High blood pressure has long been regarded as a health concern. Now swings in blood pressure are getting attention from health researchers, too.
A new study published Monday in the American Heart Association journal Hypertension points out that older people whose blood pressure fluctuated over time were at greater risk of suffering from loss of brain function.
The study was observational, so it could not establish an exact cause-effect relationship between the two phenomena. But the connection between the two is plausible, according to comments the study's lead author, Bo Qin, made in a press release.
"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," said Qin, a researcher at Rutgers Cancer Institute in New Brunswick, New Jersey.
Blood pressure fluctuates even in healthy people. For example, it tends to be lower in the morning and rise throughout the day. But previous research has correlated especially wide swings over time with heart problems, including heart attack, stroke and even death.
Qin and her colleagues looked at health data from 1,000 Chinese adults, surveyed in a large health study called the China Health and Nutrition Survey.
The survey contained information from blood pressure readings as well as from mental quizzes that tested things such as word recall and the ability to count backwards.
Some survey participants had blood pressure readings that changed considerably between visits to the doctor. Those people tended to perform worse on the cognitive tests.
The variability was the key, rather than the blood pressure levels themselves: The researchers did not find that participants' average blood pressure readings correlated with worse cognitive performance.
That matters because doctors tend to focus more on average blood pressure readings when examining patients.