257 men in their study died from heart attacks - 70% of those who died had been judged as having ‘type A’ personalities.
Critics have argued that it is very difficult to decide if someone has a ‘type A’ personality or not.
They also say that the connection between personality and heart disease is weak, maintaining that negative emotions such as anger and frustration are more linked to stress-related illness than ‘workaholic’ lifestyles. These emotions may not be fixed aspects of someone’s personality.
In the late 1970’s, Kobasa came up with a theory of why some people suffer stress more easily than others, suggesting that some people are ‘hardy personality types’.
These people have a sense of personal control over their lives, a sense of purpose and they view life events as challenges rather than stresses. Such people report less stress-related illness.
b) Outline findings of research into the role of ‘control’ in stress.
Brady carried out a notorious experiment in the 1950s called ‘the executive monkey experiment’ to see how ‘executive stress’ was related to control of a situation. Stress was measured by the amount of stomach ulcers suffered by the monkeys when placed in conditions in which they were given repeated electric shocks at regular intervals.
Brady found that ‘executive monkeys’, who had the power to turn off the electric shocks, developed greater ulceration than ‘passive monkeys’ who were dependent on their ‘executive’ partners to stop the shocks for them.
Weiss, however, repeated this study with rats using a warning bell to let them know when a shock was about to arrive - giving them an extra level of control - this was found to reduce stress-related symptoms.
In the 1970s, Seligman carried out another control-related study and came up with the idea of ‘learned helplessness’.
Seligman found that when animals had experienced inescapable electric shocks, they did not escape later even when they were given the chance to.
This phenomenon also occurs in humans in response to loud noise. Seligman’s work suggested that if life seems uncontrollable, it could lead to symptoms of depression - and depression is often stress-related.
c) To what extent does research support a link between stress and the immune system?
Kiecolt Glaser et al (1995)
Kiecolt Glaser et al carried out a study to find out the direct effects of stress on the immune system by looking at how quickly wounds heal.
He used women who were caring for relatives suffering from senile dementia, a task which has been shown to be associated with chronic stress.
In order to asses this; a matched paired design was used. It was a volunteer sample. 13 women aged 47-81 were carers placed in the experimental group, and a further 13 were matched with the carers on the basis of age and income but not marital status. This was the control group.
All participants were given a wound – a punch biopsy, which is a cut of 3.5mm just below the elbow. The wounds were all dressed and treated in the same way. The researchers also assessed levels of cytokines- biochemical substances involved in regulating the body’s immune response. Participants were also given a 10-item perceived stress scale to check how stressed they actually did feel.
Complete wound healing took significantly longer in the carers than the controls. It took an average of 9days longer in the carers. It was also found that cytokine levels were lower in the carers then the control group. The carers did also actually indicate that they were feeling more stressed.
The findings supported the view that chronic stress depresses the functioning of the immune system – because wound healing was slower in individuals who experienced chronic stress. The lower levels of cytokines in chronically stressed individuals support the views that stress lowers immune response directly.
Cohen et al (1993) used the ‘viral – challenge’ technique to study the effects of stress on over 400 volunteers. Individuals were exposed to the common cold virus and also given a questionnaire to asses their levels of perceived stress. Cohen et al found positive correlation between levels of stress and the likelihood of catching a cold
Riley (1991) experimented with mice, inducing stress by placing the mice on a rotating turn table. Within 5 hours this lead to a lowered lymphocyte counts. Some mice were implanted with cancer cells. After 3 days of 10 minutes of rotation per hour, mice were more likely to develop tumours than control mice given no stress. This shows that stress reduced immune activity (lymphocyte count) and was related to illness (more tumours).
Kiecolt Glaser et al (1984) looked at t-cell activity in the blood of students taking exams. Levels of t-cell were higher during the month before the students took exams and dropped during the examination period itself.
These findings have important implications for treating people with infections, particularly in situations where people are recovering from surgery. Clearly it would be important to reduce stress as far as possible in such patients and thus speed their recovery.
Therefore research strongly supports that stress does affect the immune system, most of the time weakening it and making us more prone to diseases.
