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High blood pressure accelerates memory loss and other cognitive declines for middle-aged or older adults, even when it only goes up slightly and for a short time, new research shows.

Conversely, controlling high blood pressure slows the speed of cognitive decline, according to a study published Monday in the 91ÊÓƵ's journal . The study showed the age at which blood pressure began rising didn't matter.

"We initially anticipated that the negative effects of hypertension on cognitive function would be more critical when hypertension started at a younger age," lead investigator Dr. Sandhi M. Barreto said in a news release. But that wasn't the case.

Barreto, professor of medicine at the Universidade Federal de Minas Gerais in Belo Horizonte, Brazil, and his team analyzed blood pressure and cognitive information for more than 7,000 adults in Brazil. Their average age was 59 when the study began, and participants were tested over an average of four years for memory, verbal fluency and executive function, which includes attention, concentration and other factors associated with thinking and reasoning.

They found people with high blood pressure who weren't taking medication to lower it saw faster declines in cognitive performance than those without high blood pressure or whose blood pressure was controlled through medication. The speed in decline took place regardless of how long blood pressure stayed elevated or at what age it was diagnosed. Even those with prehypertension, a condition of slightly elevated blood pressure, saw a faster decline in cognitive function than those with blood pressure in the normal range.

"Our results reinforce the need to maintain lower blood pressure levels throughout life," Barreto said. "Collectively, the findings suggest hypertension needs to be prevented, diagnosed and effectively treated in adults of any age to preserve cognitive function."

According to , nearly half of U.S. adults – roughly 116 million people – have high blood pressure. Chronic high blood pressure, particularly in midlife, has been shown to contribute to cognitive decline and the risk for dementia. However, evidence regarding the impact of high blood pressure on cognitive function later in life has been less conclusive.

Based on these new results, "maintenance of good blood pressure control holds promise to prevent decline in cognitive abilities whether one is in middle age or older," said Dr. Philip B. Gorelick, a vascular neurologist in the department of neurology at Northwestern University's Feinberg School of Medicine in Chicago. He is a co-author of an AHA scientific statement .

"Elevation in blood pressure may cause damage to areas in the brain important to memory or other cognitive function," he said, "or may alter brain receptors that are necessary to assure normal cognitive function."

Gorelick, who was not involved in the new research, said a longer study that looked at the impact of high blood pressure on both cognitive decline and the development of dementia would help further understanding of how hypertension impacts the brain.

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