Stress: New research links stress to course of diseases

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Apr. 9, 2004. 01:00 AM

Stress: An insidious, ubiquitous assassin

New research links stress to course of diseases

Delicate balance of body systems may be disrupted

JANE ALLEN

LOS ANGELES‹As a high-level executive for a large computer manufacturer, Dan

Bishop was a self-described workaholic who thought he was ably juggling

daily demands and corporate pressures. Then he woke up one night with

tightness in his chest, barely able to breathe. At first he suspected a

heart attack. The tightness quickly passed, but he was frightened enough to

see his doctor.

The doctor diagnosed an anxiety attack ‹ caused by stress ‹ and told him to

" stop being so driven. "

" I didn't know what stress was; I didn't think I had stress, " said Bishop,

now 52, referring to the 1990 diagnosis.

As Bishop found, stress can be insidious.

It can be devastating to the body. And it can kill.

Scientists are only now beginning to understand what happens when stress

disrupts the delicate interplay between the brain, the endocrine system ‹

the glands and organs that make and release hormones ‹ and the immune

system, stimulating the release of compounds that cause inflammation.

Recent research has identified some of the ways in which stress influences

the course of illnesses linked to viruses, aging or the body's misguided

attack on its own tissues.

For example, physical or mental stress can take an enormous and sometimes

deadly toll on the heart. It increases blood pressure, narrows blood vessels

and causes blood to become stickier and more likely to clot, increasing the

likelihood of a heart attack or stroke.

In February, a study published in the American Journal Of Psychiatry showed

that stress and depression in heart attack patients increase amounts of

chemicals that make certain immune cells sticky and help them travel to

artery linings, where they produce inflammation and promote coronary artery

disease.

A study published last week in the journal Circulation found that mental

stress also triggers irregular heartbeats, which can be deadly.

" Numerous studies show that psychological stress can lead to illness, or

even death, " said Dr. Irwin, director of the Norman Cousins Center

for Psychoneuroimmunology at the University of California, Los Angeles'

Neuropsychiatric Institute. " How we cope with stress and whether or not we

get depressed is crucial for our health.''

The pressures of daily life ‹ jobs, relationships, money, raising children

and now, war and terrorism ‹ have become such constant companions that many

of us operate with ever-present feelings of pressure, anxiety or burnout.

The stress can become so unflagging that many people have accepted it as a

standard part of life. Although we may try to ignore its presence, stress

doesn't go away. It just goes to work inside the body.

Prolonged stress contributes to many physical and psychological ills. It

overrides natural defences against viruses that cause AIDS, chickenpox and

the common cold.

It also encourages the production of inflammatory hormones that drive heart

disease, obesity and diabetes; sparks flare-ups of rheumatoid arthritis and

digestive disorders; creates depression and ages the brain.

Unchecked stress sends out complex signals that unleash a cascade of

activity throughout the body.

When someone is confronted with stress ‹ whether physical or psychological ‹

the brain is the first part of the body to respond, reacting in two distinct

ways.

In one of the reactions, a regulatory part of the brain called the

hypothalamus sends signals through sympathetic nerves near the spinal cord

to the adrenal glands, commanding them to release the stress hormones

epinephrine and norepinephrine (also called adrenaline and noradrenaline).

These hormones gird the body for action. They boost heart rate, blood

pressure, breathing and blood flow to the muscles and brain, providing an

extra surge of energy in times of physical danger. They can also keep

athletes, entertainers and others on their toes, keeping them alert and

productive when performance counts.

But chronic stress opens the floodgates to epinephrine and norepinephrine,

regardless of whether there's a threat, allowing bacteria, viruses or

tumours to flourish and making blood more prone to clotting.

The brain's other reaction comes through the pituitary gland, which sends

signals through the bloodstream instructing the adrenal glands to release

the stress hormone cortisol and other steroids. In the right amounts,

cortisol helps the body recharge, enhances disease resistance, fights

inflammation and improves memory.

In excess, however, cortisol promotes the accumulation of abdominal fat,

suppresses immunity, shrinks brain cells and impairs memory.

Over time, cells become less sensitive to the protective effects of

cortisol, and inflammation goes unchecked.

Stress can certainly give you butterflies or a stomach ache, but chronic

stress can trigger flare-ups of irritable bowel syndrome, an intestinal

condition that includes cramping, gas, diarrhea and constipation.

Women with the condition (who vastly outnumber men) not only have elevated

levels of cortisol, but also have exaggerated differences between the higher

morning and lower evening levels found in healthy people, Italian

researchers reported in 2001.

Although stress is no longer believed to cause ulcers (they're sparked by an

infection of the bacterium H. pylori), it can worsen symptoms.

HIV-infected gay men who keep their sexual orientation secret get sicker and

have shorter life spans than gay men who are more open about their

sexuality, a 1996 study found. Closeted gay men tend to be shyer and their

nervous systems overreact to stress; as a result, their bodies pump out more

stress hormones, which encourage the virus to multiply.

People who suffer from rheumatoid arthritis, an autoimmune disease of the

joints, already have high levels of hormones called inflammatory cytokines,

which cause swelling, pain and inflammation. Stress and depression, which

can intensify pain and create more physical limitations, further increase

those levels, according to a study in the March issue of the Journal Of

Rheumatology.

As their understanding of the biochemistry of stress increases, scientists

are developing and testing ways to protect the body from its ravages, using

yoga and meditation, psychotherapy and medications, and even experimental

devices.

Among the simpler interventions that hold the most promise is tai chi, a

centuries-old Chinese exercise often described as " meditation through

movement. "

In a study of adults older than 60, UCLA researchers found last year that

one type of tai chi improves immunity to shingles, a painful nerve disease

caused by the re-emergence of the chickenpox virus.

Medications may also prove effective at blocking the destructive effects of

stress hormones. For example, Cole and his colleagues have just started a

study in which they're giving beta blockers, which are typically prescribed

for hypertension and heart disease, to HIV patients. The drugs should block

the ability of stress hormones to make HIV multiply, the researchers say,

thus lowering viral loads.

Other medications, such as antidepressants and anti-anxiety drugs, alter the

brain biochemistry that makes some people overreact to stress.

Dr. Tracey, head of the Center for Patient-Oriented Research at the

North Shore-Long Island Jewish Research Institute in Manhasset, N.Y., has

been using vagus nerve stimulation to decrease inflammation in disorders

aggravated by stress, including rheumatoid arthritis. The vagus nerve

controls involuntary functions such as heart rate, respiration, digestion

and bladder function. Stimulating the vagus nerve to slow the heart rate, in

this case with a pacemaker-like device, is also the basis of biofeedback and

meditation.

Researchers at several institutions are experimenting with rapid

transcranial magnetic stimulation, which delivers electromagnetic waves

through a device placed against the roof of the mouth, to treat anxiety

attacks and other manifestations of chronic stress.

But, cautioned Dr. Rosch, president of the American Institute of Stress

in Yonkers, N.Y.: " Just as stress is different for each of us, there is no

stress-reduction strategy that's a panacea. "