Stress reactivity

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258 HEALTH PSYCHOLOGY
Interaction between the behavioural and
physiological pathways
Stress can therefore influence health and illness by changing behaviour or by directly
impacting upon an individual’s physiology. So far the behavioural and physiological
pathways have been presented as separate and discrete. However, this is very much an
oversimplification. Stress may cause changes in behaviours such as smoking and diet
which impact upon health by changing the individual’s physiology. Likewise, stress may
cause physiological changes such as raised blood pressure but this is often most apparent
in those that also exhibit particularly unhealthy behaviours (Johnston 1989). Therefore,
in reality, stress is linked to illness via a complex interaction between behavioural
and physiological factors. Further, Johnston (1989) argued that these factors are multiplicative, indicating that the more factors that are changed by stress the greater the
chance that stress will lead to illness.
INDIVIDUAL VARIABILITY IN THE STRESS–ILLNESS LINK
Not everyone who experiences stress becomes ill. To some extent this is due to the role
of variables such as coping, control, personality and social support which are described
in detail later on. However, research indicates that this variability is also due to
individual differences in stress reactivity, stress recovery, the allostatic load and stress
resistance.
Stress reactivity
Some individuals show a stronger physiological response to stress than others which
is known as their level of ‘cardiovascular reactivity’ or ‘stress reactivity’. This means
that when given the same level of stressor and regardless of their self perceived stress
some people show greater sympathetic activation than others (e.g. Vitaliano et al. 1993).
Research suggests that greater stress reactivity may make people more susceptible to
stress-related illnesses. For example, individuals with both hypertension and heart
disease have higher levels of stress reactivity (e.g. Frederickson and Matthews 1990;
Fig. 11-3 The stress–illness link: physiological moderators
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