Gregoria Collados Hall

Stroke patient Gregoria Collados Hall talks with Dr. Shyam Prabhakaran at Rush Medical Center. Researchers discovered that patients with high blood pressure and other risk factors for stroke are more likely to develop thinking or reasoning problems than otherwise healthy individuals. (Heather Charles/Chicago Tribune)

Doctors long have cautioned patients about the consequences of uncontrolled high blood pressure, including heart attacks, strokes and kidney failure.

Now they can add cognitive decline to that list, after researchers discovered that patients with high blood pressure and other risk factors for stroke are more likely to develop thinking or reasoning problems than otherwise healthy individuals.

The link between cognitive decline and hypertension will put even more emphasis on prevention, said several stroke specialists.

"This takes the disease to an even earlier point, that if you don't change these factors or modify or control them, you are likely going to develop some cognitive issues, even if you never develop stroke," said Dr. Shyam Prabhakaran, director of the Stroke Program at Rush University Medical Center. "The impact of this study is really directly at primary care prevention."

Prabhakaran said the study was impressive because of the large number of participants and their multiethnic backgrounds.

The study, published in the Nov. 8 issue of Neurology and funded by the National Institutes of Health, followed 24,000 individuals with no prior history of cognitive impairment or stroke. Participants were tested, using the Framingham Stroke Risk Profile, as well as a simple cognitive health screening over about four years. Individuals are at higher risk, according to the profile, if they are male (though more women die of the disease), black or Hispanic, 55 and older, have high blood pressure or hypertension, heart disease, diabetes, a cholesterol imbalance or obesity.

Researchers found that 1,907 participants, or 8 percent, showed cognitive impairment. Being male, black, having less than a high school education, left ventricular hypertrophy (muscle tissue enlargement of the wall of the left ventricle) and high systolic (first number in a blood pressure reading) blood pressure were related to the decline.

Prabhakaran said he suspected that an even higher percentage might have shown cognitive decline if the researchers had used a more in-depth test.

Frederick Unverzagt, a professor of psychiatry at the Indiana University School of Medicine in Indianapolis and lead author of the study, said in a news release that the individuals with cognitive decline might have had silent strokes or other subclinical changes affecting the brain's blood supply. Silent strokes have no obvious physical symptoms but place an individual at high risk for a clinical stroke.

The findings were part of the study known as Reasons for Geographic and Racial Differences in Stroke, or REGARDS, which is sponsored by the NIH and follows ethnically diverse individuals 45 and older throughout the United States.

Sean Ruland, director of the Neurocritical Care and Stroke at the University of Illinois Hospital and Health Sciences System, who also heads the Vascular Neurology Group at Resurrection Medical Center, said the study "reinforces the message that there are more reasons to control blood pressure than just heart attack and stroke."

"The laundry list of what hypertension does to a body that can affect you over time is ever growing."

But Ruland said the findings could have broader implications.

"The fact that black race and lower level of educational attainment were predictive represents a bigger public policy message, especially as we debate the potential impact of recent health care reform legislation," he said.

The study also can help convince patients that major health problems can stem from uncontrolled blood pressure, according to Dr. Hamad Farhat, a NorthShore University HealthSystem neurosurgeon and expert in cerebrovascular neurosurgery and carotid disease. Farhat said some patients don't take their blood pressure medication because they feel sick from the subsequent drop in blood pressure or they feel fine and think they don't need medication.

Doctors should also be on the lookout for cognitive troubles in patients with high blood pressure, since the changes can be subtle and might go unnoticed, even by family members, said Farhat.

"When we objectively test them using a cognitive scale, this is when we find an actual difference," said Farhat.