Aims: To test job-strain model (stress due to high and low control)
Procedures: Over 7000 high grade (high job demand) and low grade (low job demand) Civil Service employees (men & woman) rated for cardiovascular disease, coronary risk factors, sense of job control, and amount of social support. Re-assessed 5 years later.
Findings: Higher-grade civil students developed fewest cardiovascular problems. Lower grade civil servants had weaker sense of job control and poorest social support. Cardiovascular disease also related to risk factors (smoking/obesity).
Conclusions: Low control linked to higher stress and CHD. Not fully supporting job-strain model because high demand was not linked to illness.
Criticisms: (i) Can explain findings in terms of SES instead of control/demand; (ii) Biased sample: urban, job-orientated and ambitious
Kiecolt Glaser looked directly at the immune function through the blood. He used women that were under high stress levels due to circumstances such as divorce, caring for terminally ill patients and medical students.
Acute stress: Kiecolt Glaser took blood samples from 75 medical students 1 month before an exam (low stress) and during the exam (high stress). Results showed that NK cell activity was lower in the second sample. This shows that exam stress could lead to vulnerability to illness.
Chronic stress: Kiecolt Glaser tested the impact of interpersonal conflict on wound healing. She found that blister wounds on the arms of married couples healed more slowly after they had discussions, which were conflicting rather than supportive.
Another study for acute stress showing exam related immune change showing a dramatic effect on the rate at which wounds heal. Marucha inflicted a ‘punch biopsy’ in the mouth of students either during the summer holidays or three days before an exam. The wounds given before the exam took 40% longer to heal than the wounds during the holidays.
Meta-analysis: 293 studies over 30 years found –
Short term, acute stressors can boost the immune system, prompting it to ready itself for infections or other challenges in the body,
Long-term stressors led to suppression of the immune system – the most chronic stressors were associated with the most global suppression of immunity.
The longer the stress, the more the immune system shifted form potentially adaptive changes to potentially detrimental changes.
Lazarus argues that health can be affected by many different factors (including genetic influences, lifestyle etc.) Most research has concentrated over short periods of time - health is continuous. Health is also fairly stable and slow making it difficult to demonstrate exposure to particular stressors that have caused a change in health.
Life Changes (Rahe et al):
· To establish a link between stress and reduced immune functioning
· This was based on the assumption that the body’s response to stress decreases immune functioning
· They aimed to establish a difference in immune response between conditions of high and low stress.
· They also aimed to see if other factors such as psychiatric symptoms, loneliness, and life events were associated with immune functioning
· 75 first-year medical students (49 males and 26 females) volunteered (a self-selected sample).
· This was a natural experiment because the IV (the level of stress due to exams) was naturally occurring.
· A repeated measures design was used, with P’s blood samples being taken one month before their final exams (low stress condition) and again on the first day of their final exams (high stress condition)
· The number of natural killer cells and T cells were measured as indicators of immune functioning (the DV), with a high number indicating better immune functioning.
· On both occasions, the students were given questionnaires measuring psychiatric symptoms, loneliness or stressful life events
· Natural killer and T cell activity declined between the low-stress and high-stress conditions
· Therefore, the findings confirm the assumption that stress is associated with reduced immune functioning.
· The findings from the questionnaires revealed that immure responses were particularly suppressed in P’s who reported that they were experiencing psychiatric symptoms, loneliness or stressful life events
· The research shows that stress is associated with immunosuppression and that the effect is stronger when there are multiple sources of stress.
· A number of different sources of stress were shown to contribute to reduced immune functioning; exams, psychiatric symptoms, loneliness, and life events were all implicated.
· However, only associations were established. Implications include the importance of stress management to immune functioning.
· + Because this was a natural study, there are fewer ethical objections.
· + An advantage of this study is that the choice of IV (exam stress) is a long-term form of stress. In previous studies, stress had been artificially induced, which is likely to produce a different type of stress to stress, which is experienced naturally.
· - This was a natural experiment, meaning that the IV was not under the control on the experimenter. As a result, cause and effect cannot be established as the IV is not controlled or isolated (causation can only be established when an IV has been directly manipulated). Therefore it cannot be established that stress causes the immunosuppression.
· - It is important to note that the functioning of the immune system of nearly all the students was still within the normal range, even in the higher stress condition.
· - The immune system is very complex, and so it is hard to be sure that it’s functioning was actually impaired in the higher stress condition. This means that the reliability and the validity of the measure are questionable.