Study Explains How Stress Makes People Sick

It's common wisdom that stress can make people sick. Now, a team of scientists from UCLA have figured out exactly how that happens. UCLA professor Rita Effros talks to host Andrea Seabrook about her work with stress and the immune system.

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ANDREA SEABROOK, host:

Stress itself can be a health hazard. The more stressed out you are, the more likely it is that you'll catch that bug going around. A new study now explains exactly how. Dr. Rita Effros is an immunologist and professor at UCLA. She wrote the study. She says it all starts with Cortisol, a hormone we produce when we're stressed.

Dr. RITA EFFROS (Immunologist, University of California Los Angeles): Now, Cortisol is a really good thing, but too much of it is a bad thing.

SEABROOK: Why is it a good thing?

Dr. EFFROS: It works really well in a short-term stress. Let's say you're an animal, running away from a tiger in the forest, and you know that if you don't run fast enough, he's going to get you for dinner.

So Cortisol in your blood stream does lots of good things. It sharpens your cognition. You think fast, you strategy. It slows down you digestion because you really don't need to digest your food when you're running away from death. It slows down your immune system, and it brings energy to your muscles so you can run faster.

So in the short term, Cortisol really does a lot of good things. The problem is if Cortisol stays high in your blood stream for long periods of time, all those things that got shut down short term stay shut down, for example your immune system.

SEABROOK: Okay, so if the tiger in the modern world is, say, an interview with Kevin Costner that I'm not going to run from and have to sit across the table from the man, those Cortisol levels just stay high?

Dr. EFFROS: That's right. It could stay high and slow down things that you don't want to slow down necessarily, and you just mentioned an interview. That could take a half hour, let's say, but let's say you were taking care of an Alzheimer's spouse or a chronically ill child. Those kinds of situations are known now to cause chronic, really long-term stress, let's say years of stress.

SEABROOK: So what exactly happens when the Cortisol is in your blood? What does it do?

Dr. EFFROS: Let me back up for a moment.

SEABROOK: Sure.

Dr. EFFROS: The stressed-our moms of chronically ill children were found to have a funny thing happening in their white blood cells. A certain part of the cell called the telomere, which is a kind of a clock that keeps track of how hard the cell has been working, their telomeres got shorter and shorter, and it's been known for many years that when cells have very short telomeres, they don't function the way they're supposed to function, including immune cells, and it turns out that immune cells have a way to slow down that clock ticking, and that's a protein they can produce called telomerase, and what our studies showed, actually, is at least in a laboratory dish, if you put Cortisol with white blood cells, they do not produce the same amount of telomerase as cells that don't have Cortisol in their environment.

So this kind of explains why, under stress, if that Cortisol is high in our blood, that might be doing the same thing in our bodies, in other words not allowing our immune cells to kind of regulate their telomere length.

SEABROOK: So you're coming up something like a pill that could help people keep their cells healthy and happy and young?

Dr. EFFROS: Well, that's the ultimate goal. Right now, we're looking at sort of the basic science end of things. It will take a long time, but we're not working in the dark anymore. We have some idea what the target is.

SEABROOK: Dr. Rita Effros is a professor of pathology and laboratory medicine at UCLA's David Geffen School of Medicine. Thanks very much.

Dr. EFFROS: Thanks, nice talking to you.

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