KIECOLT-GLASER'S EXAMINATION STUDENTS, 1984
1: Blood samples were taken from 75 volunteer medical students 1 month before their exams.
2: Blood samples were taken again on the 1st day of their exams.
3: It was found that the natural killer-t cell activity had decreased between these 2 times, lowering the immune system
4: This was particulary evident in those students who were lonely and experiencing stressful lives
- Concentrates on a short period of time and doesn't measure illness outcomes - were there any long term changes? Did it effect the grade?
- Only measures 1 component of the complex immune system
- Natural study
- Ethical issue: Protection from harm - pain when taking blood samples so needs fully informed consent and approval from an ethics committee
KIECOLT-GLASER'S CARERS OF ALZHEIMER'S PATIENTS, 1
Experimental Group: Women looking after a relative with alzheimers (they wanted to see if psychological stressors can cause damage to the immune system)
Control Group: Women matched in age and family income to the carers
- The carers scored highest on the perceived stress scale
- Then, a small wound was created in the arms of all participants
- They measure the healing by photographing the wound reglary and observing the response to hydrogen peroxide - absence of foaming indicated healing
- The caregiver's wounds took the longest to heal: 48.7 days
- Natural study
- Ethical issue: Protection from harm - small wounds involve pain so full informed consent and approval from ethics committee is required
COHEN'S COLD VIRUS, 1991
1: Cohen's participants (394 of them) received nasal drops containing cold viruses at the beginning of the trial
2: The researchers were measuring stress levels and the extent to which they felt out of control, as both these things are associated with increased stress
3: They found that the participants with the highest levels of stress were twice as likely to develop colds. In total, 82% caught cold.
4: Also, those with fewer than 3 social roles were 4 times as likely to catch a cold from the drops
- Only correlational evidence found - can't establish cause and effect
- Doesn't say which element of stress and what component is the most important in catching cold
- Ethical issues: Informed consent: Participants should be in good health before hand
1: Mice were placesd on a rapidly rotating turntable for 5 hours.
2: He measured their lymphocyte count and found that it had decreased
1: Cancer cells were put into the mice and they were either exposed or not to the "stress condition":
- 10 minutes of rotation per hour for 3 days
2: With no stress condition, tumour growth stopped
With stress condition: they developed large tumours
- Concentrated on a short period of time
- Measured only 1 component of the immune system
- Most studies are short term, but, effects on health may take some time to show
- Most studies are correlational so we cannot make a cause and effect claim as there might be another factor involved, eg, in the caregiver study, they might be on medication
- Also been found that stress is affected by many factors such as genetics and lifestyle. The direct effect of stress is only a small part of the story about what makes us ill