Normal Average Blood Pressure Can Hide Dangerous Swings

Researchers at the University of Virginia School of Medicine in the United States have identified a small group of nerve cells in the brainstem that helps keep blood pressure steady through the day. The finding suggests that blood pressure problems may depend not only on average readings but also on how much pressure fluctuates. The study was published in the scientific journal Circulation Research.

Fluctuations as a separate risk

Blood pressure is usually judged by its average values, but a growing body of evidence indicates that changes through the day matter as well. Rapid or excessive swings can independently raise the risk of heart disease, stroke and brain injury, even when average readings are within the normal range.

The brainstem controls essential involuntary functions. The newly studied cells appear to limit rises and drops in pressure as people move between everyday activities such as sleeping, waking, standing and exercising.

What the team found

"What we found is that a loss of just a few hundred nerve cells leads to unstable blood pressure even though the mean blood pressure was normal," said lead investigator Stephen Abbott. In his words, this shows the system that keeps pressure steady from moment to moment is no longer working.

The same cells have previously been found damaged or missing in people with multiple system atrophy, a rare, fatal neurological disorder related to Parkinson's disease, which is often accompanied by severe blood pressure regulation problems. The new results raise the possibility that disruption of these cells may also contribute to unstable pressure in other medical conditions.

Abbott stressed that the issue is not just lowering the numbers but keeping blood pressure stable. Understanding the mechanism could eventually help researchers develop treatments that reduce harmful fluctuations.

The work was funded by the US National Institutes of Health. It also reflects the goals of the university's newly established Paul and Diane Manning Institute of Biotechnology, which aims to advance research into complex diseases and help laboratory findings reach patients more quickly.