Chapter 1: Introduction and background
1.5 Theoretical models of behaviour change
Upon receiving a CD diagnosis, patients are required to undergo substantial changes in behaviour if they are to adhere to a GFD. The relationship between health behaviour and adherence to treatment has received a great deal of research attention in recent years (DiMatteo, 2004). Many interventions have been designed from behaviour change theory with the aim of improving adherence to medication in chronic conditions, however, less attention has been given to developing interventions to improve dietary adherence. In this section, I describe the six most common psychological theories on the determinants of behaviour change that are applicable for adherence to treatment (Leventhal & Cameron, 1987). It is possible that these models could be used in the development of an intervention to improve long-term adherence to a GFD. The development of an intervention to change behaviour requires knowledge of the concepts (or mediators of change) that need to be targeted (Sirur et al., 2009).
Health belief model (HBM)
The health belief model (HBM), which was developed by Rosenstock, Strecher and Becker, explains behaviour change as the result of a set of beliefs about a situation (Rosenstock et al., 1988). In this model, behaviour change is based on a balance between the barriers to and the benefits of a particular behaviour (e.g. adherence) (Blackwell, 1992). According to this
model, there are four key beliefs that are weighed up in a cost-benefits analysis and this determines behaviour: 1. Perceived susceptibility (e.g. what is the likelihood that poor health outcomes will result from non- adherence?); 2. Perceived severity (e.g. how severe will the consequences of non-adherence be?); 3. Perceived benefit (e.g. adherence will be good for my health); and 4. Perceived barrier (e.g. GFF is expensive, difficult to find and does not taste good). Albert Bandura introduced the concept of self- efficacy, which relates to how competent an individual feels to engage in a particular behaviour (Strecher & Rosenstock, 1997). The concept of self- efficacy was recently added to the HBM. A person with a high sense of self- efficacy is likely to be more motivated to take action than a person with low self-efficacy who would be likely to feel helpless and not in control of a given situation.
According to the HBM, a person with CD must believe that they are susceptible to negative consequences of non-adherence before they will change their behaviour and start adhering to a GFD. However, an individual’s beliefs may not be the only reason for non-adherence and factors, such as the presence or absence of symptoms and the availability of GFF may also play a role. The HBM fails to take account of the fact that some behaviour is based on habit, rather conscious decisions.
Theory of reasoned action and planned behaviour
Azjen and Fishbein recognised that attitudes and beliefs do not account for all behaviour (Sutton, 1997). According to this theory, the intention to act is the best predictor of behaviour and the intention to change behaviour is influenced by an individual’s attitudes towards the action (Sutton, 1997). The theory of planned behaviour suggests that behaviour is influenced by three factors: 1. Attitudes (beliefs about the likely outcome of behaviour); 2. Subjective norms (perceptions of other people’s expectations of them to perform the health behaviour); and 3. Perceived behavioural control (i.e. you have the resources / opportunity to engage in the behaviour). This model suggests that individuals need to believe that they are able to successfully engage in a particular behaviour (self-efficacy) before they will change their behaviour. This builds upon the idea of ‘locus of control’ theory which suggests that a person either views events as being controlled by their own actions (internal locus of control) or by other people (external locus of control).
Sainsbury & Mullan (2011)used the theory of planned behaviour to predict adherence to a GFD in CD and found this to be a good predictor of adherence. According to the theory of planned behaviour, most behaviour is rational and an individual’s intention to behave in a particular way has a greater predictive ability than health beliefs. The theory of planned behaviour, however, does not account for unconscious or irrational behaviour that may result from emotional states or psychological problems.
Despite having an internal locus of control and strong self-efficacy a patient who does not value their health may not adhere to a GFD.
Behavioural learning theory
Behavioural learning theory relates to how people learn from their experiences and the conditioning that can take place during the early years (Lovell, 2011). This model focuses on the environment and teaching the skills and strategies required in managing adherence (World Health Organization (WHO), 2003). Behavioural learning theory explains actions in relation to internal and external antecedents (thoughts and environmental cues) and the consequences of adherence behaviour (punishment or reward). Patients with CD may have unique reasons for non-adherence to a GFD which may require a patient centred approach to care. The lack of an individual approach and the emphasis on immediate reward means that behavioural learning theory may not be appropriate for understanding behaviour or designing interventions in CD.
Social-cognitive theory (SCT)
Social cognitive theory (SCT) was developed by Bandura in 1986 and it is argued that this is the most comprehensive theory of behaviour change (Bandura, 1998; Redding et al., 2000). SCT relates to the choices individuals make and components of this theory include self-efficacy, beliefs and incentives or reinforcement (Chapman-Novakofski & Karduck, 2005). In a study focusing on exercise behaviour, Wallace et al. (2000)
applied the SCT to examine the stage of exercise behaviour change in young adults. The study reported that self-efficacy played an essential role in determining exercise behaviour. It is possible, however, that the role of self- efficacy in dietary behaviour may differ to that in exercise behaviour.
Information motivation behaviour (IMB) skills theory
The information, motivation and behavioural (IMB) skills model suggests that there are three components of behaviour change (information, motivation and behaviour skills) (World Health Organization (WHO), 2003). Information and motivation are believed to activate behaviour. Information relates to the knowledge a person has about an illness and its treatment. The IMB model suggests that, although information is a prerequisite for adherence, it is not enough to change behaviour (World Health Organization (WHO) 2003). According to this model behaviour change requires motivation and a focus on developing behavioural skills. Motivation includes the attitudes towards the behaviour, perceived social support for such behaviour and the patient’s perception of how other people with the condition might behave (subjective norm). This model acknowledges the importance of having the necessary tools and strategies required for adherence. Self-efficacy is also an important aspect of this model.
Transtheoretical (stages of change) model
The Transtheoretical (Stages of Change (SOC)) Model (TTM) describes an individual’s motivational readiness to change (World Health Organization, 2003). This model incorporates some of Bandura's self-efficacy theory. According to this model, behaviour change is thought to progress through a series of five stages:
1. Precontemplation (not considering behaviour change in the next six months) (e.g. I am not seriously thinking about following a GFD). 2. Contemplation (considering changing behaviour in the next six months)
(e.g. I think I should follow a GFD).
3. Preparation (planning to change behaviour in the next 30 days) (e.g. I am planning in my diary to make the changes).
4. Action (currently changing behaviour) (e.g. I am buying GFF).
5. Maintenance (successful behaviour change for at least six months) (e.g. I have been sticking to my GFD every day).
The TTM is useful in understanding and predicting intentional behaviour change, however, Bandura argues that behaviour change is multifaceted and cannot be divided into discrete stages.
All the theoretical models of behaviour described above make a number of assumptions. For example, these models assume that people will take an active role and are able to use foresight, plan and make decisions (cognitive
processes). In addition, these models also assume that people will self- regulate their behaviour and behave in goal-orientated ways. Models of health behaviour have been used to develop interventions for a number of health conditions, however, few have been used for dietary interventions. As far as I am aware the TPB is the only model of behaviour change that has been applied in relation to adherence to a GFD in adult CD (Sainsbury & Mullan 2011). It is unclear whether any of the other models could be successfully used to explain adherence to a GFD or in the development of an intervention to improve adherence to a GFD in adult CD.