he co-discovered a link between Alzheimer's disease and stroke. He has published 18 books, including Treatable and Potentially Preventable Dementias (2018) and over 800 frequently-cited scientific articles. He received the Order of Ontario and was inducted into the Order of Canada. Dr. Hachinski is currently a Distinguished University Professor of Neurology and Epidemiology at Western in London, Ontario. He has received numerous awards and prizes and in 2018 was inducted into the Canadian Medical Hall of Fame.
Relationship between Stroke and Dementia
Stroke and dementia both arise from the same seabed of risk factors – e.g., high blood pressure, high cholesterol, physical inactivity, and unhealthy diet. Basically, having an unhealthy lifestyle puts you at risk for both (stroke and dementia). Moreover, experiencing a stroke will double your chance of developing dementia, because:
The damage the stroke does itself, and;
The stroke probably sets up inflammation, which in itself is harmful to the brain.
Clearly by preventing stroke, we can also prevent some dementias.
Incidence of stroke and dementia
In the year 2000, the Ontario government was persuaded to invest in a stroke strategy, which involved building more stroke units, more stroke prevention clinics and also creating public campaigns of risk control factors – e.g., high blood pressure. Dr. Hachinski’s group showed that if you went to a stroke prevention clinic (after experiencing a warning of a stroke), your chances of dying that year were 26% less. Dr. Hachinski figured that if the outcomes were better, that the incidence (number of cases per 1000) was probably dropping too. So, they looked at the incidence in Ontario over a 12-year period and found that the incidence of stroke decreased by 32% and that of dementia by 7%. It would be interesting to see whether other provinces that also have a stroke strategy have the same good results like that of Ontario, which may lead to actions preventing not only stroke but some dementias as well.
Warning signs of stroke
It’s very important to heed the following symptoms:
1. Sudden loss of speech (sudden meaning within seconds)
2. Sudden loss of the use of an arm or a leg
3. Sudden loss of vision in one or both eyes
4. Sudden staggering
These are all warning signs of a stroke. The fact that they disappear after minutes does not mean that the danger has disappeared. The above symptoms are emergencies. In fact, Dr. Hachinski coined the term ‘brain attack’, to let people know that these symptoms are emergencies. Unlike chest pain, the above warning symptoms are painless; but, regardless, people experiencing them need to seek immediate medical help.
To learn more about stroke, read Stroke: A Guide to Recovery and Prevention, a book written by Dr. Hachinski with his daughter Larissa to increase public awareness about stroke.
How much of stroke is preventable?
Ninety percent (90%) of stroke is preventable. There are several pieces of evidence in support of this fact, one of them is from the Global Burden of Disease. Another source of evidence involves a study, which looked at several countries to see what proportion of patients has treatable risk factors. As it turns out, it is 90%.
Effects of Air Pollution
At the global level, up to one-third (1/3) of strokes can be attributed to air pollution. Some might immediately say that’s a problem of New Delhi, Beijing or Mexico City. But, keep in mind that these continents are bound by the jet currents that go across the oceans. The biosphere gets mingled and consequently, what happens in Beijing matters in London, Ontario. We have known for a long time that air pollution damages the lungs, because you’re breathing in these particles and they cause inflammation. But now, research is starting to show that air pollution is a risk factor for heart disease, stroke and dementia. In fact, there is a Canadian study that showed that the closer you live to a major highway, the greater your risk of developing dementia.
Lifestyle Factors that can Help Prevent Dementia
If we look at identical twins (exact same genes), if one develops dementia, the chance of the other twin also developing dementia is only 50%. In other words, half of the inheritance is modifiable. Moreover, if you have the APOE4 gene (genetic risk factor for dementia) and high blood pressure, it multiplies and magnifies your risk of developing dementia. However, the good news is that the people who have this bad gene benefit the most from lifestyle modification. Clearly, the advice is that everybody should have a healthy lifestyle; but, if you have a bad family history, you will gain more - in terms of protection against developing dementia – when you engage in healthy lifestyle behaviours (e.g., exercise, healthy diet and controlling your blood pressure).
Blood Pressure and Dementia
Amyloid is a protein that occurs normally in the brain. The difficulty is that sometimes it splits in the wrong place, which produces beta amyloid (a protein that is toxic to the brain). People who develop dementia often have amyloid deposition, which tends to accumulate in the brain (and are called senile plaques). Other characteristics of people who develop dementia is that they often have depositions of tangles (made up of a protein called tau) in their brain cells, which damages neurons. It turns out that having high blood pressure accelerates the deposition of amyloid (which we know is bad for the brain). The good news is that when blood pressure is controlled the amyloid and tau depositions are slowed. In this way, controlling your vascular risk factors could also decrease your chances of experiencing neurodegeneration (from amyloid and tau deposition) that could result in dementia.
