Aggressive treatment of high blood pressure may have another benefit beyond reducing rates of cardiovascular disease in people with hypertension—it could also reduce the risk of memory impairment, a study found. The study showed that using common medications to reduce systolic blood pressure to below 120 reduced the risk of mild cognitive impairment by about 19% compared with lowering to less than 140—the standard target until a few years ago. Mild cognitive impairment is a slight but noticeable decline in memory and other thinking skills and is considered a potential precursor to dementia. It increases a patient’s risk of Alzheimer’s disease, the dementia-causing disorder that affects about 5.7 million Americans.
The new findings came from a study of more than 9,300 patients with high blood pressure that started in 2010 and was funded by the National Institutes of Health. Its main purpose was to test whether more aggressive treatment of blood pressure could improve heart health. In 2015, the NIH stopped the trial early and shared results showing that the more intensive treatment reduced the risk of heart attack and stroke by almost a third and death by nearly a quarter when compared with the standard treatment at the time. After that study was halted, researchers continued to analyse the effect of the more aggressive treatment of dementia and mild cognitive impairment. The new analysis shows that for those with hypertension, “there is something people can do to lower their risk for developing significant memory impairment,” said Jeff Williamson, lead researcher for the study and professor of geriatric medicine at Wake Forest University School of Medicine in Winston-Salem, N.C. Researchers released the results on Wednesday at the Alzheimer’s Association International Conference in Chicago.
Systolic pressure is the top number in a blood pressure reading and is the pressure exerted on arteries when the heart contracts and sends blood to the rest of the body. The lower, or diastolic, the figure is the pressure in the arteries as the heart fills with blood between beats. Optimal blood pressure is considered to be below 120/80. Patients in the more aggressive treatment group took an average of 2.8 medications daily, versus about 1.8 in the less intensive group, Dr Williamson said. Drugs included diuretics and beta blockers and most were available in generic versions, he said. Researchers assessed participants by using memory tests, such as reading people a list of words and then asking them to recall as many words as they could remember. The rates of mild cognitive impairment in both treatment groups were relatively low. Researchers found that 285 participants receiving intensive blood-pressure treatment, or 6.1% of the group, developed mild cognitive impairment, versus 348, or 7.4%, in the standard treatment group.
Still, “on a population level, treating high blood pressure more seriously will have an impact on reducing new cases” of mild cognitive impairment, David Knopman, a clinical neurologist at the Mayo Clinic in Rochester, Minn., said in an interview. He wasn’t involved in the study. Dr Knopman said it’s possible that the aggressive treatment of high blood pressure helps memory by reducing the incidence of undetected mini-strokes in the brain. Patients in the intensive treatment had a higher rate of certain side effects such as hypotension—or abnormally low blood pressure—and electrolyte abnormalities. Patients receiving the more intensive blood-pressure treatment also had a lower rate of dementia, but the difference wasn’t statistically significant, meaning it could have been due to chance. The combined rate of mild cognitive impairment and dementia, however, was statistically significantly lower in the more intensive treatment group. Dr Williamson said it is possible that the treatment duration wasn’t long enough to cut the risk of dementia.
Credit: Peter Loftus for The Wall Street Journal, 25 July 2018.