The deterioration of mental ability associated with aging — such as memory loss and dementia — has many causes, including stroke and Alzheimer's disease.
But the screening tools commonly used by researchers and clinicians tend to take an either/or approach: Tests for Alzheimer's probe almost exclusively for signs of memory loss, while tests for stroke ignore the subtle changes in understanding that can be a sign of much more serious problems to come.
But that's about to change now that leading researchers in Canada and the United States have agreed to a common set of tests and standards to measure cognitive impairment.
“This is a Rosetta Stone,” said Vladimir Hachinski, a professor of neurology at the University of Western Ontario in London, Ont. (The Rosetta Stone is a bilingual tablet that was the key to deciphering ancient Egyptian hieroglyphics.)
“People working in different fields will now be able to speak the same language,” he said.
More important, Dr. Hachinski said, the change should allow for earlier diagnosis and treatment, particularly for people who suffer from so-called silent strokes, which cause significant brain damage but do not necessarily produce tell-tale symptoms like numbness and loss of speech.
The new standards are published in Tuesday's edition of the medical journal Stroke.
According to the paper, one in three of people can expect to suffer from stroke, dementia or both if they live to an average life expectancy.
Two-thirds of people who have a stroke will suffer some degree of cognitive impairment, and another one-third will develop full-blown dementia.
Similarly, at least one-third of people with Alzheimer's disease will show signs of vascular damage. Stroke and Alzheimer's (and related dementias) also have common risk factors such as age, high blood pressure, smoking and poverty.
“Obviously, there is a lot of overlap,” Dr. Hachinski said. “But, until now, scientists working in the field of vascular disease and the field of dementia have not had a common language.”
The new standards, developed jointly by the Canadian Stroke Network and the U.S. National Institute for Neurological Disorders and Stroke, set out diagnostic criteria ranging from questions to be asked about family history through to interpretation of tests such as computerized tomography scans.
The article stresses, however, that this is just a starting point and that more research is required to refine the approach.
Dr. Antoine Hakim, CEO and scientific director of the Canadian Stroke Network, said it is difficult to overstate the importance of the common approach and the ability it will give physicians to make an early diagnosis.
