The Grapevine

High Blood Pressure In Older Adults Linked To Alzheimer's Disease

For older adults, high blood pressure could lead to changes in the human brain in the form of tangles and infarct lesions that are associated with Alzheimer's disease.

The study titled "Late-life blood pressure association with cerebrovascular and Alzheimer disease pathology" was published in the journal Neurology on July 11.

While hypertension in younger individuals has been linked to strokes, the research team wanted to understand how varying levels of blood pressure (high, low, regular) affected blood vessels in the brain in later life.

"What we wanted to do is look at the actual brain tissue to see whether we saw the underlying changes in the brain that cause stroke or the underlying changes in the brain that cause dementia," explained lead author Dr. Zoe Arvanitakis, a professor of neurology at Rush University Medical Center in Chicago.

Apart from changes like plaques and tangles in the brain, she and her colleagues also examined brain lesions known as infarcts. Arvanitakis described them as "areas of dead tissue caused by a blockage of the blood supply," which often go undetected. Infarcts increase with age and have been could potentially lead to a stroke.

Participants included nearly 1,300 people who were all aged 65 years or older. They were all followed until their deaths, which occurred at an average age of 89. About two-thirds of the participants had a history of high blood pressure and 87 percent were taking drugs to manage their hypertension.

Blood pressure is measured in two parts — systolic and diastolic. For example, a blood pressure of 130/80 mmHg indicates a systolic blood pressure of 130 mmHg and a diastolic blood pressure of 80 mmHg.

After examining the autopsy results, the risk of brain infarct lesions was found to be higher in those who had higher average systolic blood pressure readings over the study period. For example, someone who measured 147 mmHg had a 46 percent increased risk of brain lesions compared to someone who measured 134 mmHg.

The main limitation was that researchers failed to find a link between blood pressure and amyloid plaques. These plaques can damage connections between nerve cells and are considered one of the hallmarks of Alzheimer's disease.

Despite this, the findings were considered to be significant by Dr. Ajay Misra who hoped they would encourage more discussion about blood pressure management for older adults.

"This acts as a reminder that you cannot just go and publish that one set of blood pressure guidelines is good for all," said Misra who is the chairman of neurosciences at NYU Winthrop Hospital, New York. "I think it will either be age-specific about how blood pressure should be maintained, or there should be some disease- or circumstance-specific guidelines."