For patients with high blood pressure who hope to ward off dementia, doctors have the same advice for those looking to protect their hearts and kidneys: Go lower.
In a comprehensive new study, researchers found that driving down patients’ systolic blood pressure readings to a new lower target level reduced their risk of developing mild cognitive impairment, or MCI, by close to 20%. MCI is a decline in memory and thinking skills that is slight but noticeable, and it affects 15% to 20% of people older than 65.
For as many as half of those diagnosed with MCI, a diagnosis of dementia will come later.
The new research found that compared with subjects whose blood pressure control regimen was more relaxed, subjects whose blood pressure was more strictly controlled were 15% less likely to be diagnosed with MCI and subsequent dementia.
The new findings, presented last week at the Alzheimer’s Assn.’s International Conference in
Chicago, come a year after the American Heart Assn. and the American College of Cardiology
adopted a new target for those with hypertension. Physicians groups had long considered blood
pressure readings of 140/90 mm Hg to be an acceptable target for those with hypertension, but in 2017, they urged physicians to aim for 130/80 mm Hg in patients with high blood pressure.
The research suggests that there are powerful benefits to getting the first number in that reading — systolic blood pressure — to an even lower target: 120 mm Hg.
Systolic blood pressure is the amount of pressure in a person’s arteries during the contraction of her heart muscle. Because it is the highest pressure to which the blood vessels are subjected, systolic blood pressure is thought to have the most detrimental effect on the delicate capillaries that nourish the brain as well as the kidneys, heart and liver.
In large populations, lowering that reading to 120 already has been found to reduce rates of
cardiovascular disease and kidney failure. The new findings emerge from a clinical trial called SPRINT (Systolic Blood Pressure Intervention Trial), which began in 2010. After subjects had been followed for an average of just over three years, the trial was shut down early because the benefits of the lower systolic blood pressure goal in protecting people’s hearts were so clear.
In August 2015, a board of safety monitors said it no longer could justify maintaining some of the trial’s subjects at the systolic target level of 140 mm Hg.
“What SPRINT has shown is that what is good for your heart is also good for your brain,” said the study’s lead author, Dr. Jeff Williamson of Wake Forest Medical School, who presented the findings in Chicago.
Williamson called it “very encouraging” that even a brief period of more intensive blood pressure control would show such powerful protective effects for the brain as well. Had the trial run longer, he said, there’s reason to believe that even more cases of mild cognitive impairment and dementia might be prevented.
The trial’s 8,626 subjects ranged in age from 50 to 100. None had diabetes, but all were considered to be at increased risk for cardiovascular disease. After a year, those assigned to have their blood pressure treated to the stricter target had achieved an average systolic blood pressure reading of 121.4 mm Hg. Those assigned to the standard treatment group had an average systolic blood pressure reading of 136.2 mm Hg.
Dr. Lon Schneider, an Alzheimer’s specialist at USC’s Keck School of Medicine, hailed the findings.
But he suggested that the average age of the trial’s subjects — 68 — may obscure an important
point: that strict blood pressure control would probably prevent dementia most effectively if it
starts early and is followed through midlife.
That’s so because hypertension causes harm to blood vessels cumulatively over many years.
Research suggests that decades before declines in memory and thinking skills are noticeable, high blood pressure may begin to damage the brain’s complex network of tiny blood vessels and set the stage for further damage, Schneider said.
Blood pressure control is important at all ages, he said. But in midlife, stricter control may prevent the onset of blood vessel damage. If it doesn’t begin until a person is already in later age, it may be too late to stop that slide toward end-organ damage and, in the case of the brain, dementia, he said.
Alzheimer's Association
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