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High blood pressure could be linked to Alzheimer’s disease
A new study looking at brain tissue is another piece of the puzzle about how high blood pressure might affect the brain
The link between blood pressure and heart disease and stroke is well established. But the link with brain function is a growing area of research.
Studies have shown that high blood pressure can play a role in vascular dementia – where a series of mini strokes or damage to the blood vessels cuts off some of the blood supply to the brain. Now, a new study published in the journal Neurology has shown a possible link between blood pressure and Alzheimer’s disease - the most common type of dementia.
What did the study involve?
Scientists based in Chicago measured the blood pressure of 1,288 people aged 59 – 102 every year. After the people taking part had passed away years later, at an average age of 89, the scientists examined their brain tissue to look for signs of Alzheimer’s.
They found that those with higher blood pressure tended to have more signs of Alzheimer’s disease. They were more likely to have lesions, also known as infarcts – areas of tissue which have died due to lack of blood supply – and tangles of dying nerves called tau. But high blood pressure was not linked to plaques, a characteristic of Alzheimer’s which can damage the connections between nerve cells.
A systolic blood pressure (the top number) of 147mmHg was linked to a 46% higher chance of having one or more infarcts in the brain compared to someone with a systolic reading of 134mmHg.
The average blood pressure in the trial was 134/71mmHg and most people were taking blood pressure medicines. High blood pressure is usually diagnosed at 140mmHg, and the ideal is under 120mmHg, so the people in this study did not have excessively high blood pressure.
Previous studies have shown a possible link with dementia and Alzheimer’s, but this is the first one that explores how blood pressure affects tissues in the brain.
What do the results mean?
The authors commented that it’s plausible that altered blood pressure in later life could cause infarcts in the brain, especially given the amount of evidence linking high blood pressure to stroke. But that the study could not prove that high blood pressure causes infarcts or Alzheimer’s. The team are planning further research to find out more, for example, whether those who lowered their blood pressure during the trial had a lower risk of damage to the brain.
Nirmala Markandu, Hypertension Nurse Specialist at Blood Pressure UK, said: “The study found that raised blood pressure was linked to more brain infarcts, but this did not mean those people were suffering with the symptoms of Alzheimer’s, so this is not a cause for alarm. It is however another piece of the puzzle about how high blood pressure might affect the brain.”
Meanwhile, a new study finds the age of 50 could be key to lowering dementia risk
Another study looking into blood pressure and dementia this year found that the age of 50 could be a key time for managing blood pressure. London researchers looked at nearly 9,000 people in their 50s, 60s and 70s in a trial that begin in 1985. They found that those who had systolic blood pressure over 130mmHg in their 50s, but not in their 60s and 70s, had a higher risk of dementia later on, for example in their mid 70s. They also found that having high blood pressure for a longer time was linked to a higher risk of dementia
The research known as the Whitehall II cohort study was published in the European Heart Journal this September. It adds more detail to previous studies which have shown that high blood pressure in midlife is linked to dementia later on. The authors commented that it could have implications for policy guidelines, which at the moment only use the more generic term ‘midlife’ and are focused on blood pressure over 140mmHg, rather than 130mmHg.