Stress resistance

Page 259
Black blue
STRESS AND ILLNESS
259
Frederickson et al. 1991, 2000). However, these studies used a cross sectional design
which raises the problem of causality. Some research has therefore used a prospective
design. For example, in an early study Keys et al. (1971) assessed baseline blood pressure
reaction to a cold pressor test and found that higher reactivity predicted heart disease at
follow-up, 23 years later. Similarly, Boyce et al. (1995) measured baseline levels of stress
reactivity in children following a stressful task and then rated the number of family
stressors and illness rates over the subsequent 12 weeks. The results showed that stress
and illness were not linked in the children with low reactivity but that those with higher
reactivity showed more illness if they had experienced more stress. Everson and colleagues (1997) also assessed baseline stress reactivity and explored cardiac health using
echo cardiography at follow-up. The results showed that higher stress reactivity at baseline was predictive of arteriol deterioration after four years. In addition, stress reactivity
has been suggested as the physiological mechanism behind the impact of coronary prone
behaviours on the heart (Harbin 1989; Suarez et al. 1991). This doesn’t mean that
individuals who show greater responses to stress are more likely to become ill. It means
that they are more likely to become ill if subjected to stress.
Stress recovery
After reacting to stress the body then recovers and levels of sympathetic and HPA
activation return to baseline. However, some people recover more quickly than others
and some research indicates that this rate of recovery may relate to a susceptibility to
stress-related illness. This is reflected in Seyle’s (1956) notion of ‘exhaustion’ and the
general wear and tear caused by stress. Some research has focused particularly on
changes in cortisol production suggesting that slower recovery from raised cortisol
levels could be related to immune function and a susceptibility to infection and illness
(e.g. Perna and McDowell 1995).
Allostatic load
McEwan and Stellar (1993) described the concept ‘allostatic load’ to reflect the wear and
tear on the body which accumulates over time after exposure to repeated or chronic
stress. They argued that the body’s physiological systems constantly fluctuate as the
individual responds and recovers from stress, a state of allostasis, and that as time
progresses recovery is less and less complete and the body is left increasingly depleted.
Therefore if exposed to a new stressor the person is more likely to become ill if their
allostatic load is quite high.
Stress resistance
To reflect the observation that not all individuals react to stressors in the same way,
researchers developed the concept of stress resistance to emphasize how some people
remain healthy even stressors occur (e.g. Holahan and Moos 1990). Stress resistance
includes adaptive coping strategies, certain personality characteristic and social support.
These factors are dealt with in detail later on.
Page 259
Black blue