Illness perceptions and mood in chronic fatigue syndrome
Introduction
The importance of illness representations and cognitions in adjustment to long term conditions, such as chronic fatigue syndrome (CFS) has been recently recognised [1]. Petrie et al. [2] have found that catastrophic thinking was related to increased disability and fatigue in CFS patients, even controlling for the number of symptoms, psychological disturbance and help-seeking behaviour. Ray et al. [3] found that aspects of illness beliefs could predict progression of CFS with a stronger belief in perceived controllability of the condition at initial assessment being linked to better outcome.
Mood may also have an effect on adjustment in CFS. Ray et al. [4] has found that emotional distress correlates with factors that are predictive of illness severity (i.e., cognitive difficulty). This suggests disturbed mood can indirectly affect CFS by exacerbating symptoms, thus, amplifying the severity of the individual's illness experience [5]. All these findings point to the concept of ‘illness perceptions’ [6], where individuals create a cognitive model of their illness, which may influence their adjustment to a chronic condition.
This cognitive model is supported in CFS by the study of Moss-Morris et al. [7] who found that illness perceptions were related to levels of disability and psychological adjustment. The generalisability of their findings is limited as the CFS sample that they studied was of self-diagnosed cases obtained through the Australian and New Zealand Myalgic Encephalomyelitis Society (ANZMES) — a national postal-based community service. The use of this sample poses several problems. The study relied on self-identified sufferers who may not have fulfilled CFS operational criteria [8]. Secondly, a further selection bias is that the ANZMES is a self-help organisation and one follow up study [9] found that members of self-help groups had greater functional impairment than nonmembers. Finally, as discussed by Sharpe et al. [9], patients who believe they have ‘M.E.’ may have different illness characteristics from those who consider themselves to be CFS sufferers — that is, greater disability, but less psychological distress.
For these reasons, it was felt important to reassess the role of illness perception in a less selected clinic sample of CFS patients, comprehensively assessed according to recent CDC criteria [8]. It was aimed to assess which illness perception components had greatest influence on disability (fatigue) and adjustment (mood), and to explore the relative importance of mood and illness perception components on fatigue.
Section snippets
Characteristics of clinic sample
The patients contacted for this study (n=173) had attended a CFS clinic in tertiary care. They were chosen randomly from a database of 355 consecutive referrals between June 1995 and February 1997 who all fulfilled both the Oxford criteria for CFS [10] and the 1994 CDC criteria for CFS [8]. All patients had a primary complaint of chronic disabling mental and physical fatigue and were firstly assessed by an infectious diseases physician (PS), then by a liaison psychiatrist (SL). Patients with
Initial analysis
At the time of the survey, 29.8% of the respondents were HAD depression ‘cases’ and 32.3% were anxiety ‘cases.’
The ‘illness identity’ component of the Illness Perception Questionnaire showed the principal causes to which illness onset was ascribed. Eighty-eight (69.6%) patients believed that a germ or virus was the trigger for CFS. Most respondents did not accept any ‘emotional’ explanation for the condition, with only 34 (27%) believing a cause may have been their ‘own behaviour,’ and only 29
Discussion
This study had a large, thoroughly assessed sample of clinically diagnosed CFS sufferers, and confirmed that illness perceptions can explain a significant percentage of variance in levels of emotional adjustment (depression and anxiety) and, to a lesser degree, levels of fatigue in CFS. Less than a third of the sample were HAD anxiety or depression cases, yet, the correlations found suggest that those who did have significant mood disturbances and higher fatigue levels also had more
Acknowledgements
We thank Drs. D. Hargreaves, S. Rashid and G. Hill, K. Suresh for the assessment of patients and are grateful to Dr. Peter Trigwell, Consultant Liaison Psychiatrist, Leeds General Infirmary, for his advice on the use of the Illness Perception Questionnaire. A grant from Leeds CMHS Trust Charitable Funds funded Rupalee Suresh, grants from Shire Pharmaceuticals and the Northern and Yorkshire NHS Executive R&D Directorate funded Rachel Edwards. Paul Clarkson was funded by Northern and Yorkshire
References (17)
- et al.
The impact of catastrophic beliefs on functioning in chronic fatigue syndrome
J Psychosom Res
(1995) - et al.
Illness perception and symptom components in chronic fatigue syndrome
J Psychosom Res
(1992) - et al.
Development of a fatigue scale
J Psychosom Res
(1993) Somatization, illness attribution and the sociocultural psychiatry of Chronic Fatigue Syndrome
- et al.
Coping and other predictors of outcome in chronic fatigue syndrome: a 1-year follow-up
J Psychosom Res
(1997) - et al.
Psychosocial correlates of illness burden in chronic fatigue syndrome
Clin Infect Dis
(1994) - et al.
Illness representations and coping with health threats
- et al.
Functioning in chronic fatigue syndrome: do illness perceptions play a regulatory role?
Br J Health Psychol
(1996)