KeyStudyImmune


Key study

 

Stone et al. (1987)

 

Stress and the immune system

 

Aim

The aim of the study was to see if stressful events in everyday lives would make people more susceptible to upper-respiratory tract infections (i.e. colds). Since there is an incubation period, if stress does suppress the immune system, then symptoms should occur several days after exposure to stress.

 

Procedures

The researchers asked a volunteer sample of people to keep a daily record of desirable and undesirable events (i.e. ‘hassles’ and ‘uplifts’) for a 12 week period. They were also asked to keep a daily record of any symptoms of illness or other discomforts during the same period.

 

Findings

The findings were as predicted: during the 3-5 day period before showing signs of colds or flu, people experienced more undesirable events and fewer desirable ones. They found that sIgA was associated with mood. When a person is happy sIgA levels are raised but when the person is unhappy or depressed, sIgA levels are lowered.

 

Conclusions

They explained their findings by arguing that production of sIgA is affected by stress caused by undesirable events, and this then makes the person more susceptible to infections.

 

Evaluation

The study has limitations in that it relies on the diary method and, for this reason the information provided by the participants may not be reliable (they may not remember reliably).

 

It also does not manipulate exposure to infection directly (it is not an experiment but relies on correlational data). A study that addressed this problem was conducted by Cohen et al. (1998), in which volunteers were actually subjected to common cold viruses. Although 80% became infected, only 40% actually developed symptoms. However, of these a significantly high number had experienced chronic stress in the month before exposure.

 

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