Keeping your blood pressure down could significantly lower your risk of dementia and cognitive impairment, a major new study has found.
Scientists have long known that there is a link between high blood pressure and cognitive problems among older adults. But the new study is one of the first big trials to prove that medicines to lower blood pressure can alleviate the risk of dementia, which affects an estimated 57 million people worldwide.
The late-stage clinical trial involved almost 34,000 people with high blood pressure in rural China who were split into two groups. On average, they were about 63 years old and had been dealing with high blood pressure for eight years.
Community health workers gave half of the participants cheap, readily available medication to treat high blood pressure, told them how to monitor their levels at home, and counselled them on lifestyle changes such as salt and alcohol intake, and weight loss.
The other group received standard care – they were told to manage their blood pressure. These patients are typically advised to eat healthily and limit their salt consumption.
Over the next four years, the group that received medication and counselling had better blood pressure control, which reduced the risk of dementia by 15 per cent and the risk of cognitive impairment by 16 per cent, according to the study, which was published in the journal Nature Medicine.
The findings suggest that concentrated efforts to keep people’s blood pressure in a healthy range could help curb the burden of dementia, the researchers said.
“This is a landmark study with a very large sample size and a robust effect,” said Masud Husain, a professor of neurology at the University of Oxford, who was not involved with the research.
“It’s a wake-up call to treat high blood pressure intensively, not just to protect the heart but also the brain,” Husain said in a statement.
The results are in line with another big clinical trial in the United States, which found that intensive blood pressure treatment led to a lower risk of cognitive impairment, including issues that may be linked to dementia.
Other studies also indicate that lifestyle decisions could affect whether someone develops dementia. Last year, researchers said that addressing 14 risk factors – including high blood pressure, smoking, and physical inactivity – could delay or prevent half of all dementia cases.
But most research thus far has identified associations between dementia and lifestyle factors, making the new study – which offers some of the first causal evidence – more important.
The findings could change the way health workers think about dementia prevention, given that there is no cure for the condition and its toll is expected to nearly triple by 2050.
Independent experts said more research is needed to understand how other factors, such as genetics, interact with high blood pressure to raise dementia risks. They also want to know if the results will hold up in other groups of people and for longer periods of time.
Treating high blood pressure is also not guaranteed to protect against dementia. About 670 people in the study who received the extra medical care – 4.59 per cent – still developed the condition.
The study has some other limitations. While it did not include people who were already diagnosed with dementia, the researchers did not test people’s cognitive function before the experiment began.
Even so, independent experts said the findings make the case for prioritising blood pressure control as people age, which they said could be especially helpful in areas with less access to advanced medical care.
“We have an intervention that moves the needle on dementia risk, that can be delivered to large numbers of people in their communities, at modest cost,” said Atticus Hainsworth, a professor of cerebrovascular disease at St George’s, University of London who was not involved with the study.
Given the results of the Chinese study were similar to the US trial, “these concordant findings may prompt changes in healthcare policy guidelines,” he added.
