ارتباط روانشناختی از وضعیت عملکردی در سندرم خستگی مزمن

Background: The present study was designed to test a cognitive model of impairment in chronic fatigue syndrome (CFS) in which disability is a function of severity of fatigue and depressive symptoms, generalized somatic symptom attributions and generalized illness worry. Methods: We compared 45 CFS and 40 multiple sclerosis (MS) outpatients on measures of functional ability, fatigue severity, depressive symptoms, somatic symptom attribution and illness worry. Results: The results confirmed previous findings of lower levels of functional status and greater fatigue among CFS patients compared to a group of patients with MS. Fatigue severity was found to be a significant predictor of physical functioning but not of psychosocial functioning in both groups. In CFS, when level of fatigue was controlled, making more somatic attributions was associated with worse physical functioning, and both illness worry and depressive symptoms were associated with worse psychosocial functioning. Conclusions: Our findings support the role of depression and illness cognitions in disability in CFS sufferers. Different cognitive factors account for physical and psychosocial disability in CFS and MS. The SF-36 may be sensitive to symptom attributions, suggesting caution in its interpretation when used with patients with ill-defined medical conditions.

The level of functional impairment of patients reporting chronic fatigue syndrome (CFS) is comparable or worse than that of patients with a variety of chronic medical conditions [1] and [2]. According to the model proposed by Wessely and Sharpe [3], CFS patients' beliefs regarding their symptoms may lead to avoidance behaviors and activity restriction, which, in turn, lead to physical deconditioning, more symptoms and greater disability. The model does not preclude the possibility that CFS symptoms may initially be caused by viral infection or immune dysfunction but addresses factors that may lead to chronicity and disability. The importance of cognitive factors in maintaining inactivity and perpetuating the symptoms of CFS is supported by a randomized controlled trial showing that patients receiving cognitive behavioral therapy in addition to medical care did significantly better after the sessions, and increasingly better at a 6-month follow-up, than did those receiving medical care alone [4] and [5]. The present study was designed to test aspects of a more general cognitive model of impairment in CFS. It suggests that the disability associated with conditions such as CFS is not only a function of severity of fatigue but also of generalized illness worry, pathological symptom attributions and depressed mood, which contribute to symptom amplification, help-seeking and avoidance of activity [6] and [7]. By definition, fatigue is the principal symptom of CFS. The unpredictability of fatigue and its day-to-day fluctuation greatly affect patients' quality of life [8]. Fatigue is also at the center of debate on treatment of CFS because cognitive and behavioral factors are involved in the persistence of fatigue [9]. Prolonged bed rest and inactivity have been shown to cause physical deconditioning [10] and [11], as well as functional impairment independently of level of fatigue [12]. Not long ago, CFS patients were encouraged to rest in order to recover but, currently, CFS patients are encouraged to resume their normal activities as much as possible in order to break the vicious circle of fatigue and deconditioning [13]. Between 24% and 80% of CFS patients may suffer from concurrent depression [14] and [15], but, because of the similarity in somatic symptoms between CFS and depression, the precise status of comorbid depression is controversial [16] and [17]. Whether depression is considered as a primary, secondary or comorbid psychiatric disorder, it is clear that frustration at not being able to undertake normal activities can lead to depressive symptoms. In turn, by encouraging inactivity, depression may perpetuate CFS and disability [3]. Excessive attention to the body and worry about symptoms may contribute to CFS patients' high levels of symptom reporting, distress and disability [18]. CFS patients have been shown to report significantly greater perceived vulnerability to illness than a control group of MS patients [19]. Moreover, illness worry was a significant predictor of physical disability in a group of patients with fibromyalgia, a syndrome characterized mainly by pain and fatigue, but not in a group of rheumatoid arthritis patients [20]. Attributing fatigue and other symptoms to an external cause may maintain or exacerbate inactivity in CFS patients, therefore, increasing their disability. According to Chalder et al. [21], attributing fatigue to a social cause, such as “excessive work pressures,” seems to protect against psychosocial distress by relieving the person of responsibility for the illness, but at the same time it promotes inactivity leading to more disability. The tendency to attribute common somatic symptoms to physical illness was shown to be associated with chronicity of fatigue in primary care [9]. Physical illness attributions along with the presence of an emotional disorder were found to be associated with disability in two studies of patients with fatigue [22] and [23]. A prospective study of 618 subjects attending 42 different general practitioners' clinics in London and who presented with a viral illness found that postviral fatigue (persistent fatigue at 6-month follow-up) was predicted by a somatizing attributional style, being given a less definite diagnosis of viral infection by a general practitioner and receiving a sick certificate [24]. The aim of the present study was to further explore the importance of psychological and cognitive variables in maintaining fatigue and disability in CFS. Accordingly, we examined the contribution of fatigue severity, depression, symptom attribution and illness worry to level of functioning in CFS by comparing a group of patients with CFS to a group of patients suffering from multiple sclerosis (MS). MS is a disabling neurological condition with a highly variable course due to central nervous system demyelination. MS is associated with varying levels of fatigue as well as sensory and motor impairment, including loss of vision, incontinence and weakness [25]. While the symptoms of MS differ substantially from CFS, it has been used as a comparison group in several previous studies [26]. Based on the model presented above, we hypothesized that the disability in CFS would be proportional to the severity of fatigue but would also be a function of levels of depressive symptoms, somatic symptom attributions and illness worry.

Overall, cognitive factors played a more significant role in physical and psychosocial functioning for CFS compared to MS. The ways that CFS patients attribute their symptoms, their generalized illness worries and their depressive symptoms may all contribute to greater disability perhaps through promoting inactivity. The disability associated with CFS is not only a function of the severity of fatigue but also of depressive symptoms, symptom attribution and generalized illness worry. Physical and psychosocial disability is explained by different psychological and cognitive factors. Physical dysfunction is more directly related to fatigue severity and somatic attributions, while psychosocial functioning is more related to depressive symptoms and illness worry. Our findings confirm the role of illness perpetuating factors such as depressive symptoms, attribution of symptoms and illness worries in CFS. This has important implications for treatment in CFS, which should focus on interventions aimed at overcoming these illness-perpetuating factors through cognitive behavioral therapy [13]. Moreover, because of the day-to-day unpredictability of CFS, patients' perception of control may mediate the relationship between fatigue and disability. A recent review on coping strategies in CFS suggested an association between coping and physical and psychological well being [15]. Maladaptive coping behaviors, such as significant reduction of activities in the face of fatigue, have been associated with cognitive deficits, both actual and perceived, in CFS sufferers, and could act as mediators between illness onset and illness maintenance. Future research should look at locus of control, along with coping behaviors, cognitive deficits and other psychological and cognitive measures, when examining disability in CFS patients.