I was out running recently when it happened. I was nearing the end of a five-circuit and was feeling very weary. My legs were leaden. Ahead of me I spied a woman with a terrier - I'm a bit nervous of dogs. The terrier was not on a lead. He paid no heed to me as I passed, and I relaxed. But I hadn't gone another 10 yards when I heard an ominous growl. My body reacted instantaneously with the "fight or flight" response (in this case the latter option). First, I felt a jolt in my stomach as the adrenalin hit. My shoulders straightened and my whole posture rose up like a Citroen suspension. The lead vanished like magic from my legs and I strode out like Sonia O'Sullivan kicking down the final straight. After about 10 seconds of magnificent running it became clear to me that the dog was not chasing. My legs filled up again with lead and I stumbled on back to the changing room.
We are all equipped with the fight-or-flight mechanism. It is an instantaneous and involuntary response by the sympathetic nervous system (which controls our automatic functions such as breathing, heartbeat etc.) to any suddenly perceived danger, and it prepares the body to either fight off the adversary or to flee from it.
Heart rate, breathing rate and blood pressure rise. Blood flow to muscles, heart, lungs and brain increases. Hormones are released into the bloodstream and also prepare the body for fight or flight. Energy reserves are mobilised and made available to the muscles.
In order to conserve energy, various body-building processes are slowed down and the immune and reproductive systems are inhibited. As soon as the danger passes, hormone release ceases and the body physiology quickly returns to normal.
The fight-or-flight mechanism was a vital aid to survival in our evolutionary past when acute physical threats were frequent. For most people today such threats occur infrequently, but they nevertheless do occur and the fight-or-flight mechanism remains very important. On another occasion I might have to fight with or flee from a mugger, instead of running from a harmless terrier.
A problem arises, however, when the stress-response mechanism is operated inappropriately and on a chronic basis. Normal everyday living presents us with an ongoing series of difficult choices and problems. Most people take these routine challenges in their stride, and in fact stress at this normal level of intensity is both a necessary and a healthy thing. The fight-or-flight response is not activated by normal background stress.
However, some people do not cope adequately with routine problems. They perceive them as bigger threats than they really are, thereby triggering the fight-or-flight mechanism. As a result of this chronic stimulation, the stress-response hormones, particularly adrenalin and the glucocorticoids, are present in the bloodstream on an ongoing basis. This exerts wear and tear on the body and, in the longer term, predisposes such individuals to increased risk of cardiovascular disease, adult diabetes, ulcers, and generally impaired resistance to disease.
In recent decades it has become clear that people with certain types of personality face a higher risk of developing a stress-related disease because of chronic stimulation of the stress response syndrome.
The main types of personality at risk are depressive-passive types, people with anxiety disorders, Type-A type personalities, excessively determined types, and repressive personalities. In each case there is a mismatch between stress and the coping response to the stress.
The depressive-passive personality does not face up to stress. Many give up without a struggle. They find it very difficult to learn coping strategies. The consequent feelings of hopelessness and helplessness produce elevated levels of stress hormones in the blood.
The life of an anxious personality is filled with threats. Danger lurks around every corner. Life is an endless anticipation of threats against each of which a strategy has to be devised in order to neutralise the danger.
The Type A personality was first described in 1950 and is probably the most widely studied disease-susceptible personality type. This personality is characterised by hostility, cynicism, over-competitiveness, impatience and ambition. They anger quickly, cool down slowly, and interpret difficulties as deliberate attempts to frustrate them.
The most corrosive characteristic of this personality type is probably cynicism. The world is seen to be filled, not with potential friends, but with real and potential enemies. This personality experiences chronic stress which over time demands a substantial cardiovascular price.
The excessively determined type of personality assumes that any obstacle can be overcome by making a sufficiently great personal effort. The predisposition is always to take the hard way out. This attitude is particularly wearing on a person who is born into poor and limited circumstances, where rewards are not so directly linked to personal effort as they are with people born into a more privileged meritocratic world.
In each of the personality types described so far, psychological tests will show either depression, anxiety, hostility and cynicism, or determination to control the uncontrollable.
The tests will also register the subject's unhappiness or dissatisfaction with their lot, and examination of lifestyle and attitudes will readily identify the stressors.
However, there is another personality type that doesn't register as depressed, anxious, hostile/cynical or over-determined on personality tests, that doesn't appear to be subject to many stressors, appears to be happy and successful, but yet has a chronically activated stress response. This is the repressive personality.
Repressive personalities live very orderly lives guided by strictly observed rules. In their black-and-white world behaviours are either permitted or forbidden and a tight rein is kept on emotions. Regulation, hard work and productivity are emphasised. On personality tests such people show a strong distaste for ambiguity, dread of social disapproval and a lack of emotional expression.
So why do repressive personalities, who appear to be mentally healthy, socially integrated, happy and productive, have an overactive stress response? It has been proposed that, because they have to work so hard mentally to maintain their structured repressed world, the effort exacts a heavy physiological price. In support of this proposal, it has been shown that if people are shown graphic film of cardiac by-pass surgery, for example, there is a strong arousal of the sympathetic nervous system. However, the arousal is even stronger if people are shown the film but told to hide their emotions. Trying to exert too much psychological control is physiologically debilitating.
We are each handed our biological constitution as a given, and we have little control over many childhood experiences that have a shaping influence on personality. However, as adults we have the power to change ourselves. If you have a problem with stress the first step towards recovery is to understand the situation. I have briefly explained the physiological consequences of coping inadequately with normal levels of stress, and of the types of personality particularly at risk.
There are many self-help books that outline strategies to acquire and improve skills for coping with stress. If you find that stress is a significantly debilitating factor in your life and that your personal efforts to improve are not working, professional assistance is available through a clinical psychologist or a psychiatrist.
An interesting book on stress is Why Zebras Don't Get Ulcers: A Guide to Stress, Stress- Related Diseases and Coping by R.M. Sapolsky (W.H. Freeman, 1994). A valuable book to help young people is The Student: A Guide to Success in Second and Third Level Education by M. Dineen and B. McLeavey (Folens, 1992).
William Reville is a senior lecturer in biochemistry at University College Cork