- High blood pressure (hypertension) in older people may increase the risk of brain disease, especially brain lesions
- Blood pressure in later life may be linked to Alzheimer's disease, and brain lesions called infarcts
Older people with higher blood pressure may have more signs of brain disease, especially brain lesions, reports a new study. The findings of the study are published in the journal Neurology®.
A team of researchers observed a link between higher blood pressure and more markers of Alzheimer's disease, tangles in the brain.
An individual's blood pressure changes with aging and disease, therefore it is important to find out the kind of impact it may have on the brain, said study author Zoe Arvanitakis, MD, MS, of the Rush Alzheimer's Disease Center at Rush University Medical Center in Chicago, and a Fellow of the American Academy of Neurology.
"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."
What is Hypertension?
Blood pressure is measured in terms of systolic pressure and diastolic pressure. The upper value is called systolic blood pressure, i.e., the pressure in the blood vessels when the heart beats. The lower value is called diastolic blood pressure, i.e., the pressure when the heart is at rest.
The average blood pressure of a person is less than 120/80 millimeters of mercury (mmHg). The blood pressure level of a person with hypertension is above 140/90 mm Hg.
Details of the Study
The study participants were 1,288 older people who were followed until their deaths which was an average of eight years later. The average age at death was 89 years.
The average systolic blood pressure for those registered in the study was 134 mmHg, and the average diastolic blood pressure was 71 mmHg.
The study shows
- Around two-thirds of the participants had a history of high blood pressure
- About 87 percent were taking high blood pressure medication
- Nearly a total of 48 percent of the participants had one or more brain infarct lesions.
The blood pressure level of the participants were recorded every year, and autopsies were conducted on their brains after death.
Findings of the Study
The research team found that the risk of brain lesions was higher in people with higher average systolic blood pressure over the years.
For an individual with one standard deviation above the average systolic blood pressure, there was a 46 percent increased chance of having one or more brain lesions.
Similarly, with one standard deviation above the average systolic blood pressure, a 46 percent increased risk of large lesions and 36 percent increased risk of smaller lesions.
Arvanitakis observed that an important additional result of the study was that people with a declining systolic blood pressure also had a greater risk of one or more brain lesions, so it was not just the level but also the declining blood pressure that was associated with brain lesions.
On a slightly different note, the research team found that having a diastolic blood pressure that declined over time was also associated with an increased risk of lesions.
Those who had an increase of one standard deviation from an average diastolic blood pressure had a 28 percent higher risk of one or more brain lesions.
The results did not change when the research team controlled for other factors such as whether the participants used high blood pressure drugs that could affect the risk of brain lesions.
When observing for signs of Alzheimer's disease in the brain at autopsy, the research team found a link between higher average late-life systolic blood pressure over the years before death and a higher number of tangles (twisted fibers within neurons), but not plaques (protein buildup between nerve cells). Arvanitakis said this link is difficult to understand and will need further research.
"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.
Limitations of the Study
The main limitations of the study include that the research team only had access to blood pressure readings during the participants' later life and not middle age. Furthermore, the blood pressure readings were recorded only once a year and not more frequently.