Outline and evaluate research into the relationship between the immune system and Stress-related illness. (12marks)
It is suggested that stress can result in immunosuppression which can lead to stress-related illnesses such as Coronary Heart Disease and high blood pressure.
Kiecolt and Glaser conducted an experiment to see the effects of stress on the immune system. This was achieved by taking blood samples of 75 medical students one month before and during their examination period. They then compared the two blood samples and found decreased leucocyte activity in the sample taken during high levels of stress (during their exams). This shows that stress reduces the activity of the immune system, making them more susceptible to becoming ill.
Advantages of the study are that blood tests are objective measurements, so there was no social desirability or experimenter bias when analysing the results. The participants were also compared to themselves which removes participant variables on how they perceive stressors. The experiment was a field experiment so there was no manipulating of the independant variable to deliberately cause stress to the participants which makes it ethical. It also means the research has ecological validity and can be applied to the wider world. However, a field experiment may have extraneous variables which impact the results. For example, the student lifestyle of having little sleep and poor accomidation may have been an alternative source of stress. Another disadvantage is that there was a biased sample used of students. It may not be possible to generalise students’ response to stress compared to the general population.
Riley also did a study using rats on a rotating turntable for five hours. He found that over time, their white blood cell activity dramatically decreased and when injected with carcinogens they developed tumours more