Knowing you have higher than normal blood pressure — and taking medications daily to treat it — may be one key to avoiding dementia in later life, a new study found.
Scientists already know that having high blood pressure, particularly between ages 40 and 65, increases the risk of developing dementia in later life, said study coauthor Ruth Peters, an associate professor at the University of New South Wales in Australia, via email.
But she added that research has been less clear on whether lowering blood pressure in older adults would reduce that risk.
“What is so exciting about our study is that the data shows that those people who were taking the blood pressure lowering medication had a lower risk of a dementia diagnosis than those taking a matching placebo,” said Peters, who is also a senior research scientist at Neuroscience Research Australia, a nonprofit research organization.
Blood pressure is measured in units of millimeters of mercury (abbreviated as mmHg), which consists of two numbers: an upper or systolic reading that represents the maximum amount of pressure in your arteries, and the lower or diastolic reading that shows the pressure in your arteries when your heart muscle is at rest between beats.
The study, published this week in the European Heart Journal, combined data from five large randomized, double-blinded clinical trials of more than 28,000 older adults with an average age of 69 from 20 countries. All had a history of hypertension.
Each of the clinical trials compared people taking blood pressure medications with people taking a matching placebo pill and followed them for an average of 4.3 years. Pooling the data, Peters and her team found that a drop of about 10 mm/Hg on the systolic and 4 mm/Hg on the diastolic blood pressure readings at 12 months significantly lowered the risk of a dementia diagnosis.
In addition, there was a broad linear relationship: As blood pressure dropped, so did cognitive risk, which held true until at least 100 mm/Hg systolic and 70 mm/Hg diastolic, the study said. There was also no sign that blood pressure medications may harm blood flow into the brain at later ages.
When sex, age or history of stroke were taken into account, there was no difference in the outcome.
“We know that what we do throughout life is likely to have an impact on brain health in late life,” Peters said. “So the best advice we can give is to lead a healthy lifestyle at all ages, and of course, if you are prescribed medication to control your blood pressure to take it according to the instructions from your doctor.”
Lifestyle changes can add to or in some cases replace the need for hypertension medications, according to the American Heart Association. Suggested actions include limiting alcohol, managing stress, stopping smoking, eating a well-balanced and low-salt diet, getting plenty of exercise and sleep, and taking blood pressure medications as directed.
Research shows such changes can work. A 2021 study found that diet, exercise and a lower salt intake also reduced blood pressure in people with resistant hypertension, which is high blood pressure that doesn’t respond to medications.
In one 16-week study published in 2018, people who went on a low-salt diet, exercised and practiced weight management techniques (such as watching portion sizes) lowered their blood pressure by an average 16 mmHg systolic and 10 mmHg diastolic, the American Heart Association said.
The diet used was the DASH diet, which stands for Dietary Approaches to Stop Hypertension. An award-winning eating plan, DASH has a simple premise: Eat more veggies, fruits and low-fat dairy foods; limit foods high in saturated fat; and limit your intake of sodium to 2,300 milligrams a day — that’s about 1 teaspoon of table salt.
The DASH meal plan includes four to six servings of vegetables and another four to six servings of fruit; three servings of whole-grain products; two to four servings of fat-free or low-fat dairy products; and several servings each of lean meats and nuts, seeds and legumes each day.
However, if lifestyle changes don’t significantly lower blood pressure within six months, the American Heart Association recommends adding hypertension prescription medications while continuing the healthy behaviors.