Personality and chronic fatigue syndrome: Methodological and conceptual issues☆
Introduction
This article's main concern is the study of personality in the chronic fatigue syndrome (CFS). CFS is a syndrome of unknown origin. It is mainly characterized by a severely disabling fatigue and it is commonly associated with symptoms such as myalgias, headache, sleep disturbance, swollen lymph nodes and cognitive impairment. In recent years CFS has become a growing concern, not only for patients suffering from the illness and for their families, but also for medical science, clinical psychology and society in general.
Some of these concerns already become apparent in defining what CFS is. In many cases, it is difficult to distinguish between idiopathic chronic fatigue, CFS and other unexplained medical conditions such as fibromyalgia, tension headache and irritable bowel syndrome, as these seem to be very similar and substantially overlapping (Aaron and Buchwald, 2001, Wessely et al., 1999). As no causes for CFS are found and definite markers for the illness are absent, the diagnostic process is usually extended and patients have to go through a whole battery of laboratory tests, physical examinations and psychological investigations before they are diagnosed with CFS. In 1988, the US Centers of Disease Control (CDC) proposed a set of diagnostic criteria to facilitate scientific research into CFS (Holmes et al., 1988). However, these criteria were criticized, not only because a large number of symptoms had to be present for a diagnosis of CFS, which might bias in favor of psychiatric morbidity (Katon & Russo, 1992), but also because it excluded such conditions as anxiety and depression, which some propose to be a result of the syndrome (Ray, 1991, Van Hoof et al., 2003). Therefore, less restrictive criteria were developed, amongst others in the UK by Sharpe et al. (1991). Consequently, the CDC criteria were also revised (Fukuda et al., 1994). At present these criteria are generally accepted and used for international research purposes. In Table 1 these criteria are presented.
Estimations on the prevalence of CFS range from 37/100 000 (Lloyd, Hickie, Boughton, Spencer, & Wakefield, 1990), to 75–267/100 000 (Buchwald et al., 1995), and even 740/100 000 (Lawrie, Manders, Geddes, & Pelosi, 1997). However, these numbers are difficult to compare as different populations were studied and varying CFS case definitions were used. Estimations on the incidence of CFS are rare but, based on their assumptions with regard to the prevalence of CFS, Lawrie et al. (1997) estimated the annual incidence of CFS to be 370/100 000.
Full recovery from CFS is unusual. In a recent review (Cairns & Hotopf, 2005) of studies on the prognosis of CFS, it was found that the median full recovery rate was only 5% and the median proportion of patients who had improved during follow-up was 39.5%. The prognosis for children and adolescents however, is generally somewhat better (Patel, Smith, Chalder, & Wessely, 2003). In a recent follow-up study of adolescent patients with CFS (Gill, Dosen, & Ziegler, 2004) it was found that, at a mean of 4.57 years after initial examination, 25% of the patients showed near to complete improvement and 31% showed partial improvement.
Etiological studies into the possible causes of CFS have been abundant. Active viral infection has frequently been associated with the symptoms of CFS, but evidence for this hypothesis has not consistently been found. There appear to be no significant differences between patients with CFS and healthy controls in the prevalence of human herpes viruses, Epstein–Barr virus, cytomegalovirus, hepatitis C virus, adenovirus and parvovirus B19, amongst many others. (Buchwald et al., 1996, Koelle et al., 2003, Wallace et al., 1999).
Immune dysfunction is another possible etiological factor that has been widely studied. Chronic lymphocyte overactivation with cytokine abnormalities in patients with CFS, associations between T cell markers and CFS, and associations between low natural killer cells and CFS have all been reported (Patarca-Montero et al., 2001, Straus et al., 1993). However, in a recent systematic review of the immunology of CFS, the authors noted that studies supporting almost any conclusion regarding the presence, or absence of immunological abnormalities in CFS could now be found, and concluded that no consistent pattern could be identified (Lyall, Peakman, & Wessely, 2003).
