Stress
and Disease: New Perspectives
By Harrison Wein, Ph.D.
For thousands of years, people believed that
stress made you sick. Up until the nineteenth century, the idea that
the passions and emotions were intimately linked to disease held sway,
and people were told by their doctors to go to spas or seaside resorts
when they were ill. Gradually these ideas lost favor as more concrete
causes and cures were found for illness after illness. But in the last
decade, scientists like Dr. Esther Sternberg, director of the
Integrative Neural Immune Program at NIH's
National Institute of Mental Health (NIMH), have been rediscovering the
links between the brain and the immune system.
The Immune System and the Brain
When you have an infection or something else that causes
inflammation such as a burn or injury, many different kinds of cells
from the immune system stream to the site. Dr. Sternberg likens them to
soldiers moving into battle, each kind with its own specialized
function. Some are like garbage collectors, ingesting invaders. Some
make antibodies, the "bullets" to fight the
infectious agents; others kill invaders directly. All these types of
immune cells must coordinate their actions, and the way they do that is
by sending each other signals in the form of molecules that they make
in factories inside the cell.
"It turns out that these molecules have
many more effects than just being the walkie-talkie communicators
between different kinds of immune cells," Dr.
Sternberg says." They can also go through the
bloodstream to signal the brain or activate nerves nearby that signal
the brain."
These immune molecules, Dr. Sternberg explains, cause the
brain to change its functions. "They can induce a
whole set of behaviors that we call sickness behavior. . . . You lose
the desire or the ability to move, you lose your appetite, you lose
interest in sex." Scientists can only speculate
about the purpose of these sickness behaviors, but Dr. Sternberg
suggests that they might help us conserve energy when
we're sick so we can better use our energy to
fight disease.
These signaling molecules from the immune system can also
activate the part of the brain that controls the stress response, the
hypothalamus. Through a cascade of hormones released from the pituitary
and adrenal glands, the hypothalamus causes blood levels of the hormone
cortisol to rise. Cortisol is the major steroid hormone produced by our
bodies to help us get through stressful situations. The related
compound known as cortisone is widely used as an anti-inflammatory drug
in creams to treat rashes and in nasal sprays to treat sinusitis and
asthma. But it was't until very recently that
scientists realized the brain also uses cortisol to suppress the immune
system and tone down inflammation within the body. |
Stress and the Immune System
This complete communications cycle from the immune system to
the brain and back again allows the immune system to talk to the brain,
and the brain to then talk back and shut down the immune response when
it's no longer needed.
"When you think about this cross-talk,
this two-way street," Dr. Sternberg explains,
"you can begin to understand the kinds of illnesses that might result
if there is either too much or too little communication in either
direction."
According to Dr. Sternberg, if you're
chronically stressed, the part of the brain that controls the stress
response is going to be constantly pumping out a lot of stress
hormones. The immune cells are being bathed in molecules which are
essentially telling them to stop fighting. And so in situations of
chronic stress your immune cells are less able to respond to an invader
like a bacteria or a virus.
This theory holds up in studies looking at high-levels of
shorter term stress or chronic stress: in caregivers like those taking
care of relatives with Alzheimer's, medical
students undergoing exam stress, Army Rangers undergoing extremely
grueling physical stress, and couples with marital stress. People in
these situations, Dr. Sternberg says, show a prolonged healing time, a
decreased ability of their immune systems to respond to vaccination,
and an increased susceptibility to viral infections like the common
cold. |
Some
Stress is
Good
People tend to talk about stress as if
it's all bad. It"s not.
"Some stress is good for
you," Dr. Sternberg says. "I
have to get my stress response to a certain optimal level so I can
perform in front of an audience when I give a
talk." Otherwise, she may come across as lethargic
and listless.
But while some stress is good, too much is not good.
"If you're too stressed, your
performance falls off," Dr. Sternberg says.
"The objective should be not to get rid of stress
completely because you ca't get rid of stress
-- stress is life, life is stress. Rather, you need to be able
to use your stress response optimally."
The key is to learn to move yourself to that optimal peak
point so that you"re not underperforming but
you're also not so stressed that
you"re unable to perform. How much
we're able to do that is the challenge, Dr.
Sternberg admits. This may not be possible in all situations, or for
all people, because just as with the animals Dr. Sternberg studies,
some people may have a more sensitive stress response than others.
"But your goal should be to try to learn
to control your stress to make it work for you,"
Dr. Sternberg says. "Don't
just think of getting rid of your stress; think of turning it to your
advantage." |
Controlling the Immune Response
Problems between the brain and the immune system can go the
other way, too. If for some reason you're unable
to make enough of these brain stress hormones, you
wo't be able to turn off the immune cells once
they"re no longer needed.
"There has to be an exit strategy for
these battles that are being fought by the immune system, and the brain
provides the exit strategy through stress
hormones," Dr. Sternberg says.
