b) Stress may cause physical illness directly (as described by the GAS model) or indirectly, because stressed individuals are more likely to smoke and drink and these habits lead to physical illness – cardiovascular disorders are one of these illnesses. Cardiovascular disorder is defined as any disorder of the heart and circulatory system. A study was conducted investigating the relationship between stress and cardiovascular disorders in 1991 – Krantz et al.
The following procedure was used to investigate this. The participants were thirty-nine patients and twelve controls; they were studied whilst performing three different tasks: an arithmetic task, a Stroop task and a task where they simulated public speaking. Each of these tasks was designed to create mild stress. The Stroop task involves asking someone to read a list of colour words (e.g. ‘RED’ or ‘YELLOW’ in conflicting colours (i.e. the word ‘RED’ was in blue font). In general the Stroop task slows reading down because of the cognitive conflict caused. Measurements were taken of the participant’s blood pressure and of the extent to which blood vessels around the heart contracted (high, medium or low ischemia [ischemia means reduced blood supply]).
From these procedures a conclusion was deduced, the findings support the idea that there is a direct link between performing a mildly stressful cognitive task and physiological activity that could damage the cardiovascular system. Although, not all of the cardiovascular patients responded in the same way, which leads us to further conclude that there are important individual differences in responsiveness.
c) Physiological psychology is about the systems that operate in our bodies, such as the action of blood, hormones, nerves and the brain. The way we think and feel has important influences on these physiological systems as is illustrated by the study of stress.
There has been much research conducted concerning the relationship between stress and illness. Much of our understanding of the nature of stress can be traced back to the work of Hans Seyle in the 1930s. From his research Seyle put forward his ‘General Adaptation Syndrome’ model, this model proposes that there is a universal response to stress, and explains the stages throughout this response. This model is characterised by three progressive stages; alarm reaction (stress response), resistance (apparent coping) and exhaustion (breakdown and the onset of other stress related illnesses). The GAS model proposed that stress leads to illness because the body’s resources (e.g. glucose reserves) become depleted under extreme stress.
Although this study has it’s criticisms, findings from other research has too supported the notion that stress is related to illness. Krantz et al. (1991) is one of such studies, he conducted a study to investigate the possible link between stress and cardiovascular disorders. Patients with cardiovascular disorders (along with controls) were observed whilst carrying out numerous tasks that were designed to cause mild stress. From measurements of their blood pressure, and the extent to which blood vessels around the heart contracted, a number of conclusions were deduced. The findings of this study support the idea that there is a direct link between performing a mildly stressful cognitive task and physiological activity that could damage the cardiovascular system. However, not all patients responded in the same way, which leads us to conclude that there are important individual differences in responsiveness.
Aside from the ethical issues surrounding this study, the validity of the conclusions can also be questioned – the fact that measurements of blood pressure and ischemia were not taken before the tasks were carried out means that we cannot be sure that the ‘effects’ of the tasks were actually from the task at all, in fact the patients may have been the same even when resting. There have also been additional studies that agree with the conclusions of Krantz et al. These studies were conducted by Williams (cardiovascular disorder and stress) and Russek and Zohman (cardiovascular disorder and work-related stress).
It is generally thought that stress may not only affect the heart, but also the immune system – Kiecolt-Glaser et al. (1995) carried out a study into this idea. A matched participants design was used and a volunteer sample. Volunteers were split into 2 groups, the experimental group and the control group, so that necessary comparisons could be made between them. By using a ‘punch biopsy’ and assessing the levels of cytokines the immune system of individuals could be measured. The findings of the study also support the view that chronic stress depresses the functioning of the immune system, and that stress lowers the immune response directly. The only significant flaw in this study was the fact that a biased sample was used, it is likely that it was very difficult to match participants accurately. Further studies by Brady (1958), Cohen et al. (1993), Riley (1981) and Kiecolt-Glaser (1984) support these findings.
However, a study carried out by Evans et al. (1994) found quite contrasting findings. By studying the activity if one particular antibody (sigA), they put forward the theory that stress appears to have 2 effects on the immune system; up-regulation for very short term acute stress and down-regulation for chronic stress, this fits with the SAM/HPA distinction and the essence of the GAS model. It is also important to take into consideration the fact that stress levels, and the body’s response to stress varies from individual to individual, and as a result individual differences should be taken into consideration when studying the correlation between stress and illness.
We see and experience the effects of stress everyday, in many ways. It is almost certain that stress and illness are related, a certain amount of stress is adaptive and helps us in coping with everyday life, however, once past this adaptive level the risks and problems caused by stress escalate fairly rapidly (as is indicated by the studies I have mentioned). It is difficult to avoid stress, but it is a good idea to do as much as you can to reduce high levels of stress and anxiety throughout everyday life. In my opinion, physiological research has supported the idea that stress is related to illness to quite a big extent, out of all the studies I have looked at there is only one which opposes this idea. Although, exactly how stress causes illness is still not precisely known, the GAS model proposes that resources become depleted so that the body can no longer fight infections. However, more recent research has shown that many ‘resources’ do not become depleted even under extreme stress. The current view is that the exhaustion phase is associated with increased hormone activity, such as cortisol, and it is this rather than depletion of resources that leads to stress-related illness (Sheridan and Radmacher, 1992). There is no doubt that this research into stress, its effects and possible cures (if there are any) will continue, and in time it may be possible to reduce the effects of stress and educate people more about it.
