The term ‘stress’ is usually used to describe situations, in which individuals are faced with demands that exceed their immediate ability to cope. Stressful situations are typically those that are novel, unpredictable, and uncontrollable as well as those involving change or negative events such as a loss. These situations can give rise to adverse psychological and physiological changes which, in turn, may result in disease.⁽⁶⁾

Stress may have indirect effects on health by increasing levels of risk behaviour (e.g. smoking, alcohol consumption), or may have direct effects on specific physiological mechanisms (e.g. increase in blood pressure) as well as affecting the individual’s resistance to disease through suppression of the immune system, or by exacerbating or triggering a disease process in an already vulnerable individual.

A range of behavioural and emotional responses are shown by individuals as they attempt to cope with stressful situations and these are accompanied by autonomic, neuroendocrine, and immunological changes. During stressful episodes, releasing factors from the brain cause the pituitary to release ACTH which gives rise to the release of corticosteroids from the cortex of the adrenal glands. In addition to producing a number of well-known changes associated with the mobilization of both short- and longer-term physical resources (e.g. release of adrenaline (epinephrine) or noradrenaline (norepinephrine), release of glucose, activation of endorphins/ encephalins, etc.), these steroids can also have effects on the immune system.⁽⁷⁾

The effects of stress on immunity have sparked the development of the new multi-disciplinary field of psychoneuroimmunology which focuses on the links between psychological, endocrine, and immunological processes (see Chapter 2.3.10). A large amount of work in this area has concentrated on the links between stress and immune function, but less work has focused on impaired immunity and the later development of disease. Acute stressors, such as examinations, or more chronic stressors, such as caring for
a dependent elderly relative, have been shown to lead to deleterious immunological changes. Work has also associated stress with a greater susceptibility to viral infection⁽⁸⁾ as well as longer healing times for experimental puncture wounds⁽⁹⁾ and wounds from surgical operations.⁽¹⁰⁾ A recent meta-analysis of studies of stress and immunity shows substantial evidence for a relationship between stress and impaired immune system effectiveness, particularly for chronic uncontrollable sources of stress.⁽⁷⁾

Although there is no consistent empirical support for the older idea that different diseases are linked with specific personality types, there is evidence from different, more credible sources that personality factors can influence health and play a role in determining illness in other ways.⁽¹¹⁾

Probably the best known work in this area concerns the link between the so-called ‘type A’ personality and coronary heart disease. The type A personality was originally characterized by competitiveness, time urgency, hostility, and related behavioural factors, which were associated with a significantly increased risk of coronary heart disease (CHD). However, it is now thought that only certain components (e.g. anger and hostility) of the original type A formulation are ‘pathogenic’.⁽¹²⁾

Type A individuals show a greater physiological reactivity (e.g. in blood pressure and heart rate) to environmental demands and may even generate more demands by their style of behaviour. The more frequent elevations in blood pressure and higher levels of hormonal change, characteristic of this behavioural style, may eventually cause adverse physical changes to the heart and blood vessels. Also, type A individuals are more likely to engage in unhealthy behaviours since they drink more alcohol than type B individuals and, if they smoke, they inhale their cigarette smoke for a longer time.

Type A behaviour is probably the most extensively investigated personality factor in current health psychology research, and there have been interventions developed to change the behaviour pattern, with positive health outcomes.⁽¹³⁾ More recently the concept of the type D personality has been described as another major psychological risk factor for CHD. Type D refers to the tendency to experience negative emotional states and to inhibit the expression of these emotions in social settings. Type D patients with CHD have been found to have a significantly higher risk of further cardiac morbidity in the short- and longer-term.⁽¹⁴⁾

More generally, patterns of positive or negative emotional responses, associated with personality, can influence various aspects of health.^(11,15) Individuals who are high in negative affect (i.e. experience more negative emotions, particularly anxiety) do not seem to be more prone to disease, but they are more likely to notice bodily changes and symptoms and consequently seek medical help more frequently (see Wiebe and Smith⁽¹⁵⁾ for a more detailed account of negative affect and the links between personality and health).

Another aspect of personality which has been shown to be health protective is optimism, which describes a tendency towards positive expectations in life and which enables individuals to cope better with stressors and engage in healthier lifestyles. There is emerging evidence that optimistic individuals not only cope more effectively with illness and other life crises but also show better health outcomes than those with lower levels of optimism.⁽¹⁶⁾

The effects on health of behaviours such as smoking and high alcohol use are well documented.⁽¹⁾ There is overwhelming evidence that smokers not only are much more likely to die from lung cancer and other cancers but also have much higher rates of cardiovascular disease and chronic respiratory disorders, particularly emphysema and chronic bronchitis. Moreover, the disease risk is dose related in that higher levels of smoking are more strongly associated with all these diseases. With sustained high levels of alcohol use a different but equally unpleasant spectrum of health problems can be seen. Drinking is a major cause of accidents particularly motoring accidents and can cause liver damage as well as having detrimental effects on brain functioning.⁽¹⁾

For health psychologists, the key questions about health-risk behaviours concern their origin, their maintenance, and their prevention or treatment. There are diverse determinants of these behaviours since they may start as ways of coping with stress, in response to peer pressure, for pleasure or for a number of other reasons. Similarly, they will be maintained by a variety of psychological, social, and biological factors.

