Everyone knows stress can cause headaches and sleepless nights. But a new study suggests it can actually shrink your brain.

We’re not talking run-of-the-mill stressors here, like a looming deadline or a missed bus.

“These are bad things happening, like a relationship breakup, loss of a loved one, being held at gunpoint,” says Yale neurobiologist Rajita Sinha, senior author of the new report.

Simply feeling stressed-out was not linked to gray matter shrinkage. But feeling stressed-out combined with a history of stressful life events was.  In particular, stress was linked to markedly less gray matter than expected in a part of the prefrontal cortex that regulates emotion and self-control, not to mention blood pressure and blood sugar.

That shrinkage might serve as a red flag about a greater risk of chronic diseases such as high blood pressure as well as psychiatric disorders, according to the researchers. And maybe it’s already affecting brain function in the healthy individuals she studied, Sinha says.

In other words, the stresses of modern life are far more complicated than what our ancestors experienced. “You can say stresses are a part of life, so what’s the big deal?” Sinha says. But it is a big deal, she adds, because there’s extensive evidence that stress has contributed to the rise in chronic diseases.

Most human research about the impact of stress on brain structure has focused on patients with stress-related psychiatric disorders such as addiction and anxiety, according to the authors. Those studies have found decreased volume in the frontal lobe, considered the center of emotion control and personality.

But studies of the cumulative effects of stress on the brains of healthy people are rare, Sinha’s team writes in a paper published online this week in Biological Psychiatry.

The study enrolled 103 health adults ages 18 to 48. Researchers conducted structured interviews with the volunteers to collect information about stressful life events and subjective feelings of chronic stress.

The scientists then used MRI to scan the volunteers’ brains.

Whose brains shrunk more, men’s or women’s? You might think you know the answer, but the researchers don’t, because they didn’t have enough women to compare the sexes.

The take-home message, Sinha says, is that the better you cope with stress -- take a walk, call a friend -- the better off your brain will be.

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