تفسیر علائم در سندرم خستگی مزمن

Chronic fatigue syndrome (CFS) is an illness characterised by fatigue and other symptoms. Both psychological and biological aetiological factors have been proposed, but the disorder is of uncertain origin. The aetiology of the symptoms is therefore ambiguous. It has been suggested (a) that patients with CFS tend to interpret their symptoms as indicating physical illness and (b) they tend not to interpret these symptoms in terms of negative emotion. In order to test these hypotheses we developed a self-report questionnaire to assess the interpretation of symptoms in patients with CFS. It was administered to patients with CFS, patients with depression, patients with multiple sclerosis (MS), and normal controls. Preliminary results suggest that the measure has acceptable psychometric properties. Patients with CFS were more likely than either depressed patients or normal controls to interpret symptoms (characteristic of CFS) in terms of physical illness, but did not differ in this from the MS patients. When compared with all three other groups (including the MS patients), the patients with CFS were least likely to interpret symptoms in terms of negative emotional states. The theoretical and clinical implications of the findings are discussed.

Chronic fatigue syndrome (CFS) is a condition in which the central complaint is medically unexplained fatigue of at least 6 months' duration (Fukuda et al., 1994). The aetiology is controversial although both biological and psychological factors have been suggested (Wessely, Hotopf, & Sharpe, 1998). Despite a lack of consensus among medical scientists, and although some patients believe “stress” contributes to their illness, most patients believe that their symptoms are primarily caused by physical disease (Clements, Sharpe, Borrill, & Hawton, 1997). Moreover, despite the fact that psychological factors such as anxiety and depression play a role in the aetiology of CFS (Wessely et al., 1998), patients often actively resist this suggestion (Surawy, Hackmann, Hawton, & Sharpe, 1995). The tendency to interpret symptoms in terms of physical disease rather than emotion is potentially of clinical importance as it has been shown to predict a poor outcome (Joyce, Hotopf, & Wessely, 1997). Two measures that have been used to look at symptom interpretation are the Somatic Interpretation Questionnaire (SIQ; Robbins & Kirmayer, 1991) and the Illness Perception Questionnaire (IPQ; Moss-Morris, Petrie, & Weinman, 1996). However, the SIQ includes only somatic symptoms and not those of mental fatigue and fatigibility, while the IPQ focuses (among other things) on attributions about illness as a whole, not its symptoms. Neither were designed specifically for CFS patients. A cognitive model of CFS, based on systematic observation of over 100 patients meeting criteria for CFS, has been proposed (Sharpe et al., 1991) and recently elaborated by Surawy et al. (1995). The model as a whole attempts to explain how early experiences lead to the formation of assumptions that, combined with certain life stressors, may precipitate CFS in predisposed individuals. The model then attempts to explain how cognitive, behavioural, biological, and social factors interact, in a vicious circle, to perpetuate or maintain the illness. According to this model, the interpretation of symptoms predominantly in terms of physical illness, and not in terms of negative emotional states, plays a particularly important role in the maintenance of the disorder. Differences in this tendency between CFS patients and other groups is hypothesised to be a result of the formers' underlying assumptions and early experiences (Surawy et al., 1995) in which expression of negative emotion produced an unsympathetic response. Our clinical experience suggests that this bias is particularly evident for ambiguous symptoms. That is, for symptoms for which several possible alternative explanations, including a psychological one, are plausible. For example, a CFS patient who was having difficulty concentrating, following an argument with her partner, attributed the difficulty to a physical illness (a virus infection), rather than to psychological factors (feeling tense as a result of the argument). Given the uncertain origin of these symptoms, and potential implications of patients' interpretations for treatment and outcome, we designed a study to investigate how patients interpreted their symptoms. In other disorders, experimental cognitive psychologists have investigated patients' information processing in some detail, particularly in anxiety (e.g. Eysenck, Mogg, May, Richards, & Mathews, 1991). Biases observed have been explained in terms of a combination of cognitive structures and beliefs, together with the use of judgemental heuristics, or information processing shortcuts (Butler & Mathews, 1983). However, to date, little empirical research has been carried out to assess information processing in CFS. The current study was therefore designed to investigate Surawy and colleagues' recent model in more detail. In particular, it investigated the tendency to interpret symptoms in terms of physical illness and away from negative emotional states. The following predictions were made about the patients with CFS, compared to patients with depression, patients with a chronic physical illness (multiple sclerosis: MS) and normal controls: 1. That patients with CFS, compared to patients with depression and normal controls, will show a tendency to interpret symptoms in terms of physical illness; a tendency that is likely to be similar to that found in patients with a chronic illness that has a known physical cause1. 2. That patients with CFS, compared to participants in all three other groups (including those with a chronic physical disease), will be less likely to interpret symptoms in terms of a negative emotional state. To test these predictions a questionnaire, based on one initially devised by Butler and Mathews (1983) to assess information processing in anxiety, was designed and administered to four groups of participants.