There are many other risky behaviours that cannot be discussed in detail in an overview; these include drug abuse, poor diet, and accidents, and the health effects of all these are also well documented.⁽¹⁾ Although health psychology has an important role to play in describing, explaining, and intervening in all risk behaviours, these problems should not be conceptualized exclusively in individual behavioural terms since they often reflect adverse social circumstances or particular cultural contexts.⁽¹⁷⁾

The same caveats about the influence of social and cultural factors must also be applied to the understanding of health-protective or health-enhancing behaviours. Prospective cohort studies have confirmed that various daily behaviours (e.g. patterns of eating, sleeping, and exercise) can have significant long-term effects on health.⁽¹⁸⁾ For example, there is now a growing body of evidence to indicate that regular exercise has a beneficial effect on both physical and psychological health.⁽¹⁹⁾ Exercise can reduce the incidence of physical health problems in elderly people and facilitate recovery from heart attack. However, there can be significant problems in ensuring that exercise and other health-promoting activities are adhered to. Interventions need to be planned carefully, because it has been shown that it is usually very difficult to make and maintain changes in health-related behaviour. Information provision is rarely sufficient to promote behaviour change since it is also necessary to elicit and modify beliefs (see below) as well as influencing social networks in order to ensure success.

Even though health psychologists acknowledge the importance of situational, dispositional, and socio-cultural factors as determinants of health-related behaviour, most current research has a primary focus on the role of beliefs in explaining variance in healthrelated behaviour. The most widely used explanatory approaches have been described generically as ‘social cognition models’ (see Conner and Norman⁽²⁾ for an excellent overview of these models). These models are based on the premise that, when a person is faced with having to make a decision about a particular health behaviour (e.g. attend for a screening test; wear a seat belt, etc.), their decisionmaking and behaviour can be best understood in terms of their perceptions or beliefs about the health issue and the behaviour in
question. The best known models here are the Health Belief Model, Theory of Reasoned Action/Theory of Planned Behaviour, and Protection-Motivation Theory. Broadly these models locate the strength of certain beliefs or evaluations of the health threat (e.g. ‘is it serious? Is it likely to affect me?’) and/or the associated health behaviour (‘Is it an acceptable or worthwhile thing for me to do?’) as the key determinants of an individual’s motivation or intention to carry out the behaviour. More recent models incorporate other beliefs, such as self-efficacy, which reflect the individual’s belief about their ability to implement or carry out the health-related behaviour.

For habitual and addictive health-related behaviours (e.g. dietary behaviour; substance abuse) there have also been attempts to develop stage-based models, such as the Precaution Adoption model and the Transtheoretical model⁽²⁾ as ways of describing the stages which people may go through in evaluating the health issue through to thinking about, planning, and maintaining behaviour change. Although these stage models provide a framework for identifying the patient’s state of readiness for a health behaviour change intervention as well as an immediate target for an intervention, the evidence for them is weak and there are now a number of serious critiques of their validity and applicability.⁽²⁰⁾

Understanding how symptoms are perceived is critical to explaining variation in illness behaviour. Psychological factors play an important role in the appraisal of symptoms. There is considerable evidence that bodily symptoms and functions are not perceived with a high degree of accuracy and individuals vary widely in what symptoms are noticed and whether medical help is sought for symptoms.⁽²¹⁾

The probability that individuals will attend to somatic information will depend on the competition for attention from other sources of available stimuli. When the environment is lacking in stimulation individuals tend to pay more attention to bodily symptoms. Conversely, when an individual’s attention is drawn to the external environment, bodily symptoms are less likely to be noticed. This finding has wide day-to-day applications ranging from why people cough in the boring parts of movies and lectures to explaining demographic differences in symptoms reports, such as increased symptom reporting among the socially isolated and the unemployed. It also has clinical applications in chronic pain and other chronic medical conditions where patients’ isolation may exacerbate the condition by increasing preoccupation with symptoms.

Cognitive schemas can also strongly influence the reporting of physical symptoms by guiding the way individuals pay attention to their body. Schemas determine the organization of incoming information and guide health directed behaviour. There is a strong tendency for individuals to search for information that is consistent with existing schemas and disregard information that does not fit. Individuals also attach more importance to symptoms consistent with a current cognitive schema than other symptoms. Schemas may develop through personal experience with the condition or by having come across the illness through family, friends, or in the media. Illness schemas can vary from vague ideas about the types of symptoms that represent an illness to more elaborate and detailed conceptions of individual illnesses. Medical students’ disease, where students studying a particular illness notice they also have the symptoms of the condition, and episodes of mass psychogenic illness are more dramatic demonstrations of this phenomenon, but the process is seen on a more subtle level with response to placebos (see below). Here, following treatment, a new cognitive schema may shift attention towards symptoms that indicate recovery rather than those of the illness.

There is growing research to suggest that patients’ interpretation of their symptoms can influence help-seeking behaviour.⁽²²⁾ One medical condition where delay can have serious consequences is myocardial infarction, as early arrival at hospital is strongly associated with improved chances of survival. There is a large variation in how long patients delay before seeking help, and a strong predictor of early arrival at hospital is the belief that the symptoms are a heart attack.⁽²³⁾ Heart attacks are generally seen as sudden and dramatic events that involve severe chest pain and collapse. In the case of myocardial infarction patients, the mismatch between these expectations and the symptoms experienced gives rise to patient delay.

Research investigating the stages of patient delay for medical conditions has generally found three main stages prior to entering treatment, with each stage influenced by a different set of factors and decisional processes. The first interval is generally referred to as appraisal delay, which is the time period from when the individual first detects symptoms to when an illness is inferred. The main influences on this period are factors related to interpretation of symptoms. The second interval is called illness delay—the period from the time the individual decides he or she is ill until the decision is made to seek medical help. The final period called utilization delay is the time until the individual enters hospital or has contact with medical personnel. This first period of appraisal delay has been generally found to cause the largest contribution to overall delay.⁽²⁴⁾