تجزیه و تحلیل تجربی از نقش جبران طرحواره در بی اشتهایی عصبی

It has been suggested that the relatively poor effectiveness of treatments for anorexia nervosa is due to a poor conceptualisation of the disorder. One hypothesis is that current models are mistakenly targeting superficial, instead of deeper level, cognitions and cognitive processes. A schema-based cognitive–behavioural model of eating disorder pathology suggests that the process of schema compensation is key to restrictive pathology—when there is the threat of experiencing negative affect, compensatory schemas are activated, reducing that affect. The current experimental study aimed to provide support for such a process. Eating-disordered and control women completed a computer-based task, measuring the compensation process in terms of speed and accuracy in response to subliminal threat cues. The results did not fully support the hypothesis, suggesting that the model and methodology need some amendment. Improvements to the methodology are discussed.

Despite relative success in establishing effective treatment for bulimia nervosa Agras et al., 2000 and Fairburn et al., 1995, empirically validated treatments for anorexia nervosa are conspicuous by their absence. Clinicians and researchers alike are still seeking to understand anorexia nervosa fully Fairburn et al., 1999 and Waller & Kennerley, 2003. Until recently, cognitive–behavioural models of anorexia nervosa (e.g., Garner & Bemis, 1982 and Garner & Garfinkel, 1997) have hypothesised that anorexic behaviours are precipitated and maintained by a series of maladaptive thoughts and dysfunctional assumptions regarding body shape and weight. It has been suggested that these models are mistakenly targeting superficial cognitions, instead of more clinically relevant issues of control, body image disturbance, and schema-level cognitions (e.g., Cooper, 1997 and Fairburn et al., 1999). A recent schema-based model of the eating disorders (Waller, submitted for publication) suggests a central role for compensatory schemas and processes in anorexia nervosa. This model is based in the evidence (e.g., Cooper & Hunt, 1998, Cooper & Turner, 2000 and Leung et al., 1999) that there are similar dysfunctional core beliefs across different eating disorders, and that those beliefs are developed from what are often similar patterns of early experiences. However, it is hypothesised that restrictive and bulimic pathologies differ in the schema processes involved. Restriction is characterised by the use of cognitive and behavioural strategies to avoid negative emotion being triggered (primary avoidance of affect). Bulimia is characterised by the use of such strategies once the emotion has already been triggered (secondary avoidance of affect). In anorexia, in a situation where there is the threat of experiencing negative affect, compensatory schemas (including beliefs and behaviours) are activated. These compensatory schemas typically include unrelenting standards (e.g., striving for perfection at school or work, to avoid the risk of depression due to seeing oneself as a failure), emotional inhibition (e.g., avoidance of the experience or expression of emotion, for fear of demonstrating anger at another person), and subjugation (e.g., focusing on satisfying the wishes and needs of others to avoid the loneliness that might follow from being abandoned by them). There is some preliminary evidence for this model of restrictive pathology from studies employing questionnaire methodology. Luck, Waller, Meyer, & Lacey (submitted for publication) have shown that anorexic patients show greater levels of schema compensation (primary avoidance of affect) than bulimia nervosa patients or nonclinical controls do. However, there is no causal evidence for this model to date, and it will be important to test it within experimental paradigms. Given the model of restrictive behaviour, it can be hypothesised that the activation of negative schema-level beliefs among anorexics will trigger compensatory cognitions and a range of different compensatory behaviours (i.e., the observable aspect of the compensatory schemas and processes). As described above, a number of potential compensatory schemas may be activated (depending on developmental experience and the nature of the triggering core belief), but the characteristic frequently observed in anorexia nervosa is perfectionist behaviour (e.g., Shafran & Mansell, 2001). Given the prevalence of this behaviour among restrictive cases (e.g., Slade, 1982), it is predicted that individuals with anorexia nervosa will respond to negative or threatening events by engaging in a greater level of perfectionist behaviours. The aim of this study was to demonstrate an increase in perfectionism following the presentation of a negative stimulus, thus providing support for the role of compensatory schemas and processes within the proposed model. To test the model fully, a behavioural manifestation of perfectionism was used, rather than self-report. This involved a computer-based search task (adapted from Slade, Newton, Butler, & Murphy, 1991), where oversearching for an absent cue was used as the index of perfectionism (see below). To reduce the behavioural impact of demand characteristics, the trigger stimulus used was a subliminal threat cue. The subliminal presentation of threat cues has been shown to have behavioural effects. For example, such cues trigger increased eating in individuals with bulimic attitudes (Patton, 1992), particularly, where the threats are ego, rather than physical, threat cues, food-related cues, or positive affective cues Meyer & Waller, 1999 and Waller & Mijatovich, 1998. It was predicted that anorexic participants would take longer to respond (i.e., increased oversearching) when presented with a subliminal negative affect cue. Given the findings of previous experimental studies with nonclinical women with eating concerns Meyer & Waller, 1999, Meyer & Waller, 2000 and Patton, 1992, it was hypothesised that this effect would be strongest for the cue word representing abandonment fears (i.e., lonely).