Stroke Prevention Best Path to Dementia Reduction, Experts Say

Pauline Anderson

July 23, 2019

A global group of neurology experts has issued a call to action for a coordinated effort to reduce the incidence of dementia via stroke prevention.

Worldwide, neurologic disorders account for the largest number of disease-adjusted life years (DALYs). More than half of DALYs from neurologic disorders result from stroke and dementia.

Both conditions arise from similar treatable risk and protective factors, and growing evidence suggests preventing stroke can also prevent some dementias. About 90% of strokes are potentially preventable, as are some dementias.

Dr Vladimir Hachinski

"The evidence by now is overwhelming and incontestable" that stroke doubles the chances of developing dementia, Vladimir Hachinski, MD, professor of neurology and epidemiology at Western University in Canada and Vice President of the World Stroke Organization, told Medscape Medical News.

Hachinski, who coined the term "brain attack" and devised the Hachinski Ischemic Score that remains the standard for identifying a vascular component of cognitive impairment, is among 26 experts who met in Berlin, Germany to hammer out a plan of action.

These experts are authors of an article outlining their proposed strategy. The article was published online July 18 in Alzheimer's & Dementia.

Recommendations

The article reviews the epidemiology and pathophysiology related to stroke and dementia and includes recommendations for prevention.

The public, and even the medical profession, is largely unaware that the most common outcome of cerebrovascular disease is not stroke but cognitive impairment, said Hachinski.

He cited one study showing that for each identified clinical stroke, there are about five "silent" strokes where the patient has no symptoms and may not even be aware of the event's occurrence.

"But if you test these people, they have decreased processing speed, impairment in working memory, and impairment in executive function," Hachinski said.

In Canada, Hachinski's research group found that about 64% of those over age 65 who have a stroke will have some cognitive impairment, although not necessarily dementia.

There are two ways to try to prevent dementia, said Hachinski. The first is what he refers to as a "silver bullet approach," which involves searching for a drug to stop the accumulation of amyloid.

"We're a long way away from that because nothing has worked so far, and even if you find something today, it will probably be 5 or 10 years before it's implemented."

Hachinski emphasized that amyloid and tau proteins are not the only pathologies related to Alzheimer's disease (AD), and that the many interactive pathologies in aging require multimodal targeting.

The second way to attack the problem, which Hachinski calls "the golden pellet approach," involves implementing changes known to make a difference: treating high blood pressure, eating a healthy diet, and living in a healthy environment that incudes less pollution.

"With this approach, we can make a difference now," he stressed.

To that end, Hachinski wants to see the widespread establishment of stroke prevention clinics.

"Our group showed that if you have a threatened stroke and go to a stroke prevention clinic, chances of dying that year are decreased by 26%, and the good news was that it wasn't just sophisticated clinics like we have here at University Hospital; it was community stroke prevention clinics too."

Systematic Approaches Are Powerful

Stroke prevention initiatives in Canada and elsewhere have shown that systematic approaches reduce the incidence of stroke. The Berlin Manifesto authors believe this represents a path to dementia prevention.

The problem has been that neurologists have become so specialized — in either stroke or dementia — that these experts do not look at both conditions together, even though they share the same risk factors, said Hachinski.

Establishing prevention units doesn't have to involve a huge financial investment, just creative reorganization and dedicated staff with related expertise, he said.

"You don't have to build anything; just make sure one of the clinics is devoted to prevention, then you can prevent stroke and prevent dementia in a relatively cheap way. In other words, it's a good return for investment because it's such a prevalent problem," Hachinski said.

Dedicated prevention units don't even need to be staffed with neurologists — just capable experts such as internists and specially trained nurses, said Hachinski. "The key is to do things promptly."

A prevention clinic would treat high-risk patients with warning signs of a stroke such as transient ischemic attacks. The clinic would have access to tests, including brain imaging and carotid artery ultrasound, and be able to monitor for, and treat, atrial fibrillation (AF).

AF, noted Hachinski, is highly treatable and a main cause of stroke, particularly among the elderly. Other causes include atherosclerosis of the carotid artery and small vessel disease associated with high blood pressure.

The exact number of strokes that could be prevented with a system of prevention centers is unknown, but Hachinski said it would be "countless."

"Stroke is such a common problem that even a small difference would make a big difference in terms of outcomes," he noted.

Global Problem, Global Initiative

Hachinski contends that preventing stroke and dementia should be a global initiative. While the prevalence of dementia in the developed world is stable — maybe even declining as a result of improved risk factor control, societal conditions, education, and healthcare — this is not the case in developing countries.

"I suspect that part of this is urbanization," said Hachinski. "More people live in big cities where getting fast food is easy and cheap, and getting exercise is hard. And the problem of pollution is becoming highly prevalent."

Hachinski and coauthors determined that investigation of dementia in diverse settings, including a more global perspective, is crucial for a more comprehensive understanding of the condition and identification of novel solutions.

"Most of what we know about dementia derives from Caucasian populations, largely western Europe and North America," said Hachinski. "But most of the world is elsewhere; 61% is in Asia, for example."

A 70-year-old widower in North America who is in an accident or makes banking errors would be quickly picked up by the medical profession as having cognitive decline.

"But if that man lives in India with an extended family, his cognitive problems may be chocked up to grandpa getting old," and it would take a long time for these problems to come to medical attention, said Hachinski.

He noted that all major world organizations dealing with the brain and heart have committed to the joint prevention for stroke and dementia.

The paper includes recommendations, one of which is to create what Hachinski referred to as "a guiding catalyzing" group. "This would be people who are looking at what can be implemented now, and then also getting together the people who can do it," he said.

The group is also calling for an "integration" of all elements that contribute to stroke and dementia, said Hachinski.

"It's not simply personal risk factors, but also where you live, with whom you live, what you do, what you earn, and what your environment is like — these all contribute," he emphasized.

The unifying concept, he said, is that "without brain health, there is no health."

The group has formed a working group to take further steps, and is looking for funding opportunities "to begin preparing customized, cost-effective solutions for different parts of the world," said Hachinski.

Cross-Fertilization

Commenting on the Berlin Manifesto initiative for Medscape Medical News, Heather Snyder, PhD, senior director of medical and scientific operations at the Alzheimer's Association, said she is seeing more "cross-fertilization" of diverse specialists interested in dementia.

"Part of that is that as the science emerges it's becoming apparent that there are these linkages" between specialities, she said.

Snyder recently sat on a panel that included a cardiologist and a psychiatrist interested in vascular contributions to dementia.

The journal Alzheimer's & Dementia, as well as forums and meetings like the annual Alzheimer's Association International Conference (AAIC), raise awareness and provide opportunities "for the scientific community to come together, look at where the data is, what the science is, and look at it in an evidence-driven way to move us forward," said Snyder.

The Alzheimer's Association has supported research related to blood pressure reduction, which lowers stroke risk. Snyder noted that the Association has awarded funding to the SPRINT MIND 2.0 study, which will further investigate the impact of intensive blood pressure treatment on reducing risk of dementia.

The SPRINT MIND study, published earlier this year and reported by Medscape Medical News, was the first randomized clinical trial to show that intensive blood pressure lowering can significantly reduce the incidence of mild cognitive impairment (MCI), a known risk factor for dementia. People who develop dementia will first pass through the MCI stage.

Hachinski has disclosed no relevant financial relationships.  

Alzheimer's & Dementia. Published online July 18, 2019. Full text

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