Outline and evaluate research into the relationship between the immune system and stress-related illness. (12)
Kiecolt-Glaser et al investigated the effect of exams (acute stress) on the immune system. She carried out a natural experiment with 75 medical students and took their blood samples a month before exams, a relatively low stress period and during the exam period (high stress). Their immune system functioning was tested by measuring the levels of NK cell activity. Participants were also given a questionnaire to record any other life stressors such as loneliness. She found that NK cell activity was lower in the 2nd sample compared to the one before exams. She also found that those who reported high levels of loneliness had lower NK cell activity as well. This suggests that acute stressors reduce the functioning of the immune system and therefore increase vulnerability to illness. Kiecolt-Glaser et al also tested the relationship between chronic stress on the immune system by testing the impact of interpersonal conflict on wound healing. They blistered the arms of married couples and found that the wounds healed more slowly on couples who had conflicting discussions. This suggests that chronic stress significantly reduces the body’s ability to heal and increases the likelihood of stress-related illness.
A weakness of the first study is that is low in external validity. This is because the sample Kiecolt Glaser used was only made up of medical students and therefore it isn’t representative of other students or even other people. The sample might have unique characteristics, which means it has low population validity because the results cannot be generalised to other people. Another weakness is that there isn’t a simple relationship between stress and illness. Lazarus suggested that this is because health is affected by many different factors such as genetics and lifestyle, and as a result there may be little left that can be accounted for by stress. Additionally, health is very slow to change and so it is difficult to show that the change is due to stress. Finally, the link between long-term stress and health is impractical and expensive to test so most research has concentrated on relatively short periods of time. A final weakness is that there are individual differences; people respond differently to stress. For example, as people age, stress has a greater effect on immune system functioning, making it harder for the body to regulate itself (Segerstone and Miller). This shows that we cannot generalise the findings of this research to everyone because stress affects everyone differently. However, a strength of this research is that the findings can be applied to the real world. Knowledge of how stress affects immune system functioning has led to many new programmes for a healthy lifestyle and stress-coping behaviours can be taught to groups of all ages and backgrounds. For example, techniques such as deep-breathing and expressive writing about a stressor are taught. People who use these generally report improvement in their well-being. This shows how research into stress and the immune system has helped to develop better, more effective stress-coping strategies.
Outline and Evaluate research into life changes…