A major medical study in the United Kingdom involving 20,000 participants has found people with high diastolic blood pressure are more likely to suffer from cognitive impairment (or memory loss) compared to people with normal diastolic readings.

Cognitive impairment occurs when a person has trouble remembering, learning new things, concentrating, or making decisions that affect their everyday life, said the U.S. Centers for Disease Control and Prevention (CDC). Cognitive impairment ranges from mild to severe.

Severe levels of impairment can lead to losing the ability to understand the meaning or importance of something and the ability to talk or write.

According to a medical study published recently in the journal Neurology, high blood pressure is linked to memory problems in people over 45. High blood pressure is defined as a reading equal to or higher than 140/90 or taking medication for high blood pressure.

The study found that for every 10 point increase in the diastolic reading, the odds of a person having cognitive problems was seven percent higher. It said this result was valid after adjusting for other factors that might affect cognitive abilities. These factors included age, diabetes, exercise level, smoking status, education and high cholesterol.

The study involved people age 45 and older across the United Kingdom that participated in the Reasons for Geographic And Racial Differences in Stroke (REGARDS) Study and had never had a stroke or mini-stroke.

Of the 20,000 total participants in REGARDS, 1,505 (7.6 percent) had cognitive problems. A further 9,844, or 49.6 percent, were taking medication for high blood pressure.

"It's possible that by preventing or treating high blood pressure, we could potentially prevent cognitive impairment, which can be a precursor to dementia," said study author Dr Georgios Tsivgoulis, MD, of the University of Alabama at Birmingham and a member of the American Academy of Neurology (AAN).

More than one in four people live with cognitive impairment with in the UK. More than 16 million people in the United States live with this condition. Many people don’t realize they have cognitive impairment because the symptoms are hard to spot.

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How does high blood pressure cause cognitive impairment? Research reveals high diastolic blood pressure leads to weakening of small arteries in the brain that can result in the development of small areas of brain damage.

Dr. Tsivgoulis said more research is needed to confirm the relationship between high blood pressure and cognitive impairment.

"The REGARDS study is one of the largest population-based studies of risk factors for stroke. 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," noted Dr Walter J. Koroshetz, MD, deputy director of NINDS and Fellow of the AAN.

"The National Institutes of Health is now organizing a large clinical trial to evaluate whether aggressive blood pressure lowering can decrease a number of important health outcomes including cognitive decline.”