Researchers say controlling blood pressure variability may preserve cognitive function.
Blood pressure is the strength with which blood pushes against the walls of the arteries.
There are two measurements that indicate a person's blood pressure: systolic and diastolic blood pressure. These are measured in millimeters of mercury (mm Hg).
Systolic blood pressure represents the pressure caused by the heart pumping out blood, while diastolic blood pressure represents the pressure caused by the heart filling with blood.
A systolic blood pressure of less than 120 and a diastolic blood pressure of 80 is classed as normal, and this is written as 120/80 mm Hg.
But increasingly, studies have shown that fluctuations in blood pressure over time may also pose health risks, with one study published last year suggesting that blood pressure variability may raise the risk of cardiovascular disease and death.
Now, new research - led by Bo Qin, Ph.D., of Rutgers Cancer Institute in New Brunswick, NJ - suggests that for older adults, fluctuations in blood pressure may speed up decline in cognitive function.
Verbal memory reduced with greater systolic blood pressure variability
To reach their results, the team analyzed data of 976 Chinese adults aged 55 and older who were part of the China Health and Nutrition Survey.
The blood pressure variability of the participants was assessed over 5 years, determined through blood pressure measurements taken at three or four doctor's visits.
Additionally, each participant underwent a number of tests for cognitive function over the 5-year period. These included word recall and counting backward.
The researchers found that subjects who had greater variability in systolic blood pressure over 5 years experienced a faster decline in cognitive function, including a decline in verbal memory - the ability to remember words and other factors relating to language.
Greater fluctuations in diastolic blood pressure were associated with faster decline in cognitive function among adults aged 55-64, but no such link was identified for adults aged 65 and older.
Average systolic and diastolic blood pressure readings - which healthcare professionals tend to focus on - over the 5-year period were not linked to changes in brain function, the authors note.
Controlling blood pressure fluctuations may preserve cognitive function
While the researchers say their study does not prove a causal association between blood pressure variability and faster cognitive decline, they say it adds to increasing evidence that such variability poses health risks.
Based on their results, the researchers say doctors should think about closer monitoring of patients' blood pressure variability.
"Blood pressure variability might signal blood flow instability, which could lead to the damage of the finer vessels of the body with changes in brain structure and function. These blood pressure fluctuations may indicate pathological processes such as inflammation and impaired function in the blood vessels themselves.
Controlling blood pressure instability could possibly be a potential strategy in preserving cognitive function among older adults."
Bo Qin, Ph.D.
In order to confirm their findings, the researchers say longer-term studies and clinical intervention trials are required.