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Hypertension in middle-aged and older adults tied to cognitive decline

Reuters Health - 14/12/2020 - High blood pressure in both older and middle-aged adults is associated with cognitive decline, even when hypertension onset is fairly recent, a new study suggests.

In an analysis of data from more than 7,000 Brazilian adults given two cognitive tests over an average of nearly four years, researchers found that hypertension, prehypertension, and age at diagnosis were all independently associated with cognitive decline. But the amount of time a person had hypertension did not significantly impact the progression of cognitive decline, according to the report published in Hypertension.

Moreover, among individuals with diagnosed high blood pressure, those with uncontrolled hypertension showed a more accelerated decline in memory as well as global cognitive scores compared to those with controlled hypertension.

"We initially anticipated that the negative effects of hypertension on cognitive function would be more critical when hypertension started at a younger age, however, our results show similar accelerated cognitive performance decline whether hypertension started in middle age or at older ages," said study coauthor Dr. Sandhi M. Barreto, a professor of medicine at the Universidade Federal de Minas Gerais in Belo Horizonte, Brazil, said in a statement. "We also found that effectively treating high blood pressure at any age in adulthood could reduce or prevent this acceleration. Collectively, the findings suggest hypertension needs to be prevented, diagnosed and effectively treated in adults of any age to preserve cognitive function."

The authors did not respond to a request for comment.

Dr. Barreto and her colleagues analyzed data from an earlier longitudinal study, ELSA-Brasil, a multicenter cohort that included 15,105 civil servants aged 35 to 74. Data in the analysis came from two participant study visits, one between 2008 and 2010 and the other between 2012 and 2014.

The study focused on the 7,063 participants (mean age at baseline 58.9) who had repeat cognitive function tests, which were given only to those aged 55 and older at the time of the second visit.

In all, 22% of participants included in the current analysis had prehypertension (systolic blood pressure between 121 and 139 mmHg and diastolic blood pressure between 81 and 89 mmHg) and 46.8% had hypertension (systolic blood pressure of 140 mmHg or higher and diastolic blood pressure of 90 mmHg and above).

Researchers found that hypertension and prehypertension at baseline were associated with declines in global cognitive score; being hypertensive was associated with reduction in memory test scores; and prehypertension was associated with reduction in fluency test score. Hypertension diagnosis at age 55 or older was associated with lower global cognitive and memory test scores, and diagnosis before 55 was associated with lower memory test scores.

"In addition to other proven benefits of blood pressure control, our results highlight the importance of diagnosing and controlling hypertension in patients of any age to prevent or slow down cognitive decline," Dr. Barreto said in the statement. "Our results also reinforce the need to maintain lower blood pressure levels throughout life, since even prehypertension levels were associated with cognitive decline."

The new study adds to growing evidence that hypertension can harm cognition, said Rebecca Gottesman, a professor of neurology and epidemiology at the Johns Hopkins University School of Medicine in Baltimore. "In general, this study supports others showing high blood pressure, even when it's mild, is associated with worse cognition and decline. What this adds is that there is worse cognition not just in those who develop hypertension in middle-age, but also in those who develop it when they are older."

While it's not known exactly how high blood pressure hurts the brain, "there is good evidence from animal studies that suggests that hypertension may lead to a thickening of the small blood vessels in the head," Gottesman said. "Also, over time it can affect the blood-brain barrier, so maybe more toxins get in or the brain might not be able to do as good a job of getting rid of toxins. There are a lot of hypotheses." Recent research has suggested that aggressively lowering blood pressure may protect the brain, Gottesman noted.

"I think the most important aspect of this manuscript is the fact that exposure to adverse blood pressure levels is impactful not only for heart health, but this is now advancing our understanding for brain health, said Dr. Sadiya S. Khan, assistant professor of medicine at Northwestern University's Feinberg School of Medicine in Chicago.

"Cognitive function decline at this very early age may be an important harbinger of dementia," he said in an email. "Importantly, this may be a critical contributor to disparities in cerebrovascular disease and dementia in the U.S. Prevention and control of blood pressure must start earlier in the life course for greatest benefit."

SOURCE: https://bit.ly/3oSqRxK Hypertension, online December 14, 2020.

By Linda Carroll

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