Counter Terror Gazette

Stress Response: a Physiological Analysis

14 Jun 2011

Disruptive passenger incidents can be caused by an individual being in a state of high stress, either due to anxiety / phobia of flying, or due to external life stressors they may be experiencing.  And although rare occurrences, an individual exhibiting manifestations of stress may have criminal intent, such as a hijacking or suicide bombing. Knowing and interpreting the signs of stress can play a crucial role in passenger profiling and the questioning of individuals. What behavioural indicators and body responses indicate that a person is experiencing high stress levels? Siriol Haf Griffiths looks at the human nervous system and highlights what to look out for and why the body responds in such a way.

Dry mouth, headache, poor concentration, lack of sleep, diarrhoea, a shortness of breath. We’ve all been there at one time or another. These are some of the most obvious signs of stress, but they are very wide ranging which begs the question – what exactly is ‘stress’? Is it a physical or an emotional phenomenon? Or both? It transcends a definite label, begging the question – if you cannot define stress, how can you assess it?

THE FIGHT OR FLIGHT RESPONSE

This phenomenon was first described by Walter Bradford Cannon in 1915. According to his theory, animals react to threats with a general discharge of the sympathetic nervous system, which then primes the animal in question for fighting or fleeing. The sympathetic nervous system is one of the parts of the autonomic nervous system. Its job is to mobilise the body’s resources when it’s experiencing stress, i.e. to induce the fight or flight response. An example of the flight response is the grazing zebra. It sees a lion closing in for the kill, which activates the stress response. The zebra’s escape from the lion needs extreme muscular exertion, which is reinforced by the body’s systems. An example of the fight response is a man walking down the street who is confronted by an assailant.  Instead of running, he chooses to fight his attacker.

HANS SELYE

‘Stress’ was a term first coined in 1936 by endocrinologist Hans Selye. At the time he was carrying out biochemical experimentation, involving the injection of rats with ovarian extract. The rats developed a variety of symptoms, which included the enlargement of the adrenal cortex, atrophy of the thymus, spleen, and lymph nodes, and also deep bleeding ulcers in the lining of the stomach and duodenum. Selye at first believed that he’d discovered a brand new hormone. But his belief began to diminish when, first, placental extract and, later, pituitary extract brought about the same symptoms. Next, he injected the extract of kidney, spleen and numerous other organs. They all produced the same effect. He then made a last attempt to clarify these strange results and injected a toxic liquid, Formalin. When even this produced the same symptoms, he knew that he had not discovered a new hormone. But what had he discovered?

Selye remembered his formative years at medical school. During his introduction to clinical medicine, various patients were brought in for examination. He recalled that they all “felt and looked ill, had a coated tongue, complained of more or less diffuse aches and pains in the joints, and of intestinal disturbances with loss of appetite.” He also generalised that they “had fever, enlarged spleen or liver, inflamed tonsils, a skin rash” as well as a number of other symptoms. To Selye, these patients had something in common with his sick rats, and he wanted to find out exactly what. “If there was such a thing as a single nonspecific reaction of the body to damage of any kind,” he writes of his jubilant epiphany, “this might be worth study for its own sake”. He surmised that there must be some sort of mechanism in the body whose response to external agents was somehow general. Hans Selye’s original suspicion and subsequent research identified this internal stress-processing mechanism, which has come to be known as the hypothalamus-pituitary-adrenal system.

The Hypothalamus-Pituitary-Adrenal Axis

The HPA axis is a complex set of direct influences and feedback interactions among the hypothalamus, the pituitary gland (a hormone producing, pea-shaped structure located below the hypothalamus in the brain), and the adrenal glands (small, conical-shaped organs above the kidneys).

This system governs the amount and kind of response the body produces to combat a stressing agent. The hypothalamus – the bridge between the brain and the endocrine system – sends a message to the pituitary gland to release adrenocorticotrophic hormone (ACTH) into the blood stream. This signal prompts the adrenal cortex to create corticoids (another hormone). The corticoids are then dispersed to the places in the body where they are needed, and are put to use in the various stages of defence against a stressing agent. This was the materialisation of Selye’s goals – the identification of stress based upon “demonstrable biological laws”.

