Rising Blood Pressure, Declining Memory

Dementia risks were higher among people who had high blood pressure either in middle age or old age

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) High blood pressure is tied to greater risks of stroke and heart attack. But high blood pressure also may affect people in areas that may not seem so obvious, including their mental capabilities.

A study of thousands of men and women in Iceland has concluded that having high blood pressure in middle age or old age may raise the risks of damaging the structure of the brain and its ability to remember and reason.

Such damage was evident even in older people who previously had high blood pressure but later developed low blood pressure.

"Follow a diet and lifestyle that promotes healthy blood pressure."

Lenore J. Launer, PhD, of the National Institute on Aging in Bethesda, MD, was this study’s lead author.

This study's research team probed the health of 4,057 individuals from Reykjavik, Iceland, who had been enrolled in Age, Gene/Environment Susceptibility (AGES), part of the Reykjavik Study. That study by the Icelandic Heart Association was conducted between 1967 and 1996 and between 2002 and 2006.

At the start of the study, no participants had dementia, a disorder marked by loss of memory and the ability to think and reason well. Alzheimer's disease is the most common form of dementia.

At the start of this investigation, the participants were 50 years old, on average, but ranged from 33 years to 75 years old. At the end of this investigation, study participants were 76 years old, on average, but ranged 66 years to 95 years old.

At the study’s beginning and end, the researchers analyzed whether changes occurred in participants’ brains. These researchers used magnetic resonance imaging to scan those brains and measure potential damage to its small vessels and changes in brain size.

The researchers also tested, and then retested, the participants’ memory and thinking by giving them a standardized examination to measure those cognitive skills.

Based on test results, these researchers concluded that study participants who developed high blood pressure in old age but did not have high blood pressure during middle age were at higher risk for developing brain lesions and experiencing minor bleeding on the brain. Specifically, those who had high blood pressure in old age but not during middle age were 50 percent more likely to have brain lesions and bleeding than older study participants with lower blood pressure.

Bleeding on the brain can cause pressure that reduces brain size and keeps the brain from functioning normally.

The researchers also found that participants who had high blood pressure in middle age but low blood pressure in old age had a shrinkage in the size of their brain. Their scores on the memory section of that standardized test dropped by 10 percent between middle age and old age.

“Older people without a history of high blood pressure but who currently have high blood pressure are at an increased risk for brain lesions, suggesting that lowering of blood pressure in these participants might be beneficial,” Dr. Launer said in a press statement.

As for older persons who previously had high blood pressure but whose blood pressure lowered, Dr. Launer said such a change not only raised the risk that their memory and thinking would be impaired, but could also be linked to “more extensive organ damage.”

Blood pressure that is too low deprives the body of necessary blood flow. That abnormally decreased blood flow not only can harm the brain but also such organs as the heart. Severely low blood pressure can result in fainting, heart attack and major infection, among other problems.

A total of 59 percent of this study's participants were women. Men in this study were more likely than women to have such co-existing illnesses as diabetes, heart failure and other cardiovascular problems. Men also took more medication to control high blood pressure, the researchers wrote.

This study was published online June 4 in Neurology.

The National Institutes of Health, the National Institute on Aging, the Icelandic Heart Association, the Icelandic Parliament and Alzheimer Netherlands funded this study.

The researchers reported that they had no financial investments or other ethical conflicts that could affect study design, outcome or analysis.

Review Date: 
June 3, 2014
Last Updated:
June 5, 2014