"If your brain can't make
enough of these hormones to turn the immune system off when it
doesn't have to be active anymore, then it could
go on unchecked and result in autoimmune diseases like rheumatoid
arthritis, lupus, or other autoimmune diseases that people recognize as
inflammation."
Dr. Sternberg says that there are several factors involved in
these autoimmune conditions. There are many different effects that the
brain and its nervous system can have on the immune system, depending
on the kinds of nerve chemicals that are being made, where
they"re being made, what kind of nerves they come
from, and whether they're in the bloodstream or
not. Still, at least part of the problem in these diseases seems to
involve the brai's hormonal stress response.
"So if you have too much stress hormone
shutting down the immune response, you can't fight
off infection and you"re more susceptible to
infection," Dr. Sternberg concludes.
"Too little stress hormones and the immune
response goes on unchecked and you could get an inflammatory
disease." |
Pinpointing the Problems
Why these miscommunications between the brain and the immune
system come about is still largely unknown, and involves many genes and
environmental factors. But by studying animals, scientists have finally
been able to start understanding how the miscommunications occur.
Dr. Sternberg first started publishing work on the links
between the brain and the immune system back in 1989 studying rats with
immune problems. "In many of these cases
it's very hard to show the mechanism in
humans" Dr. Sternberg explains,
"but you can show the mechanism in animals because
you can manipulate all the different parts of the system and you can
begin to understand which parts affect which other
parts." It has taken "a good
ten years" to gather enough evidence in human
studies to show that the principles her lab uncovered in rats were also
relevant to human beings.
Drugs that have been tested in rats to correct brain/immune
system problems have had unpredictable effects. That is because nothing
happens in isolation when it comes to the brain and the immune system.
Dr. Sternberg points out that our bodies are amazing machines which at
every moment of the day are constantly responding to a myriad of
different kinds of stimuli -- chemical, psychological, and
physical. "These molecules act in many different
ways in different parts of the system," she says.
Understanding how the brain and the immune system work together in
these different diseases should help scientists develop new kinds of
drugs to treat them that would never have occurred to them before. |
Taking Control
Now
Dr. Sternberg thinks that one of the most hopeful aspects of
this science is that it tells us it's not all in
our genes. A growing number of studies show that, to some degree, you
can use your mind to help treat your body. Support groups, stress
relief, and meditation may, by altering stress hormone levels, all help
the immune system. For example, women in support groups for their
breast cancer have longer life spans than women without such
psychological support.
There are several components of stress to think about,
including its duration, how strong it is, and how long it lasts. Every
stress has some effect on the body, and you have to take into account
the total additive effect on the body of all stressors when considering
how to reduce stress.
Perhaps the most productive way to think about stress is in
terms of control. Dr. Sternberg shows a slide of an F-14 jet flying
sideways by the deck of an aircraft carrier, its wings completely
vertical. "The Navy Commander who flew that jet
told me that he was the only one in the photo who was not stressed, and
that"s because he was the one in control. The
officer sitting in the seat ten feet behind him was in the exact same
physical situation but was not in control. Control is a very important
part of whether or not we feel stressed.
So if you can learn to feel that you're
in control or actually take control of certain aspects of the situation
that you're in, you can reduce your stress
response." Studies show that gaining a sense of
control can help patients cope with their illness, if not help the
illness itself.
Until science has more solid answers, it
can't hurt to participate in support groups and
seek ways to relieve stress, Dr. Sternberg says. But what you need to
remember is if you do these things and you're not
successful in correcting whatever the underlying problem is,
it's not your fault because
there's a biology to the system." You need to know the benefits of the
system," she says," but its
limitations as well." In other words, try not to
get too stressed about being stressed." -- a report from The
NIH Word on Health, October 2000
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A Word to the Wise...
Stress Control
First try to identify the things in your life that cause you
stress: marital problems, conflict at work, a death or illness in the
family. Once you identify and understand how these stressors affect
you, you can begin to figure out ways to change your environment and
manage them.
If there's a problem that can be solved,
set about taking control and solving it. For example, you might decide
to change jobs if problems at work are making you too stressed.
But some chronic stressors ca't be
changed. For those, support groups, relaxation, meditation, and
exercise are all tools you can use to manage your stress. If nothing
you do seems to work for you, seek a health professional who can help.
Also seek professional help if you find that you worry excessively
about the small things in life.
Keep in mind that chronic stress can be associated with
mental conditions like depression and anxiety disorders as well as
physical problems. Seek professional help if you have:
Difficulty sleeping |
Changes in appetite |
Panic attacks |
Muscle tenseness and soreness |
Frequent headaches |
Gastrointestinal problems |
Prolonged feelings of sadness or
worthlessness |
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Feb-05-2023
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