Role of Stress in Illness

Q: __Kiecolt-Glaser et al. (1995)__

__Kiecolt-Glaser et al. (1995)__ studied carers for family members with Alzheimer’s disease. These individuals were under chronic stress.

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The Role of Stress in Illness

If the reactions that make up the stress response are chronic or if they frequently exceed normal ranges, they can lead to cumulative wear and tear of the immune system and cardiovascular system.

Chronic stress

The stress response is made up of a coordinated but complex system of physiological reactions that are called upon as needed.
These reactions are beneficial at times because they prepare us to deal with potentially dangerous or threatening situations.
But health is affected when physiological reactions are sustained, which can happen in response to ongoing stress.

Cardiovascular system

The cardiovascular system is made up of the heart and blood circulation system. There is evidence that stress directly affects this system.
A major risk factor for coronary heart disease is hypertension, otherwise known as high blood pressure. Hypertension forces a person’s heart to pump harder, putting more physical strain on the heart. Hypertension can eventually lead to heart failure, heart attack or a stroke.

Cardiovascular system cont.

Elevated stress levels have been shown to increase blood pressure. There are many stressors in people’s lives that have been linked to cardiovascular problems.
- E.g. job strain, natural disasters and marital conflict.

Immune system

The immune system is made up of a variety of structures, cells, and mechanisms that protect the body from invading toxins and microorganisms. These toxins and microorganisms can harm or damage the body’s tissues and organs.
The immune system may sometimes break down and be unable to do its job. This situation is known as immunosuppression.
Prolonged activation of the stress response has been shown to cause immunosuppression. Chronic stress can lead to increased vulnerability to infection and disease.

Studies Exploring the Effect of Stress on the Immune System

Many studies have shown that chronic stress has a negative effect on the functioning of the immune system.

Animal studies

Some of the most compelling evidence for a connection between the brain and the immune system comes from studies in which researchers showed that immune responses in animals could be classically conditioned.

Ader and Cohern (1975)

Ader and Cohern (1975) paired flavoured water (the conditioned stimulus) with an immunosuppressive drug (the unconditioned stimulus), causing sickness (an unconditioned response).
Rats exposed to this pairing developed a conditioned aversion to the flavoured water. Eventually, the taste of the water itself produced immunosuppression (a conditioned response), indicating that the immune system itself had been conditioned.

Cohen et al. (1998)

Cohen et al. (1998) interviewed 276 healthy volunteers about recent stressful experiences before giving them nasal drops containing a cold virus.
When examined later, participants who reported experiencing chronic stressors for more than one month were considerably more likely to have developed colds than were participants who reported no chronic stressors.

Evaluation of stress studies

Stressors very rarely happen independently in an individual’s life. So reduced immune system functioning may be due to more than just the stress experience.
- E.g. carers of individual’s with dementia also have poor diets and get little regular sleep. These factors have direct physiological effects and are likely to contribute to a worsened immune system.

Kiecolt-Glaser et al. (1995)

Kiecolt-Glaser et al. (1995) studied carers for family members with Alzheimer’s disease. These individuals were under chronic stress.

Method and results

Kiecolt-Glaser et al. (1995) conducted an independent measures study using 13 individuals who were carers for family members with Alzheimer’s disease (and so under chronic stress) and 13 controls.
Kiecolt-Glaser et al. (1995) made a small wound on the participant’s arms and found that this took on average nine days longer to heal for the carers than the controls.
- This suggests that the immune system is worse at healing wounds when a person is under chronic stress.