Chronic stress may be able to rewire our brains, keeping our blood pressure high all the time, even after we relax, emerging research suggests.
When we get stressed – it could be tight deadline; a fight with our partner – our fight-or-flight mechanism kicks in, and our brain pushes our blood pressure up, giving us a short burst of energy and mental sharpness.
But if that stress is prolonged for a few months, researchers now believe our brain might ‘lock in’ that pressure increase. And elevated blood pressure is very bad for our internal organs.
“We know that people who have work-related or emotional stress, they get high blood pressure,” says Professor Vaughan Macefield, the newly appointed head of human autonomic neurophysiology at the Baker Heart and Diabetes Institute in Melbourne.
“If you’re constantly being bullied, or your boss is putting you down, then these things stick. At night you may not sleep well, and that in itself can lead to cardiovascular problems.”
The theory is emerging as scientists start to look at one of the biggest determinants of heart health: the brain.
“Given that many forms of cardiovascular disease – like high blood pressure – are brought about by changes in brain activity in the first place, it is kind of surprising we don’t think about the brain more,” says Professor Macefield.
The way the brain regulates blood pressure is remarkable. Each blood vessel in your body is surrounded by small muscles. Squeezing those muscles ramps up your blood pressure.
When we stand up, for example, the blood vessels in our legs squeeze to push blood up into the brain. That sensation of your whole body squeezing itself when you’re working hard at the gym? That’s the brain shunting blood into your muscles.
But when the brain is operating under pressure, that system can go haywire.
Professor Macefield comes to the Baker from Western Sydney University, where his key work was on pain and stress.
Volunteers in one of his trials were hooked up to syringes that slowly injected water into their muscles to stimulate their pain and stress responses, while researchers watched their brains on functional MRI [fMRI] machines.
“It’s bloody painful – like you’ve been kicked in the shins,” he says. “People can tolerate that for an hour.
“The brain reacts within a minute, starting to drive up blood pressure – but only in some people, not others. And we see changes in the brain’s wiring occurring at the same time.
After the pain ended, the volunteers’ blood pressure dropped back to normal levels. But, watching their brains using an fMRI machine, Professor Macefield discovered everything was not quite so simple.
Even the short burst of pain led to structural changes within their brain. If that pain was chronic, Professor Macefield believes that the brain might end up so significantly rewired that blood pressure would be “jammed” at a high level.
It has not been proven yet, but Professor Macefield believes people under chronic stress – stress that continues for three months or longer – are likely to respond in the same way.
Your blood pressure only needs to remain high for a few months to do serious damage to your internal organs, Professor Macefield says, and is a major risk factor for developing potentially-fatal heart disease.
Luckily, his work suggests its own solutions. If high blood pressure is at least partially a problem of the brain, it opens up the possibility of using psychology rather than surgery to treat cardiovascular problems.
“We’re trying to find areas in the brain that we can target perhaps through psychological interventions to help alleviate the stress and therefore lower blood pressure,” he says.
“We know when we have deep, relaxing sleep, our blood pressure goes down – and so does the activity in these nerves that control blood pressure.
“We’re now trying to find out where in the brain this occurs, such that reducing this activity in the awake state may lead to a lowering of blood pressure.”
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Source: The Sydney Morning Herald