Stress And The Immune System

Method: Monkeys were put in pairs and given electric shocks every 20 seconds for 6 hours. One monkey of each pair ('the executive') could push a lever to postpone eachshock. The other could not delay them.

Results:The 'executive' monkey were more likely to develop illness (ulcers) and later die.

Conclusions: The illness and death was not due to the shocks but to the stress that the executives felt in trying to avoid them. In the long term, this stress reduced te immune system's ability to fight illness.

Evaluation: The experiment has ethical issues- the experiment was very cruel and would not be allowed today. Also we can't generalise results from monkeys to humans.Furthermore we know that people with little control over their own lives (such as those with low level jobs and the long-term unemployment), can experience high levels of stress, which this research cannot explain.

Method: In a study with an independant measures design, a punch biopsy was used to create a small wound on the arms of 13 women who cared for relatives with Alzheimers disease (a very stressful responsibility). A control group of 13 people also took part.

Results: Wound healing took an average of 9 days longer for the carers than those in the control group.

Conclusion: Long-term stress impaires the effectiveness of the immune system to heal wounds.

Evaluation: Sweeny (1995) also found that people caring for relatives with dementia took longer than a control group to heal their wounds. However, for both studies the two groups may have varied in othe ways apart from the stress of being a carer. The effects on the carers could be due to lack of sleep, poor diet etc, and not just the stress they experienced. The study only contained a small amount of participants- for more reliable results it should be repeated with a larger number.

Method: In a laboratory experiment, 39 participants did one of these stress inducing tasks (a maths test, a stroop test and public speaking). Their blood pressure and the extent to which the vessels around their heart contracted (low,medium or high myocardial ischaemia) was measured. Partcipants were instructed not to take any prescribed heart medication prior to the study.

Results: Participants with the greatest myocardial ischaemia showed the highest increases in blood pressure. A small number participants who showed mild or no myocardial ischaemia only had very moderate increase in blood pressure.

Conclusion: Stress may have a direct influence on aspects of body functioning, making cardiovascular disorders more likely.

Evaluation: Although the effects were clearly linked to stress, it can't be said that one causes the other. Also it wasn't shown whether the effects also occur at other times. They might sometimes happen even if the person feels relaxed- and therefore couldn't just be linked to feeling stressed. Not everybody showed the same reactions, which suggests individual differences between the participants may also have played a role. The ecological validity of the study was reduced because it took place under laboratory conditions that weren't fully representative of real-life stress. However, the findings of the study are supported by Williams (2000)- it was seen that people who got angry easily or reacted more angrily to situations had a higher risk of cardiovascular problems.