So you think stress is all in the mind?

by Rob Gilhooly

It’s as inevitable and, in most cases, as unwelcome as that overcrowded rush-hour train. Stress: We’re all its victims to some degree. But do we know what causes it, and what its long-term effects on the body can be?

At its most basic level, human stress is emotional change, or the impairment of homeostasis that may result from interaction with the environment. In other words, stress is tension — whether physical or mental — brought about by external factors. Physical factors can include the likes of exposure to extreme temperatures, injury or shock; psychological ones can range from marital breakdown to stage fright.

But not all stress is bad. Exercise produces temporary physical stress, but its benefits are undeniable — unless you have an undiscovered heart condition. Occasional stress can also be useful and productive if we have a way of channeling the energy it creates.

“Whether a stimulus induces excitement or distress, we undergo the same physiological reaction,” said Nozomu Asukai of the Stress Disorders Research Department of the Tokyo Institute of Psychiatry.

“However, what we now think of as stress is mostly the ‘distress’ variety, the kind that brings about psychosomatic or psychological effects. But Olympic athletes experience a kind of nervousness that can act as a motivator — this, too, is stress.”

In response to a challenging event, glands secrete hormones such as epinephrine into the bloodstream. This gives us an energy boost and prepares us to respond — to fight or flee. As a result, our heart rate surges, blood pressure rises and our pupils dilate; we become ultra-vigilant.

Another hormone, cortisol — sometimes termed the “stress hormone” — is produced by the adrenal glands, and this converts glycogen stored in the liver into blood sugar to provide increased energy. At the same time, blood is also diverted away from the stomach to free up more energy, thus causing the digestive tract to shut down — which is why continued exposure to stress can lead to ulcers.

This adrenal activity was important for our ancient ancestors, for whom a fight or flight response was essential for survival. Though modern “stressors” are more likely to be wild-card bosses and invasive PCs than wild animals and invading clans, our response system remains the same. And rather than being occasional nuisances, stressors today are often as persistent as they are multifarious. Worse still, many are intangible.

Although cause and effect are difficult to pin down precisely, clinicians are in no doubt that continual exposure to stressors can have damaging — or even fatal — medical consequences. One study, published this year by the University of Pittsburgh, found that people facing combined factors of severe workplace stress and marital strife were around 70 percent more at risk of dying from heart disease than those not troubled by these stressors.

Research at a medical school in Nagoya also linked workplace stress to “sudden cardiac death.”

Asukai explained that the biochemical basis for this danger lies in the autonomic nervous system’s inability to distinguish between various stressors. Consequently, emotional stressors, such as those that induce anxiety, will set off the same sequence of reactions in our bodies as if we were being chased by a big, angry dog. In the former case, however, the counteraction the body automatically prepares for may never take place. As a result, the released stress hormones are left to build up, and at the same time the body continues its efforts to adapt to the increasing strain.

Ultimately, if that pressure remains unreleased, exhaustion sets in and breakdown occurs, Asukai said, with the body’s immune system being greatly weakened in extreme cases.

In fact, it is now more than 50 years since U.S. scientists first demonstrated that rodents subjected to stressful stimuli were more likely to develop viral infections than their non-stressed counterparts. Last year, research at an Ohio medical university made the further discovery that stress may increase the chance of skin wounds becoming infected.

In addition, immune-system breakdown caused by stress has also long been connected with an increased risk of cancer, while atopic (inherited, allergic) diseases such as asthma and dermatitis are said to be exacerbated by psychological stress. This is also thought to be a direct cause of nicotine, alcohol and other drug abuses.

As if all this weren’t enough, elevated levels of cortisol can lead to depression, which can lead to suicide.

Meanwhile, the mounting pressure caused by undischarged hormonal secretions can also trigger psychosomatic problems such as sleep disorders, irritability and aggressive behavior. Experiments have shown that mice kept in a stressful environment become increasingly aggressive and eventually inflict harm on each other, Asukai commented.

“It is not difficult to see how mothers who are isolated and unsupported by their spouses could become stressed-out and aggressive toward their children,” Asukai said. As the number of people in this situation is increasing in Japan — the decline of the extended family system often robs mothers of vital support — this may be a factor in the increased incidence of child abuse, which has jumped twentyfold in the past decade.

Other conditions thought to result from psychological stress include bruxism, the habit of grinding or clenching the teeth, particularly during sleep; temporomandibular disorders (trouble with opening and closing the jaw); irritable bowel syndrome; eating disorders; and techno-anxiety.

Of course, all this costs — and not just on a personal level. In the U.S., for instance, stress-related illness (including the likes of repetitive strain injury) is estimated to cost the economy $150 billion a year, while in Britain the number of occupational stress-related cases entering the courts jumped more than 12-fold from 2000-2001, reaching 6,000, with payouts totaling more than 320 million British pounds.

While similar statistics for Japan are unavailable, a study last year by the Ministry of Health, Labor and Welfare of 114,000 inpatients entering Toyko hospitals on a given day, found that 22 percent were suffering from psychiatric and stress-related disorders — a close second to the 23 percent suffering from heart diseases.