The same holds true of studies on the role of the neuroendocrine system in CFS. Disturbed neuroendocrine–immune system interactions, low circulating cortisol, high nocturnal melatonin, abnormalities in the relationship between cortisol and central neurotransmitter function, a disturbance of neurotransmitters in HPA axis function, and alterations in adrenal function in CFS have all been suggested and some evidence for these claims has been found (Cleare et al., 2001, Demitrack et al., 1991, Kavelaars et al., 2000, Knook et al., 2000, Segal et al., 2005). Again however, in an extensive review on the neuroendocrinology of CFS, it was concluded that no consistent evidence of abnormalities could be found and that it was unclear whether neuroendocrine changes (if any) are primary or secondary to behavioral changes in sleep or exercise (Parker, Wessely, & Cleare, 2001).
Along other lines of research, the psychiatric status of patients with CFS has received much attention. Several studies have reported a high prevalence of current psychiatric disorders in CFS, predominantly depression, somatization disorder and hypochondria (Ciccone et al., 2003, Schweitzer et al., 1994). However, while some studies concluded that psychiatric illness in many cases predated the development of CFS (Katon et al., 1991, Lane et al., 1991), other studies concluded that psychiatric disorder was concurrent with the onset of CFS and therefore more likely to be a consequence of, rather than a risk factor to CFS (Axe and Satz, 2000, Hickie et al., 1990). In that case, CFS is not seen as a manifestation of an underlying psychiatric disorder and more somatic causes are presumed (Komaroff & Buchwald, 1998).
Neuropsychological deficits and impaired cognitive functioning in patients with CFS have also received widespread attention, and have frequently been implied to be an important explanatory factor for some of the symptoms of CFS. People with CFS often complain of difficulties with memory and concentration. Several studies have described an impaired cognitive performance of patients with CFS on neuropsychological tests measuring speed of information processing, memory, motor speed and executive functioning (Busichio et al., 2004, Cluydts and Michiels, 2001). Problems with neuropsychological functioning were found to be unrelated to depression, fatigue or anxiety (Short, McCabe, & Tooley, 2002) and have instead been related to low levels of physical activity (Vercoulen et al., 1998), a more extensive use of frontal and parietal brain regions (Lange et al., 2005) and even genetic traits (Mahurin et al., 2004). In contrast with this, many other studies have found no difference in cognitive performance between patients with CFS and controls, and no evidence of any neuropsychological deficits in CFS (Fry and Martin, 1996, Schmaling et al., 1994). However, although in many studies objectively no cognitive differences between patients with CFS and controls are found, patients with CFS consistently report cognitive complaints and underestimate their actual performance on neuropsychological tests. This difference between the subjective perception of cognitive impairment and the absence of any objective evidence has led some researchers to speculate that, in contrast to laboratory cognitive tests, in CFS everyday cognitive tasks may require excessive processing resources leaving patients with CFS diminished spare attentional capacity (Wearden & Appleby, 1996), and other researchers to suggest that patients with CFS set impossibly high standards of personal performance (Metzger & Denney, 2002).
Other risk factors for the development of CFS that have been implied (and for which some evidence has been found) are birth order (Brimacombe, Helmer, & Natelson, 2002), family reinforcement of illness behavior (Brace, Scott-Smith, McCauley, & Sherry, 2000), maternal overprotection in relation to the formation of belief systems about activity avoidance (Fisher & Chalder, 2003) and a family history of physical and mental illness (Endicott, 1999). However, as with all of the etiological studies that have been discussed so far, the contrary conclusions can also be found. In a large birth cohort study into childhood predictors of CFS in adulthood, in which more than 11 000 people were followed up until the age of 30, no associations between maternal or child psychological distress, parental illness or birth order, and an increased risk of lifetime CFS were identified (Viner & Hotopf, 2004).
