High Blood Pressure May Be Harming Your Brain While You Sleep

In healthy people, it's normal for blood pressure to drop during the night.  But in hypertensive patients, nighttime blood pressure sometimes doesn't drop, or even increases.  A new study published online in the journal Neurology, shows that those individuals may be more likely to have small areas in the brain that appear damaged from vascular disease and associated memory problems. 

435 people with an average age of 59 had their blood pressure monitored for 24 hours at home with a device that took their pressure every 15 minutes during the day and every 30 minutes at night. Subjects also received brain scans to look for small areas in the brain that appear damaged from vascular disease (called white matter hyperintensities) and took a memory assessment test. 

Fifty nine percent of subjects had high blood pressure (defined as a 24-hour average of more than 130/80 mmHg) or were taking medication for high blood pressure. In half of subjects blood pressure dipped at night, in 40% it remained the same, and in 10% it increased.

After adjusting for age, the results showed that people with high blood pressure that increased overnight had over twice the amount of white matter hyperintensities (an average of over six cubic centimeters of these white matter changes in the periventricular area of the brain)  as the other participants (2.5 cubic centimeters or less).  They also had lower scores on a memory test than the other participants.

Although authors point out that their study only demonstrates association--not causation-- between nighttime hypertension and memory problems, it still provides useful information about how hypertension may be affecting the brain.

“These results add to the mounting evidence that shows the importance of vascular risk factors in contributing to memory problems,” said study author Adam M. Brickman, Ph.D., of Columbia University in New York, N.Y. “They also point to the potential impact of preventing high blood pressure through efforts such as maintaining a healthy weight, being physically active and having a healthy diet.”

“Longer studies that follow people over time will be needed to determine whether these factors do indeed lead to white matter changes and memory problems, although our initial findings are indeed consistent with this hypothesis,” Brickman said.

The research study, "White matter hyperintensities mediate the association of nocturnal blood pressure with cognition," was published April 15, 2020 online in Neurology.   https://doi.org/10.1212/WNL.0000000000009316