Empirical support for the main components of the SEMP
It has been shown that the application of information processing approaches to the study of chronic pain has proven influential by avoiding the limitations associated with classical selfreport measures. Further, it has been shown that conditions such as chronic pain or depression may be distinguished from one another, on the basis of these associated cognitive biases. Most importantly, observations of dysfunctional processing associated with chronic pain hold important implications for the development of new treatment modalities. The SEMP model has been developed through close scrutiny of the existing literature and it provides many testable hypotheses (Pincus and Morley, 2001): (1) processing priorities depend on the salience of information to the content of schemas; (2) all pain patients are proposed to preferentially process pain information; (3) self-referential material is also preferentially processed, especially when congruent with the self-schema; (4) therefore self-referential health-related information would be preferentially recalled, particularly by depressed chronic pain patients, as illness information is enmeshed, and therefore congruent with the self schema; (5) however, enmeshment does not necessarily indicate self-denigratory beliefs, so depressed pain patients would not preferentially recall typical depression-related information, in contrast to clinically depressed patients without chronic pain. Although the SEMP model has been proposed recently, there are already several existing studies, which have directly tested predictions from the SEMP (Davies 2003; Gray 2006; Harris et al. 2003; Morley et al. 2005; Pincus et al. 2007; Read and Pincus 2004; Sutherland and Morley 2008).
As can be seen from the abovementioned research, self-pain enmeshment can be operationalized and measured in different ways. A novel approach for studying self-pain enmeshment and depressive thinking in chronic pain patients has been proposed by Pincus et al. (2007). Beside questionnaires and information-processing methodologies, a sentence completion method has been developed to overcome the limitations of endorsement methodology and elicit idiographic information by describing patients’ individual perspectives (Barton and Morley 1999; Barton et al. 2005; Rusu et al. 2009). Briefly, the Sentence Completion Test for Chronic Pain (SCP; Rusu 2008) has been illustrated as a promising approach, which might help to clarify the relationship between pain and depression/distress, contribute to the identification of underlying schemas in depressed pain patients, and might also be of use for case formulation. A first study using a preliminary version of the SCP showed that depressed pain patients generated more negative health- related completions (particularly directed towards the future), than non-depressed pain patients and control participants (Pincus et al. 2007). Non-depressed pain patients focused on health as well, but not necessarily in a negative way. Moreover, the predominance of danger-related thoughts in anxiety patients (Beck et al. 1974; Rachman et al. 1988), contrasts with the themes of loss and self-devaluation in depressive negative automatic thoughts (e.g. Beck et al. 1979), and is the basis of the content-specificity hypothesis (Beck 1987; Beck et al. 1987). In pain, studies have demonstrated that the type of depression experienced by chronic pain patients differs qualitatively from patients with clinical depression by a tendency for health-related negative processing, without the component of self-denigration, shame, and guilt often found in clinical depression (Pincus and Morley 2001; Pincus et al. 1995, 2007). While traditional measures of depressive thinking are based on Beck’s (1970) cognitive triad of self, world and future and contain lists of negative thoughts that occur automatically during depressed mood (Beck et al. 1961, 1987; Hamilton 1967; Hollon and Kendall 1980), it has been argued that this kind of measure will approximate a patient’s thoughts rather than capture them exactly (Barton and Morley 1999).
Consistent with the SEMP model, Rusu and colleagues (Rusu 2008; Rusu et al. 2008, 2009, in prep.) manipulated self-reference and future reference as a condition during encoding in a recall task and generation of idiographic content in a sentence completion task in a series of experiments, and found that recall biases and cognitive content in pain patients was specific to pain- and illness-related descriptors and themes. More specifically, in depressed pain patients the negative health-related cognitive biases were firmly connected with patients’ view of themselves in the future. This might indicate that the experience of chronic pain combined with depressed or distressed mood might lead to a generalization and amplification of cognitive biases, which also extends to the future (see Figure 16.2 for the hypothesized enmeshment for different groups). As both pain groups (whether depressed or not) were involved with pain experiences, one possible explanation for the findings of the depressed pain group would be that the implications of pain go beyond the pain itself, into the domain of health and illness, as presumed by the SEMP model. This explanation would be in line with the results of Pincus et al. (1995), who reported that depressed pain patients showed a marked bias towards illness-related words, which was stronger than for pain-related words. At present it is not known which factors are causing cognitive vulnerabilities, or which processes might lead to the generalization and amplification of cognitive biases, but it is conceivable that factors such as pain catastrophizing, hypervigilance and anxiety sensitivity (Van Damme et al. 2004b), in addition to predisposing factors, might play a crucial role in the development of distress and potentially also the maintenance of chronic pain. There is
Fig. 16.2 Hypothesized enmeshment for different groups (Rusu 2008).
evidence that hypervigilance for pain is associated with a narrowing of the attentional field and a difficulty in disengaging attention from pain and shifting toward other demands in the environment (Van Damme et al. 2002). This effect was more pronounced in persons with high catastrophic thinking. Further research is needed to clarify issues of risk and vulnerability by prospective designs.
The above mentioned findings suggest that the concept of enmeshment as captured in the current measures may provide an alternative approach to explaining distress/depression in chronic pain. Pincus and Morley (2001) note that enmeshment is not a bias in its own right but a structural feature relating the self to pain experience and offered no independent way of assessing the degree of enmeshment, which was essentially a post-hoc explanation for the observed data. Whether high levels of enmeshment represent a risk factor for depression or conversely whether low levels of enmeshment act to buffer the individual from depression cannot be distinguished by the present data. However, it should be recognized that a definitive opinion on this must await fuller explication of the concept of enmeshment and prospectively designed tests of the competing theories. Further developments using other methods, e.g. the Implicit Attitude Test (Greenwald et al. 1998) might also be considered. Additionally, the extent to which enmeshment is specific to chronic pain rather than a general characteristic of other chronic health conditions is unknown. It is conceivable that chronic pain is a particularly good model for testing the concept of enmeshment because of the extraordinary capacity of chronic pain to interrupt and interfere with ongoing cognitive and behavioural activity (Banks and Kerns 1996; Eccleston and Crombez 1999; Morley and Eccleston 2004).