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There is a strong rationale and role for the discipline of health psychology. First, the behavioural basis for illness and mortality requires effective methods of behaviour change. Second, a holistic system of health care requires expert knowledge of the psychosocial needs of people.

In relation to point 1, all the leading causes of illness and death are behavioural. This means that many deaths are preventable if effective methods of changing behaviour and/or the environment can be found.

BOX 1.4 KEY STUDY: The Global Burden of Disease study

An important epidemiological perspective comes from measures of ‘disability’ or ‘disablement’. The Global Burden of Disease (GBD) study projected mortality and disablement over 25 years. The trends from the GBD study suggest that disablement is determined mainly by ageing, the spread of HIV, the increase in tobacco-related mortality and disablement, psychiatric and neurological conditions, and the decline in mortality from communicable, maternal, perinatal and nutritional disorders (Murray and Lopez, 1997).

The GBD study was repeated in 2010 and figures were prepared by age, sex and region for changes that had occurred between 1990 and 2010. Global figures for life expectancy show increases for all age groups (Figure 1.3).

The GBD uses the disability-adjusted life year (DALY) as a quantitative indicator of the burden of disease. It reflects the total amount of healthy life lost that is attributed to all causes, whether from premature mortality or from some degree of disablement during a period of time. The DALY is the sum of years of life lost from premature mortality plus years of life with disablement, adjusted for the severity of disablement from all causes, both physical and mental (Murray and Lopez, 1997).

Figure 1.3 Percent change in total DALYs, 1990–2010

Source: Institute for Health Metrics and Evaluation (2014), www.healthdata.org/infographic/percent-change-total-dalys-1990-2010

The data in Table 1.3 indicate that nearly 30% of the total global burden of disease is attributable to five risk factors. The largest risk factor (underweight) is associated with poverty (see Chapters 4 and 5). The remaining four risk factors are discussed in Part 2 of this book (see Chapters 8–13).

There were changes in the total DALYs attributable to different causes between 1990 and 2010, as shown in Figure 1.3. Good progress is evident in DALYs for the lower respiratory tract and diarrhoea, but a huge increase of 354% occurred in DALYs for HIV patients. Moderate but significant increases in DALYs occurred for heart disease, stroke, low back pain, depression and diabetes.

The statistics on death and disablement indicate the significant involvement of behaviour and therefore provide a strong rationale for the discipline of health psychology in all three of its key elements: theory, research and practice. If the major risk factors are to be addressed, there is a pressing need for effective programmes of environmental and behavioural change. This requires a sea change in policy. The dominant ideology that makes individuals responsible for their own health may not be the most helpful approach. The environment is a hugely important factor. In our opinion, a psychological approach in the absence of environmental change is like whistling in the wind.

Table 1.3

Health psychologists are at the ‘sharp end’ of the quest to produce health behaviour change on an industrial scale. The fact that people are highly constrained by their environment and socio-economic circumstances militates against such change. In a sense, without adaptations of the environment, this effort is disabled. There are strong constraints on the ability of health care systems to influence health outcomes at a population level because of the significant social and economic determinants that structure the health of individuals and communities. The environment must change, and by that route there can be behaviour change on a societal scale. Attempting to change behaviour without first attending to the environment is akin to ‘the tail wagging the dog’, mission impossible.

A second rationale for health psychology is growing recognition that a purely medical approach to health care is failing to meet the psychosocial needs of many patients. This has led to a search for an alternative perspective that values holistic care of patients and attempts to improve services through higher quality psychosocial care. In spite of their very high costs, health care systems are often perceived to be inefficient, ineffective and unfit for purpose. This is especially the case in the USA, where the largest per capita expenditure is producing some unimpressive outcomes.

The biomedical model has been criticized since the 1970s (Illich, 1976). While medical experts want to give modern medicine the credit for the decline of disease in the twentieth century, critics have suggested that health improvements are due mainly to better hygiene, education and reduced poverty (McKeown, 1979). In addition, there has been a growing awareness of psychological and social influences in health and illness which has been formulated as the biopsychosocial model (BPSM) (Engel, 1977). Following in the footsteps of Weiss and von Bertalanffy, Engel observed that nature is a ‘hierarchically arranged continuum with its more complex, larger units superordinate on the less complex smaller units’ (Engel, 1980: 536). He represented the hierarchy either as a vertical stack or as a nest of squares, with the simplest at the centre and the most complex on the outside (Figure 1.4). At the very beginning of this chapter, we print a quotation from Engel (1980), part of which states: ‘In no way can the methods and rules appropriate for the study and understanding of the cell as cell be applied to the study of the person as person or the family as family.’ Our review of the core construct of homeostasis in the next chapter will prove this part of Engel’s statement to be 100% false. Homeostasis is a unifying principle across the continuum of natural systems from the molecule at one end to the biosphere at the other.

Figure 1.4 Continuum of nature from the simplest unit to the most complex

Adapted from Engel (1980)

The vertical stack was sub-divided into two stacks, the first starting with subatomic particles and ending with the individual person, the second starting with the person and finishing with the biosphere. The first is an organismic hierarchy, the second a social hierarchy. The constructs of a biological/organismic and a social universe are both integral to the study of health psychology. There has been a lot of discussion in health psychology about the adoption of the BPSM. However, the evidence of this adoption in medical education is meagre. A majority of US physicians reported not receiving effective training regarding the role of the BPSM, and thus have feelings of low self-efficacy in addressing and managing biopsychosocial issues (Moser and Stagnaro-Green, 2009). Some reference to the BPSM occurs in the nursing research literature on patient-centred care, but the specific influence of the BPSM on nursing is not significant (e.g., Mead and Bower, 2002; Kitson et al., 2013). The paradigm shift that Engel proposed for health care is yet to happen.

One crucial tool in the development of the BPSM and of health psychology as a discipline is the need for measurement of psychological variables.