Importance of Controlling Blood Pressure
A study called Sprint showed that a lower blood pressure is better for the brain. Of course, we shouldn’t lower blood pressure too quickly (especially in older adults); but, probably, the blood pressure targets that we are aiming for (140/90) is too high. Even for the higher standard of 140/90, not enough people are well controlled. Some people don’t even know if they have high blood pressure, because they don’t even measure it. It is important that we remember that controlling blood pressure does not just involve taking pills. Keeping in physical shape and being physically active is also important. Having a good diet and avoiding food with high salt content is also important. Some people can control their blood pressure with lifestyle (e.g., diet and exercise), but most people do require some medication. Of note, high blood pressure if a very common condition. In fact, by the time people reach their 70s, around 2/3s of people have high blood pressure (by the current definition). So, this is one of those areas where we have a lot to gain – by preventing stroke, reducing dementia, lowering the risk for the development of some kidney diseases, and even minimizing the risk of some eye diseases (high blood pressure is bad for the eyes as well). Luckily, we have Hypertension Canada, which has done some innovative things – including adding blood pressure devices in pharmacies; so, anybody can go there to get their blood pressure measured, and if it’s high, they can get advice from the pharmacist and visit their family doctor. These blood pressure devices have made quite a difference in helping more people to have their blood pressure controlled.
White Matter Inflammation and Dementia
Mostly half of the human brain is made out of white matter (responsible for the speed at which signals are transmitted in our brains). White matter is very delicate. It receives less blood flow than the grey matter. Changes in the white matter of the brain is one of the first things to go wrong long before you show outward signs of cognitive impairment. Dr. Hachinski calls it “White Matter Changes – Red Flags”. In other words, white matter changes are an early warning system of trouble ahead. Specifically, if you have white matter changes in your brain, you’re more likely to have a stroke and you’re more likely to have dementia. One of Dr. Hachinski’s colleagues, Dr. Shawn Whitehead, observed in animal models of Alzheimer’s disease, that one of the earlier changes in the brain is inflammation of the white matter. Dr. Whitehead found that in animals with amyloid (brain pathology associated with Alzheimer’s disease) the inflammation following an induced stroke was much bigger than in animals that did not have the amyloid; but, by using anti-inflammatory agents, he was able to reduce the damage and decrease the cognitive impairment experienced by the animals.
White matter inflammation is measured by a very special technique called “positron emission tomography” – which requires radio isotopes. Measuring white matter inflammation is not an easy thing to do in humans. Some interesting work by Dr. Alexander Thiel looked at brain inflammation following stroke. He found that the cognitive status at 6-months correlated better with inflammation of the brain than with the original cognitive status.
While it’s hard for research to directly link lifestyle factors to healthy white matter in the human brain, what we do know is that people with a healthier lifestyle (e.g., proper exercise and diet) show fewer white matter changes and optimizes the function of the white matter.
Book: Treatable and Potentially Preventable Dementias
The book “Treatable and Potentially Preventable Dementias” by Dr. Hachinski (editor) is meant to be a practical guide for physicians to help prevent, delay or ameliorate cognitive impairment. This book is published by Cambridge University Press and is available where books are sold.
Future Directions
The Western Brain Institute has started a program on Great Ideas. We have proposed an idea to look across Canada to explore whether preventing stroke also prevented some dementias. Dr. Hachinski and his team are also interested in surveying all of the risk factors of dementia in a very comprehensive way. So far, we have talked about two sets of risk factors:
Environment
Individual risk factors
But there are other factors - including social factors and economic factors. For example, where you live and what access you have to healthcare impact your risk of developing dementia.
So, Dr. Hachinski and his team want to do a very comprehensive survey to look at what is happening in terms of the prevalence of dementia across Canada. They will also be working with economists to look at what can be done in communities to reduce dementia risk. If we – as a society - continue to do the same thing, this has a cost. In other words, inertia other costs. So, what Dr. Hachinski hopes to do is to produce a cost-effective model that could be applied and to also work with organizations whose mission is prevention – e.g., BrainShape, Alzheimer’s Society of Canada, Hypertension Canada, etc.
Dr. Hachinski wants to start a study by engaging the people who are likely to implement these policies, so that when they have the results there's some chance of the findings actually being implemented.
The other thing Dr. Hachinski wants to do is take an inventory of dementia prevention in Canada. For example, the Heart & Stroke Foundation or Alzheimer’s Society of Canada: What programs do they have related to prevention? How much does it cost? How effective are the programs? The goal of this work would be to identify gaps and overlaps. This would probably be the first time that such a comprehensive study has been done anywhere - not just in Canada.
To learn more about Dr. Hachinski and the work he is doing on stroke and dementia prevention, you can visit his Wikipedia page by clicking here.