When Stress Is Good for Your Health

April 6, 2005 — -- Here's one of those fly-in-your face scientific findings: Some forms of stress may actually be good for you.

For about a decade now scientists at Ohio State University have turned out one study after another showing how stress can suppress the human body's immune system, thus leaving us more vulnerable to viruses like the flu. So it's little wonder they were a bit astounded when they discovered recently that at least one form of stress actually enhances the immune response in mice, and quite likely, in humans.

"We were kind of taken aback [by our findings]," says John Sheridan, professor of oral biology at the university in Columbus.

His colleague David Padgett puts it even more bluntly. "It's absolutely surprising," he says.

If further research supports these early findings it may be possible to develop far more effective flu vaccines, especially for the elderly. But first, the scientists have to figure out what the heck is going on here.

"We really don't know the mechanisms yet," Sheridan says. "We're in the process of trying to understand why."

Fighting Foes Helps Fight Viruses

What appears to be happening, according to another of their colleagues, Jacqueline Wiesehan, is that the type of stress used in the research enhanced the cellular memory of a flu vaccine, thus increasing the ability to deal with a subsequent exposure to the actual virus. In other words, when the real thing came along, the mice more easily recognized it and were better able to fight it off.

The animals we have to thank for this bit of knowledge include a bunch of mice that were bullied repeatedly by a mouse with a nasty disposition for a couple of hours for six consecutive days. At the end of that period the researchers infected the persecuted mice with a strain of influenza that also infects humans. Other mice, not subjected to the bullying, were also infected so the scientists could measure the effects of the stress.

The researchers thought they were creating chronic stress, such as that experienced by a longtime caregiver who has to watch over a loved one every moment of every day. That kind of stress has been shown over and over again to suppress immune systems, thus contributing to the decline in the health of the caregiver.

But the surprise came when the bullied mice were actually better able to ward off the virus than the ones that had not had to deal with an aggressive foe.

So the first thing the scientists did was change the name of the stress test.

"We don't call it chronic, and we don't call it acute," because both are known to suppress the immune system, Sheridan says. "We're just calling it repeated defeat."

By whatever name, the stress apparently improved the memory of the special cells, called "T cells," that run the immune system.

Ingredients for a Vaccine?

In retrospect, the scientists say, the finding should not have been as surprising as it was.

"When you sit down and think about it, you think there should be some benefit to an organism in stress responses," says Padgett, noting that evolution has equipped us to deal with all sorts of incidents through a stress response.

Low levels of stress produce hormones that help us meet various challenges, so a little of a bad thing can be good, but chronic stress produces an overabundance of those same hormones, and that literally can be fatal. It's a major cause of heart disease, for example.

The researchers have high hopes that their work will lead to more effective vaccines. That could have special implications for the elderly.

"Elderly individuals don't respond well to exposure to a vaccine, so they don't generate a good immune response," says Padgett. Maybe, he adds, their cells just don't remember the vaccine, so they are unable to recognize the virus, leaving them with their defenses down.

The next step is to unravel the mechanisms and the physiology at work here. Then, perhaps vaccines can be modified so that they can stimulate the cellular memory.

Of course, there's still some question about whether humans will react the same as mice, but there's reason to be optimistic.

"The mouse immune response is quite comparable to that of the human," Padgett says. "that's why we chose it."

However, none of the researchers thinks it's a good idea for us to expose ourselves to a little stress so we can avoid the flu.

"I wouldn't do that at all," Padgett says. "I try to avoid stress at all costs."

Lee Dye's column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.

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