They said people with high diastolic blood pressure — high readings on the bottom number of the blood pressure reading — were more likely than those with normal readings to have problems with memory and thinking called cognitive impairment.

The study, published in the journal Neurology, is the largest to look at the link between high blood pressure and memory problems.

'It's possible that by preventing or treating high blood pressure, we could potentially prevent cognitive impairment, which can be a precursor to dementia,' Dr. Georgios Tsivgoulis of the University of Alabama at Birmingham, who led the study, said in a statement.

Researchers studied nearly 20,000 people 45 and older who had never had a stroke or mini-stroke — a common cause of memory problems. More than 7 percent had memory problems, and nearly half were taking medication for high blood pressure.
 
High blood pressure is defined as a reading of 140/90 or above.

For every 10 point increase in the bottom blood pressure reading, the odds of a person having cognitive problems increased by 7 percent, the researchers found.

The results held even after being adjusted for other factors that can mar thinking, such as age, smoking status, exercise level, education, diabetes or high cholesterol.

'These latest data suggest that higher blood pressure may be a risk factor for cognitive decline, but further studies will be necessary to understand the cause-effect relationship,'

said Dr. Walter Koroshetz, deputy director of the National Institute of Neurological Disorders and Stroke, which funded the study.

Koroshetz said the National Institutes of Health is organizing a large clinical trial to see if aggressive measures to lower blood pressure can lower the risk of memory problems.

According to the American Heart Association, about one in three adults in the United States has high blood pressure.

Because there are no symptoms, many people have high blood pressure for years without knowing it.

Uncontrolled high blood pressure can cause stroke, heart attack, heart failure or kidney failure. — Reuters