Study unlocks dementia trigger

A study to determine the effects of low blood pressure on heart health has yielded a startling result for dementia research, with scientists describing the finding as “potentially groundbreaking”.

Participants with heart problems who were treated with drugs to return their blood pressure to the ideal range were found to be 15 per cent less likely to develop mild cognitive impairment (MCI), which is regarded as a ‘gateway’ to dementia, according to a report in Time magazine

The SPRINT Memory and Cognition in Decreased Hypertension (SPRINT-MIND) study involved more than 9300 people with an average age of 68 who had heart disease or were at greater risk of developing heart disease. Their blood pressure was lowered to either less than 120mmHg systolic, which is considered ideal, or 140mmHg systolic, which is categorised as high. (Current guidelines, revised after the study began, recommend that the upper number be kept under 130mmHg.)

People who lowered their blood pressure to under 120mmHg lowered their risk of both mild cognitive impairment – the gateway to dementia – or probable dementia by 15 per cent, compared to people who lowered their blood pressure to 140mmHg, according to the report.

“Controlling blood pressure is not only good for the heart but good for the brain,” says Dr Jeff Williamson, chief of geriatric medicine at Wake Forest School of Medicine in North Carolina, and one of the lead investigators in the trial.

“This is the first intervention of any kind that has been proven in a randomised controlled trial to reduce the risk of mild cognitive impairment.”

In previous studies, it was found that people with high blood pressure were more likely to develop dementia, however the reverse had not been tested.

Participants in the study were treated for only three years by which time it was obvious that lower blood pressure protected against heart disease.

However, study authors say it is the first time scientists have found something that can lower MCI risk in a rigorous, randomised controlled trial.

“This provides great encouragement for people to say, ‘Yes, make sure your blood pressure is well controlled’, because right now it’s one of the things you can do to prevent mild cognitive impairment,” said Dr Williamson. “And this opens the door to testing more interventions.”

Dr Williamson said that recent trials of new drugs that doctors had hoped could slow or even reverse the disease had been disappointing and that the blood pressure finding was “potentially groundbreaking”.

Explaining further, he said: “I like to illustrate the idea to my patients with the analogy of air pressure in our tyres. You don’t want to have too low or too high pressure or you will damage the tyres. The same goes for blood pressure. Over time, high blood pressure can damage the walls of very fragile arteries that deliver blood to the brain and other organs. And that can produce some of the things we see associated with dementia – inflammation and small strokes.”

Alzheimer’s Association chief science officer Maria Carillo described the finding as “a very big deal”. “Now we have evidence that lowering blood pressure is linked to brain health as well. Before, it was strongly suggested, but now we know from a study that it can make a difference.”

A study published earlier in Neurology supports the SPRINT-MIND finding. In that study, researchers at the Rush Alzheimer’s Disease Center in Chicago found that people with higher blood pressure tended to have more brain lesions, or areas of dead brain tissue, as well as tangles of tau protein, a hallmark of Alzheimer’s.

Are you hopeful that the volume of research worldwide is making progress? Do you know whether your blood pressure is in the healthy range?

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Written by Janelle Ward

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