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Introduction

Psychological aspects play an important role at each stage of an illness, from illness onset to its progression, to the psychological consequences and longevity and thereby help us to understand CHD in terms of predicting and changing behavioural risk factors and rehabilitation of sufferers. The psychological factors are relevant to a multitude of chronic and acute illnesses like CHD, HIV and Cancer. Rather than being seen as a passive response to biomedical factors, chronic illnesses can be better understood in terms of a complex interplay of physiological and psychological processes.

What is CHD?

Coronary heart disease is caused by hardening of the arteries (atherosclerosis), which are narrowed by fatty deposits. This can result in angina (pain) or a heart attack (myocardial infarction).

The prevalence of CHD

Coronary heart disease is responsible for 33 per cent of deaths in men under 65 years of age and 28 per cent of all deaths. In middle age, the death rate is up to five times higher for men than women; however, in old age, CHD is the leading cause of death among both men and women.

Risk factors for CHD

Many risk factors for CHD have been identified. These are regarded either as (1) non-modifiable, such as educational status, social mobility, social class, age, gender, family history and race, or (2) modifiable such as smoking, behaviour, obesity, sedentary lifestyle, perceived work stress and type a behaviour, however, whether some of the latter can be changed is debatable.

The role of psychiatry in CHD

Psychiatry has a role to play in CHD, both in predicting and changing behavioural risk factors (e.g. diet, exercise) and in developing rehabilitation programmes, and preventing reinfarction (see fig 1).

THE POTENTIAL ROLE OF PSYCHIATRY IN CORONARY HEART DISEASE

The role of psychiatry in CHD will now be examined in terms of (1) predicting and changing behavioural risk factors and (2) the rehabilitation of sufferers.

Predicting and changing behavioural risk factors

1. Stress

Stress has been studied extensively as a predictor of CHD. In the 1980s Karasek developed his job demand-job control model of stress, which was further developed by Karasek and Theorell in the 1990s. The model predicts that personal control over a stressor and job stress predicts coronary heart disease and developed 'the job demand control hypothesis', within which he defines the term 'Job Strain'. According to this model, there are two aspects of job strain; job demands, which reflect conditions that affect performance, and job autonomy, which reflects the control over the speed or the nature of decisions made within the job. Karasek's job demand and control hypothesis suggests that high job demands and low job autonomy (control) predict coronary heart disease.

Recently, Karasek and colleagues developed the job control demand hypothesis to include social support. Social support is defined as either emotional support, involving trust between co-workers and social cohesion, or instrumental social support, involving the provision of extra resources and assistance. Subjects in low social support and high social support groups, and their decisional control and demands of their job were measured. The results indicated that subjects in the high social support group showed fewer symptoms of CHD than those subjects in the low social support group.

2. Diet

Diet, in particular cholesterol levels, has also been implicated in CHD. It has been suggested that 20 per cent of a population with the highest cholesterol levels are three times more likely to die of heart disease than 20 per cent with the lowest levels. Cholesterol levels may be determined by the amount of saturated fat consumed (derived mainly from animal fats). Cholesterol reduction can be achieved through a reduction in total fats and saturated fats, an increase in polyunsaturated fats and an increase in dietary fiber.

3. Smoking

One out of four deaths from CHD is thought to be caused by smoking. Smoking more than 20 cigarettes a day increases the risk of CHD in middle age three times. In addition, stopping smoking can have the risk of another heart attack in those who have already had one.

4. High blood pressure

High blood pressure is also a risk factor for CHD – the higher the blood pressure the greater the risk. It has been suggested that a 10mmHg decrease in a population's average blood pressure could reduce the mortality attributable to heart disease by 30 percent. Blood pressure appears to be related to a multitude of factors such as genetics, obesity, alcohol intake and salt consumption.

5. Type A behaviour

Type A behaviour is probably the most extensively studied risk factor for coronary heart disease. Friedman and Rosenman (1959) initially defined Type A behaviour in terms of excessive competitiveness, impatience, hostility and vigorous speech. Type A1 was defined as vigour, energy, alertness, confidence, loud speaking, rapid speaking, tense clipped speech, impatience, hostility, interrupting, frequent use of the word `never' and frequent use of the word 'absolutely'. Type A2 was defined as being similar to Type A1, but not as extreme, and Type B was regarded as being relaxed, showing no interruptions and being much quieter (Rosenman 1978).

Rehabilitation programs includes counselling and health education for patients with cardiovascular disease

The Jenkins activity survey was developed in 1971 to further define Type A behaviour. Johnston et al. (1987) used the Bortner's (1969) questionnaire to predict heart attacks in 5936 men aged 40-59 years randomly selected from GP lists. All the subjects were examined at the start of the study for the presence of heart disease and completed the Bortner questionnaire. They were than followed up for morbidity and mortality from heart attack and for sudden cardiac death for an average of 6.2 years. The results showed that non-manual workers had higher Type A scores than manual workers and that Type A score decreases with age.