There have also been many studies into possibly effective treatment strategies for CFS. However, presently there is no established, universally beneficial intervention for the management and treatment of CFS (Whiting et al., 2001). With regard to medical and pharmacological treatment, amongst others, intramuscular dialyzable leukocyte extract (Lloyd et al., 1993), intravenous immunoglobulin (Vollmer-Conna et al., 1997), hydrocortisone (McKenzie et al., 1998) and antidepressants (Vercoulen et al., 1996, Natelson et al., 1998) were investigated in placebo-controlled studies, without proving their effectiveness. Recently, the effects of galantamine hydrobromide (Blacker et al., 2004), polynutrient supplements (Brouwers, Van der Werf, Bleijenberg, Van der Zee, & Van der Meer, 2002), homeopathic treatment (Weatherley-Jones et al., 2004) and corticosteroids (Kakumanu, Mende, Lehman, Hughes, & Craig, 2003) have been studied in randomized controlled trials, but were also found to be ineffective. At the moment, only cognitive behavior therapy (Price and Couper, 2000, Prins et al., 2001, Sharpe, 1998) and graded exercise therapy (Wallman et al., 2004, Edmonds et al., 2004) have shown some effectiveness, for a proportion of patients, in randomized controlled trials.
So, CFS seems surrounded by controversy. Patients are confronted with a highly ambiguous illness that severely incapacitates them. In addition to this they suffer from the consequences of the unclear medical status of the disease. Due to the uncertainties surrounding the etiology of CFS, its symptomatology and the overall objective ‘realness’ of the syndrome, they are likely to encounter disbelief concerning their medical condition (Friedberg & Jason, 2001). At present it is being discussed whether the impact of labeling patients with a diagnosis of CFS is enabling, or rather disabling (Huibers & Wessely, 2006). In the absence of a clear biological marker for the illness, which would permit a definite diagnosis instead of a descriptive one, based almost solely on the exclusion of other disease entities, patients are often faced with skepticism by their families, employers, insurance companies, psychologists and physicians. In a recent study on illness experience in CFS it was found that lack of illness recognition ranked high as a source of dissatisfaction for patients and was thought to aggravate psychiatric morbidity (Lehman, Lehman, Hemphill, Mandel, & Cooper, 2002). In contrast with this, physicians participating in a study on their perspectives on patients with CFS (Åsbring & Närvänen, 2003) expressed the view that patients seem to exaggerate the severity of their problems, and that there appears to be a discrepancy between their reported health and the way they look and behave.
Although it has been widely recognized that a positive and co-operative caregiver–patient relationship is of the utmost importance in the successful treatment of CFS (Sharpe, Chalder, Palmer, & Wessely, 1997), uncertainty and conflicts about the causal attribution of the syndrome, in many cases, put this relationship under pressure. Steven et al. (2000) showed that one-third of a group of more than two-thousand general practitioners did not believe that CFS was a distinct syndrome and thought the most likely cause was depression. This finding was confirmed by another study in which it became clear that while most of the doctors participating in the study believed CFS to have a psychological cause, all of the patients attributed their illness to a physical cause (Deale & Wessely, 2001). This disagreement over the perceived origins of CFS was thought to largely account for the fact that two-thirds of the patients in this study were dissatisfied with the quality of the medical care they had received.
This same dispute about the etiology of the syndrome, in combination with concerns about its nosological status, seems to have characterized and dichotomized medical and psychological thought on CFS. In spite of the great advances medical science has made in the explanation and treatment of diseases with an evident organic cause, the causes for CFS remain unclear and our understanding of the illness progresses only slowly. This “prototypical mind/ body problem” (Johnson, DeLuca, & Natelson, 1999, p. 258) seems to confront medicine with the limitations of the traditional paradigm, through which it has made such progress in the understanding and treatment of ‘classical’ diseases. As is now widely acknowledged the debates on chronic fatigue and immune dysfunction syndrome, neurasthenia, postviral fatigue syndrome, myalgic encephalomyelitis, chronic mononucleosis and chronic Epstein–Barr virus infection, as CFS was formerly known, were, and not uncommonly still are, characterized by a mind/body dualism that seems inherent to a biomedical model of thought, oriented towards monocausal explanation (Lewis, 1996, Taerk and Gnam, 1994, Ware, 1994). On the one hand, there are those who believe that CFS is initiated by a still unknown physical cause such as a chronic or relapsing viral infection, immunological deficiencies or abnormalities in the neuroendocrinological system. The absence of a clear and objective organic cause, on the other hand, leads others to relegate CFS to the realm of the mental and ‘subjective’ illnesses. In that case CFS is mostly thought of as a psychiatric disorder (e.g. a masked expression of depression, or a form of somatization), or a cognitive phenomenon.
