A study of more than 1200 people around the age of 80 has suggested that high blood pressure in later life is associated with Alzheimer鈥檚 disease.
Researchers tracked volunteers鈥� blood pressure for an average of eight years before their death, before performing autopsies to look for signs of Alzheimer鈥檚 disease in the brain. These included plaques of sticky amyloid protein between brain cells, and tangles of tau proteins inside them.
The scientists observed that participants with a higher average systolic blood pressure 鈥� the pressure in the arteries when the heart beats 鈥� during these years had a larger number of tangles, but not plaques, in the brain.
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Long-running debate
There is a longstanding debate about the relationship between blood pressure and Alzheimer鈥檚 disease 鈥� high blood pressure in middle age is thought to be one of many possible risk factors for the condition, but the evidence is not clear-cut.
The team behind the new study say that theirs is the first to show a link between Alzheimer鈥檚 and blood pressure in older people. But researchers do not know yet how one might affect the other.
One theory is that blood pressure changes could lead to impaired delivery of nutrients and clearance of toxic waste products from the brain, says Daniel Nation at the University of Southern California. 鈥淎nother possibility is that these changes in arterial pulsation and perfusion may cause a mechanical injury to the blood鈥揵rain barrier, causing toxic blood products to enter the brain and exacerbate neurodegeneration,鈥� says Nation.
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