Scientists have made a startling claim that could reshape our understanding of a common medical condition: a little-known part of the brain may be the hidden driver behind high blood pressure. The discovery points to the lateral parafacial region, a bundle of nerves in the brainstem, as a potential culprit for hypertension.
The Brain's Hidden Control Centre
Located in the brainstem, the lateral parafacial region is responsible for controlling automatic bodily functions like digestion, breathing, and heart rate. It also springs into action during activities like laughing, exercising, or coughing, triggering the forced exhalations needed for these actions. However, researchers from the University of Auckland in New Zealand have now found a more concerning role.
Their laboratory work indicates that activating this specific brain region can also stimulate nerves that cause blood vessels to tighten. This constriction raises blood pressure, potentially leading to the chronic condition of hypertension. In experiments conducted on rats, the team activated and inhibited the nerves in this area while monitoring blood pressure. They observed a direct correlation: blood pressure increased when the lateral parafacial region was active and decreased when it was suppressed.
A Potential New Target for Treatment
Dr Julian Paton, the physiologist who led the research, stated emphatically: 'We've unearthed a new region of the brain that is causing high blood pressure. Yes, the brain is to blame for hypertension!' He explained that in hypertensive conditions, this region becomes activated, and when the team inactivated it, blood pressure returned to normal levels.
The study, published in the journal Circulation Research, used viruses to either excite or calm the nerves in the lateral parafacial region. Scientists tracked signals from another part of the brainstem, the rostral ventrolateral medulla, which controls blood pressure. The results showed that exciting the parafacial region triggered active expiration and activated nerves that raise blood pressure by tightening vessels. These nerves are part of the sympathetic nervous system, which governs the body's involuntary 'fight-or-flight' response.
Conversely, inhibiting these nerves stopped active expiration and relaxed blood vessel walls, allowing blood pressure to normalise while breathing continued unaffected. This finding suggests a promising new avenue for developing treatments focused on calming these overactive brain nerves.
Hypertension: A Widespread Health Crisis
Hypertension is the most common medical condition in the United States, affecting an estimated 120 million adults, or nearly half the population, according to the CDC. In the UK, it is similarly prevalent, impacting millions and significantly increasing the risk of stroke, heart attack, and dementia. Doctors define normal blood pressure as less than 120/80 mmHg, with readings above this threshold considered high.
While lifestyle factors like a high-salt diet, stress, obesity, and alcohol consumption are well-known contributors, this new research adds to a growing body of evidence implicating the brain. The brain sends signals to adjust heart rate and blood vessel size, directly influencing blood pressure. It remains unclear what proportion of hypertension cases might be caused by this newly discovered brain mechanism.
This research builds on previous studies, including work from the MD Anderson Cancer Center in June last year, which linked an overactive hypothalamus—another brain region controlling the sympathetic nervous system—to high blood pressure. That study found that a protein called RCAN1 could block the calming protein calcineurin, leading to overactivity.
As the next step, researchers must find a way to test this mechanism in humans to confirm the findings observed in rats. If validated, it could lead to revolutionary new therapies for a condition that is a leading cause of death and disability on both sides of the Atlantic.
