Low Blood Pressure Tied to Cognitive Problems

Study finds higher risk in elderly who have heart failure

MONDAY, Dec. 10, 2001 (HealthDayNews) -- Having a sound mind as you get older could depend on your blood pressure, says new research.

Scientists have known for some time that congestive heart failure, a condition in which the heart can't pump enough blood to the body's organs, is linked to cognitive impairment in older patients.

Now, a large-scale Italian study suggests for the first time that low blood pressure raises the risk of cognitive dysfunction -- problems with attention, memory or simple math skills, for example -- in elderly patients with heart failure.

The findings appear in the Dec. 10 issue of the journal Neurology.

"It has not been appreciated up to now that there is a link between poor heart function and … cognitive impairment," says Dr. Patrick Pullicino, the co-author of an editorial in the journal accompanying the Italian study. "This adds to the weight of evidence that, particularly in elderly people, when the heart is not working properly, it does affect cerebral function."

In previous studies, researchers from the Catholic University of the Sacred Heart in Rome had noticed that many cases of cognitive impairment in older patients were associated with congestive heart failure. Although other studies had suggested a link between low blood pressure (hypotension) and cognitive problems, there had been few studies of this phenomenon in older patients.

"I wanted to see whether in a general population of elderly [people], there was an association between hypotension and cognitive impairment," says lead investigator Dr. Guiseppe Zuccalà, the chairman of the university's gerontology department.

Zuccalà's team recorded blood pressure levels and scores from standardized mental function tests of 1,583 elderly patients with heart failure who were admitted to 81 different Italian hospitals between 1995 and 1997. They compared these to test results from 12,052 people of roughly the same age who didn't have a heart condition.

The mental function tests involved such questions as giving your age, counting backwards from 20 to 1, or recalling the year in which World War I began.

After ruling out the potential effects of various medications or other diseases, Zuccalà and his colleagues found that 26 percent of the patients with low blood pressure showed signs of cognitive impairment, compared to 19 percent of the group without heart failure.

"We observed that this association was only valid for people who have heart failure," says Zuccalà. "[Low] blood pressure was associated with cognitive impairment independently of any other factor."

"The main type of impairment was in attention and mathematical calculation," he says, adding that similar levels of dysfunction were found in both men and women.

Although this study could not determine the cause of this link, the researchers suspect that decreased blood flow (hypoperfusion) through the brain could potentially be causing neuron dysfunction or death, leading to cognitive impairment.

It's not known whether oxygen or some other crucial nutrient is reduced in patients' brains, but Zuccalà says that some studies have suggested that heart failure causes a condition called white matter low attenuation, or subcortical dementia.

The team has found abnormal brain metabolism in patients with advanced heart failure who were waiting for a heart transplant. Zuccalà says that studies have shown that heart transplants or pacemaker implantation procedures that improve cardiac function can reduce or even reverse hypoperfusion.

However, he cautions that chronic hypoperfusion can cause irreversible changes in the brain, making early treatment crucial.

"We believe that it is important when you treat very old persons to monitor cognitive function, because excessive hypotension might damage their cerebral function," he says.

"We propose that simple testing of cognitive dysfunction might [reveal] this problem at the early stages, so you can intervene by avoiding excessive hypotension or by improving cardiac function in these patients," he adds.

The aging face of the Western population makes this a big issue, Pullicino says. "Cardiac failure is a huge problem," he notes. "There are 5 million [Americans] with it, and as we go into this century, we have increasing numbers of elderly people."

As the elderly population increases, the numbers of older patients with heart failure will also rise. "Estimates of 20 million have been put forward," Pullicino says.

Some experts are beginning to call this phenomenon circulatory dementia, he says, adding that it may interact with Alzheimer's disease or other neurological conditions to make them worse.

"There are a lot of elderly patients with heart failure," he says. "This is an under-recognized cause of cognitive dysfunction in the elderly."

But he stresses that it is potentially treatable, although more studies are needed to determine whether drugs like angiotensin-converting enzyme (ACE) inhibitors could increase blood flow to the brain and improve cognitive function in older patients with heart failure.

"Current therapies for dementia have only limited effects in terms of time and results," Zuccalà says.

He suggests that physicians need to take a holistic approach to treating older people by considering their cardiovascular, neurological and psychosocial well-being.

"It's very important to prevent cognitive impairment," he adds. "If you only try to treat a single function or organ, you might have very poor results."

What To Do

Find out about congestive heart failure from the American Heart Association, or check out this information on hypotension from Wellbeing.com.

The Heart Center Online also provides information about ACE inhibitor drugs.

SOURCES: Interviews with Giuseppe Zuccalà, M.D., chairman, department of gerontology, Catholic University of the Sacred Heart, Rome; Patrick M. Pullicino, M.D., Ph.D., chairman, department of neurosciences, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark; Dec. 10, 2001 Neurology
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