Scientists discover surprising cause of high blood pressure

A little-known part of the brain may be driving your high blood pressure, scientists have claimed.

The lateral parafacial region is a bundle of nerves in the brainstem that controls automatic functions such as digestion, breathing and heart rate.

It also activates when someone laughs, exercises or coughs, triggering the forced exhalations that create these sounds.

But now, researchers in New Zealand say they have found that activating the region can also trigger nerves that cause blood vessels to tighten, which can raise blood pressure, causing the chronic medical condition hypertension.

In a lab, researchers activated and inhibited the nerves in the region while tracking blood pressure, finding that blood pressure rose when the lateral parafacial region was active and fell when it was inhibited.

Dr Julian Paton, a physiologist at the University of Auckland who led the research, said in a statement: ‘We’ve unearthed a new region of the brain that is causing high blood pressure. Yes, the brain is to blame for hypertension!

‘We discovered that, in conditions of high blood pressure, the lateral parafacial region is activated and, when our team inactivated this region, blood pressure fell to normal levels.’

The study was carried out in rats and researchers will need to find a way to test the region in humans in order to confirm their findings.

It was not clear what proportion of high blood pressure cases may be caused by this mechanism. Previous research suggests that lifestyle factors such as a high-salt diet, stress, obesity and alcohol consumption are all key drivers of high blood pressure.

But a growing body of research suggests the condition may have a link to the brain, which sends signals to the rest of the body to adjust heart rate and blood vessel size – and thus, blood pressure.

Researchers said that their findings could be used to help develop new treatments for high blood pressure that focus on calming nerves in the brain that may cause the condition. 

Hypertension is the most common medical condition in the US. An estimated 120million adults, or nearly half the population, suffer from the condition, according to the CDC.

Normal blood pressure is considered to be less than 120 / 80 mmHg. The first number measures the pressure of blood on artery walls when the heart beats, while the second number measures the pressure of blood on artery walls in between beats. 

High blood pressure is considered to be a reading above 120 / 80 mmHg.

Doctors urge people to reduce their blood pressure, warning it can damage blood vessels and raise their risk of stroke, heart attack, dementia and a range of other conditions. About one in six deaths in the US are linked to the condition.

The CDC warns the condition is linked to 664,470 deaths every year, or about one in five fatalities recorded annually nationwide.

Blood pressure is generally treated via medications that can relax blood vessels.

Patients are also recommended to maintain a healthy weight, exercise regularly and eat a healthy diet to help reduce their blood pressure. 

In the study, published in the journal Circulation Research, the researchers used viruses to excite or calm the nerves in the lateral parafacial region.

Scientists tracked signals from the rodents’ rostral ventrolateral medulla, a part of the brainstem that controls blood pressure, and monitored their blood pressure.

Results showed that exciting the parafacial region in rats triggered the active expiration of air and activated the nerves that raise blood pressure by tightening blood vessels.

These blood pressure-raising nerves are part of the sympathetic nervous system, or involuntary nervous system. This system is also responsible for the body’s ‘fight-or-flight’ response.

Researchers found that inhibiting the nerves stopped active expiration and loosened the walls of blood vessels, allowing blood pressure to return to normal. Breathing went on as normal.

Previous research published in June last year by MD Anderson Cancer Center suggested that the hypothalamus, a region of the brain that controls the sympathetic nervous system, could be linked to high blood pressure.

Researchers found that when this area was overactive, it led to high blood pressure, raising the risk of heart disease and dementia. 

In a lab model, they found that normally a protein called calcineurin is released in the hypothalamus and calms brain signals.

But they also found that this protein could be blocked by another protein, called RCAN1, which triggers the hypothalamus to become over-active and stops it from working normally.