Cortisol Controls Stress, but What Else?
Nov. 9, 2015 -- Although cortisol is known as the “stress hormone,” researchers suspect it plays a much larger role in our health.
A recent study, for example, linked cortisol to memory in older adults. People with unusually high nighttime cortisol levels had reduced brain size and did more poorly on cognitive tests. Scientists are also investigating the hormone’s ties to heart disease risk and weight, to name a few.
“The effects of cortisol are felt over virtually the entire body,” says endocrinologist Robert Courgi, MD, who practices at Southside Hospital in Bay Shore, N.Y.
But researchers are just starting to understand what those effects are.
“Many of us endocrinologists are interested in this idea that our day-to-day cortisol levels, whether they are high or low, might make a difference to our overall health,” says Lynnette Nieman, MD, chief of the Endocrinology Consultation Service at the National Institutes of Health Clinical Center. “But there aren’t a lot of data that speak to that question.”
In the brain study, researchers tested morning and evening cortisol levels in the saliva of 4,244 older adults. Those with higher evening levels appeared to have smaller brain volume and worse brain function, like processing speed and “executive functioning” skills, which include paying attention, switching focus, planning, and organization. Those with higher morning cortisol levels, though, appeared to have better brain function.
But the researchers couldn't say which came first: unusually high cortisol or the reduced brain size.
“Clearly there is a physiologic relationship,” says Courgi, who wasn't involved in the research. “But is it cause and effect? Is it because there’s too much cortisol that you’re having memory problems? Or does the loss of memory lead to elevated cortisol?”
Another link researchers are looking into is the hormone’s potential role in the number you see when you step on the scale.
“There’s concern that cortisol causes weight gain, but there’s also the question of cause and effect,” Courgi says. “Is it the weight gain that elevates the cortisol, or the elevated cortisol that leads to weight gain?”