Washington, Feb 23 : Researchers at the University of Alabama in Birmingham have reported that older people with the highest risk of stroke are more likely to have the highest rate of cognitive decline as well, even if they never actually suffered a stroke.
The findings were reported at the American Stroke Association's International Stroke Conference 2008.
"We found that people at high risk of stroke, decline twice as fast as those persons considered at low-risk," George Howard, Dr.P.H., professor and chair of biostatistics at the University of Alabama in Birmingham and the principal investigator of the ongoing study, said.
Howard and his colleagues used the Framingham Stroke Risk Function (FSRF) assessment, in which risk factors are used to estimate the chance of having a stroke in the next 10 years.
The researchers found that those with the highest stroke risk also had an accelerated rate of cognitive decline.
"The difference in the annual rate of cognitive decline between a person with a 2 percent chance of a stroke in the next 10 years and a person with at 22 percent chance was 95 percent as great as the average rate of cognitive decline - suggesting that this difference in the risk of a stroke roughly doubles the normal rate of decline," Howard said.
These preliminary findings came from one of several studies conducted by REGARDS (Reasons for Geographic and Racial Differences in Stroke) researchers who analyzed cognitive data from 17,626 people (38.6 percent black).
The participants had never suffered a stroke and had at least two cognitive assessments.
The participants were an average age of 65.9 and had average systolic blood pressure of 127.9. 56 percent of them had hypertension; 19.3 percent had diabetes, 21.9 percent suffered from heart disease; 6.5 percent had left ventricular hypertrophy, and 13.1 percent smoked.
REGARDS' main goal is to understand the high stroke death rate in the Southern United States, sometimes called the Stroke Belt, and among black Americans
To test the participants' mental skills, researchers gave three common words to the participants during a phone call and later asked them to repeat the words.
"A lot of people couldn't remember the words. If you extrapolate these effects, our findings suggest that would be an average 8 percent larger increase in missed questions after 10 years in the high-risk group. That's a large difference," Howard said.
The researchers also identified three specific risk factors significantly linked to memory loss - high systolic blood pressure, diabetes, and left ventricular hypertrophy.
Diabetes was associated with about at 56 percent increase in the rate of cognitive decline while left ventricular hypertrophy was associated with about a 60 percent increase in the rate of decline.
Howard said that a 31 mm Hg-higher level of blood pressure was associated with a 29 percent increase in the rate of cognitive decline.
"Others have shown the Framingham Stroke Risk Function is related to cognitive decline. I believe we are the first to say it's because of these particular components," Howard said.
He called this conclusion a logical assumption, but said a clinical trial is required to confirm it.