The stroke-dementia connection

By Laura Eggertson

Update (March 28, 2017): University of Ottawa neurologist Antoine Hakim has won the prestigious 2017 Canada Gairdner Wightman Award, given to a Canadian who has demonstrated outstanding leadership in medicine and medical science. The Gairdner Foundation cited Dr. Hakim’s work as being “critical to changing attitudes towards stroke, which went from being a devastating condition to one that is preventable, treatable and repairable.”

Once a week without fail, Dr. Antoine Hakim sits down, wraps a cuff around his arm and takes his blood pressure.

It’s a simple way to make sure he’s not at risk for hypertension (the formal name for high blood pressure), a condition that his 40 years of research and practice as a neurologist have convinced him contributes greatly to the development of dementia.

Vascular disease and dementia “talk to each other,” says Hakim, professor emeritus at uOttawa Faculty of Medicine and formerly University of Ottawa chair in neurology and director of neuroscience research at the Ottawa Hospital Research Institute.

The link between stroke and dementia was not always clear to Hakim. Initially, his research career concentrated on determining the causes of strokes and improving treatment for those suffering from them. In the mid-1980s, when he began working in the field at the Montreal Neurological Institute and McGill University, “stroke was a dismal condition,” Hakim says. “It really affected individuals and their families for the rest of their lives.”

But when Hakim came to the University of Ottawa in 1992, the tide was beginning to change on stroke research. He led a neuroscience research program that resulted in the creation of the Ottawa Stroke Consortium for Applied Research (OSCAR) and the Canadian Stroke Network.

The concentration of motivated researchers that Hakim helped to recruit soon achieved a breakthrough. He and his colleagues discovered that when a stroke occurred, only the cells in the centre of the area affected by the blood clot died immediately. Those outside the centre remained viable for a few hours. 

Game-changing drug

That knowledge helped lead to the development of a drug called tissue plasminogen activator, or tPA. The game-changing drug dissolves clots and restores the flow of blood to the brain — if patients receive it quickly enough after a stroke, before all the affected cells have died.

The national program Hakim led educated both the general public and doctors about the actions to take when a stroke occurs, the need to get to an emergency room quickly and the importance of administering tPA within a three-to-four hour window, the sooner the better. The campaign and the new treatment converted stroke into a preventable, treatable and repairable condition.

“Canada became a model of how to deal with stroke across the world,” says Hakim.

It was when he treated stroke patients who did not have access to tPA fast enough that Hakim and others made the connection between stroke and dementia. The patients would describe their difficulty in making cognitive decisions. “They would complain that their brain was in a fog,’’ he says.

Other research at the time revealed that small strokes block tiny blood vessels and can produce dementia, often without patients even knowing the strokes have occurred. 

For instance, Alzheimer’s disease, a form of dementia, is believed to occur when tangles or plaques of malformed proteins accumulate in neurons. The co-occurrence of small strokes means brain cells cannot clear these damaging proteins.

But people who have accumulations of these proteins may not develop dementia unless they have inherited the disease or have also developed vascular disease, Hakim says.

“We know that vascular disease alone, when it impacts the brain, will lead to dementia,” Hakim says. “That doesn’t mean that accumulating the proteins of Alzheimer’s disease is inconsequential, but we know that people can remain cognitively normal despite the presence of plaques and tangles in their brains.”

7 rules to ward off dementia

The relationship between stroke and dementia prompted Hakim’s current research. In his new book, Préservez votre vitalité mentale: 7 règles pour prévenir la démence, he passes along knowledge his patients and his own research have taught him about the underlying factors that drive stroke.

His first advice is to “build your cognitive reserve” by activating all areas of the brain, through activities that range from committing poems to memory to writing letters long-hand, reading old-fashioned maps and spelling words on our own, without depending upon smartphones to auto-correct.

The second rule is to avoid high blood pressure, which can result in vascular disease — this is why he tells people to invest in blood pressure cuffs. It’s important to monitor blood pressure, he says.

“Measure your blood pressure once a week,’’ he urges. “Write it down. Write the date — week in and week out. The higher number should not be above 120 when you are calm and relaxed.”

Eating healthy, non-processed food (he recommends the Mediterranean diet, which is heavy on fish, nuts and legumes), maintaining a healthy weight and exercising just hard enough each day to get out of breath are other critical prevention activities. Even moderate exercise will open blood vessels to support brain activity, Hakim says.

Getting enough sleep is also crucial, because, at night, brain cells are active in cleaning up damaged proteins, he says. Avoiding sadness and depression by staying socially connected is also vital.

Hakim is using his book, which will appear in English in 2017, to advocate for a national dementia strategy, which he hopes could incorporate policy tools such as taxes on soft drinks to reduce their consumption. By 2031, the Alzheimer’s Society of Canada estimates that close to one million Canadians will be living with dementia, and yet, Canada is the only G8 country without a strategy, he says.

“Decreasing the likelihood of dementia starts early,” Hakim says. “A lot of what we can do to prevent dementia is not expensive. We just have to have the will to do it.”

Main photo:
Dr. Antoine Hakim believes it is never too late to adopt behaviours that can protect brain health and decrease the risk of dementia. Photo: Peter Thornton