With this information in mind, it was possible to begin gauging precisely what the role of stress was in our lives. How, then, can personnel identify a highly stressed passenger?

It is important to keep in mind that no single indicator should, necessarily, be attributed to stress.  Normally, multiple indicators would need to be showing in order to be able to reasonably attribute stress as the cause.  And even then, it may not be down to stress, but to a medical / physiological cause. The experience of flying, from passing through the airport to the experience in-flight, can be at least mildly stressful for many people.  So, for example, someone being impatient at check-in or security may not be a hijacker or a potentially disruptive passenger, but just exhibiting a normal response to a frustrating situation.  A passenger who has to make several trips to the toilet may very well have diarrhoea from food poisoning in a tropical country, not from stress due to mal intent.

The following are indicators of stress, but are not relevant to passenger profiling: hair loss, changes in skin condition, cardiovascular disease, Obsessive Compulsive Disorder, social phobia, detachment, low self-esteem and nightmares. Other signs are relevant to passenger profiling and these are detailed below.

STRESS INDICATORS: Physiological

Chest Pains

Chest pains are normally caused by muscle tension, and pains can make one feel very scared, giving rise to more serious concerns, like a heart attack. This is normally just a conditioned response. Real heart pain is very different to chest pain and very often does not start in the chest.

Headaches

Headaches include a wide range of pain from stabbing pains to light pressure in the face and neck. This is because the blood vessels and nerves in our head and face originate or track through the neck.

Indigestion

Indigestion (as well as stomach cramps, heartburn, diarrhoea or constipation) can be caused during stressful or anxious times. Their cause is due to the body’s response to stress by diverting blood away from the stomach to other muscle tissues, causing the stomach muscles to tighten. It can also work in the opposite way and cause diarrhoea.

Muscle Tightening

This occurs when muscles remain semi-contracted for a long period, and is caused by the blood vessels constriction, reducing blood flow to the soft tissues, muscles, tendons and nerves. A build up of biochemical waste products results in muscle tension and spasms and can lead to back ache. A very visible symptom of this is a facial or eye tick.

Nausea

Feeling sick is a physical sensation which accompanies the urge (but not always leads to) to vomit. Often stress will make a person gag or dry heave.

Shortness of Breath

Experiencing a shortness of breath, or the feeling of not being able to inhale enough air, can be traumatic, and can add to existing stress levels in a vicious cycle.

Sweating

Of course, sweating is a natural reaction to help the body keep cool. During stressful times, the body naturally prepares itself for “flight or fight” mode. Sweat is released to cool the body and divert blood to various parts of the body to deal with the possibility of flight or fight.

STRESS INDICATORS: Emotional

Aggression

This hostile or destructive behaviour usually arises when expectations are blocked, threatened or removed and may arise as a response to frustration. Aggression may manifest as destructive and attacking behaviour, hostility or by a self-expressive drive to control.

Anger

This emotional state can range from irritation to intense fury and uncontrollable rage. The heart rate and blood pressure increases during anger, and it also affects levels of adrenaline and noradrenalin.

Anxiety

Visible signs of anxiety include being fidgety, jumpy, jittery, tense and restless.

Feeling Moody

Moods are all-encompassing and can range from the lowest of lows to the highest of highs. Some negative moods include sadness, feeling lonely, anger, pessimism, irritability or shame. Negative moods can be set-off by major life stressors such as bereavement, the end of a relationship, loss of job etc.

Panic

Panic is a sudden strong feeling of fear that prevents reasonable thought or action, and impairs behaviour. Many things can trigger a panic attack, such as a fast heartbeat, thoughts or memories, or emotions that are associated with panic/fear. For some people, flying will elicit a strong feeling of panic and may lead to illogical, irrational behaviour in-flight.

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