Blood pressure reduction is associated with lowered risk of dementia
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Bringing down high blood pressure reduces the risk of dementia and cognitive impairment, according to a large study of people in China.
Many studies have linked high blood pressure, also known as hypertension, with a greater risk of developing dementia. Some research has also indicated that a side effect of blood pressure treatment may be lower dementia risk.
Now, Jiang He at the University of Texas Southwestern Medical Center in Dallas and his colleagues have directly looked at the effectiveness of medicines that reduce blood pressure on dementia and cognitive impairment.
They studied 33,995 people in rural China who were all 40 or older and had hypertension. The participants were split into one of two random groups, each with an average age of about 63 years old.
The first group received, on average, three anti-hypertensive medication such as ACE inhibitors, diuretics or calcium channel blockers to aggressively ensure their blood pressure stayed down. They also had coaching on home blood-pressure monitoring and on lifestyle changes that could help keep blood pressure down, including weight loss and reducing intake of alcohol and salt.
The other set, treated as the control group, got the same coaching and a more usual level of treatment for the region, involving just one medication on average.
At a follow-up appointment after 48 months, the participants had their blood pressure tested and were measured for signs of cognitive impairment using standard questionnaires.
Concerns about hypertension start when a person’s systolic pressure exceeds 130 millimetres of mercury (mmHg) or diastolic pressure goes over 80 mmHg – that is, blood pressure higher than 130/80.
On average, people who received many medications had dropped their blood pressure from 157.0/87.9 down to 127.6/72.6 mmHg, while the control group managed to take it from 155.4/87.2 down just slightly to 147.7/81.0 mmHg.
The researchers also found that compared with the control group, 15 per cent fewer people on multiple medications received a dementia diagnosis during the study, and 16 per cent fewer had cognitive impairment.
“The findings from this study demonstrated that blood pressure reduction is effective in reducing the risk of dementia in patients with uncontrolled hypertension,” says He. “This proven-effective intervention should be widely adopted and scaled up to reduce the global burden of dementia.”
“For many years, a lot of people have known that blood pressure is a likely risk factor for dementia and this has provided super compelling evidence of the clinical benefit of blood pressure reduction medications,” says Zachary Marcum at the University of Washington in Seattle.
Raj Shah at Rush University in Chicago says that adding to the evidence that treating high blood pressure can help stave off dementia is helpful, but it is just one piece of the dementia puzzle, because multiple factors influence the brain’s abilities as we age.
“We should treat high blood pressure for multiple reasons,” says Shah. “For people’s longevity and well-being and so they can age healthily over time.”
Marcum also says that to avoid dementia, people should think more widely than just about blood pressure. He says there are other known risk factors that are linked to an increased risk of dementia, including smoking, inactivity, obesity, social isolation and hearing loss.
And different factors become more influential at different stages of life. To reduce the risk of dementia, “there’s got to be a holistic approach over the course of a lifetime”, says Shah.
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