“Blood pressure changes with aging and disease, so we wanted to see what kind of impact it may have on the brain,” said study author Zoe Arvanitakis of the Rush Alzheimer’s Disease Center at Rush University Medical Center. “We researched whether blood pressure in later life was associated with signs of brain aging that include plaques and tangles linked to Alzheimer’s disease, and brain lesions called infarcts, areas of dead tissue caused by a blockage of the blood supply, which can increase with age, often go undetected and can lead to stroke.”
The researchers followed 1,288 older people from around the age of 80 until they passed away. The average follow-up period was eight years’ time and the average age of death was 89. Blood pressure was measured each year of the experiment and the participants gave consent to autopsies at the time of death. Around two thirds of the participants had a history of high blood pressure and 87 percent were being treated with high blood pressure medication. Unfortunately, the researchers did not have information on blood pressure from early in life, only during the elderly portion of the participants’ lives.
High Blood Pressure Related to Brain Lesions
At the end of the experiment, the researchers found that the participants with a higher average systolic blood pressure over the years were more likely to have brain lesions. Systolic blood pressure is the top number on a blood pressure measurement, indicating the pressure in the blood stream when the heart beats. The analysis showed that the higher an individual’s blood pressure was on average, there was a correlational increase in the likelihood that they also had brain lesions.
The results also showed that diastolic blood pressure was related to brain lesions, but to a smaller degree. One standard deviation above the average systolic blood pressure was related to a 46 percent higher chance of having brain lesions, whereas one standard deviation above the average diastolic blood pressure was related to only a 28 percent higher chance of having brain lesions. Diastolic blood pressure is the second number on a blood pressure measurement, representing the pressure in the bloodstream between heartbeats.
Even when the researchers adjusted the data for other factors which may have influenced the development of brain lesions, the results remained consistent that high blood pressure increased the risk of brain disease. In terms of Alzheimer’s, the data showed that higher blood pressure across the years leading up to death was related to increased tangles, but not plaques, both of which are associated with the development of Alzheimer’s.
“While our findings may eventually have important public health implications for blood pressure recommendations for older people, further studies will be needed to confirm and expand on our findings before any such recommendations can be made,” said Arvanitakis.
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