However, a more logical explanation of the variety of findings and opinions on CFS would be that the illness is multi-factorial. Social, mental and somatic causes, and psychological and physical effects are not easily discernible, but instead appear to be interrelated. In recent years, a more biopsychosocial approach in the scientific research into CFS has become the standard (Main, Richards, & Fortune, 2000). In line with this approach (and in addition to the already mentioned studies) researchers have now also begun to study the iatrogenic factors in CFS (Deale & Wessely, 2001), associations in symptoms between patients with CFS and their parents (Van de Putte et al., 2006), the illness beliefs and attributions of patients with CFS (Deale et al., 1998, Van Houdenhove et al., 2000), the psychological adjustment of patients with CFS (Van Middendorp, Geenen, Kuis, Heijnen, & Sinnema, 2001), the health-related quality of life of patients with CFS (Hardt et al., 2001), the locus of health control in patients with CFS (Van de Putte et al., 2005), the relationship between ethnicity and CFS (Luthra & Wessely, 2004), the coping strategies of patients with CFS (Ax, Gregg, & Jones, 2001), the influence of family members in CFS (Gray et al., 2001), the cultural and historical context of CFS (Abbey and Garfinkel, 1991, Ware, 1994, Ware and Kleinman, 1992, Wessely, 1990, Wessely, 1996) and the personalities of individuals who have developed CFS (reviewed in this article).
So, within the biopsychosocial model of CFS one of the aspects studied, that might have a perpetuating and even a predisposing role in the syndrome, is the personality of people suffering from CFS. Among clinical psychologists, consulting physicians, scientific researchers and in society in general, a typical image has emerged of patients with CFS as perfectionist, conscientious, hardworking, somewhat neurotic and introverted individuals with high personal standards, a great desire to be socially accepted and with a history of continuously pushing themselves past their limits. (Lewis et al., 1994, Surawy et al., 1995). In addition to this, they are characterized as being particularly averse to any psychological or psychiatric explanation of the syndrome and extremely persistent in fixed beliefs concerning their illness, thereby reducing the chance of successful treatment (Sharpe, 1998). However, this image of people suffering from CFS was never really scrutinized, with most of the research activity concerning the individual with CFS focusing on psychopathology and possible psychiatric disorder.
The aim of this article is to (a) give a concise review of the main recent studies on personality and CFS, (b) address the major methodological problems in the study of personality in CFS and (c) discuss some of the conceptual assumptions that seem to limit the research on personality and CFS.
Section snippets
Selection of studies
The PubMed and PsychINFO databases from 1988 (when the original Centers for Disease Control criteria for CFS were first established) to November 2006 were searched using the keywords CFS and personality, CFS and psychology, CFS and individual, CFS and identity. On PubMed this generated 623 hits and on PsychINFO an additional 333 hits. All 956 abstracts were read. In addition the reference lists of the retrieved articles were examined.
The intention in the selection of studies was to include all
Results
Studying these results, it soon becomes obvious that the findings regarding the association of personality and CFS are not definitive. Although some studies seem to confirm, for a proportion of patients, some of the aspects of the aforementioned stereotype of people suffering from CFS, other studies found no such evidence. Some findings however, seem to be more consistent than others.
Study methods
An obvious reason for the discrepancies in the conclusions of the studies discussed might be the use of different methods to measure personality. This diversity seems almost inevitable when we consider the variety and divergence in health care settings and traditions of personality research. However, even when using the same instruments there often was no uniformity in the findings. In three studies, all using the Multidimensional Perfectionism Scale (MPS) for example, a remarkable lack of
Conceptual background of personality studies in CFS
As mentioned, the methods used to study personality in CFS are quite diverse. Nonetheless, in the approach of the reviewed studies, a shared conceptual model regarding the possible association of personality and CFS, and the appropriate way to scientifically study it, seems to be reflected.
Firstly, these studies have focused much of their attention on personality disorder. Psychological malfunctioning, rather than ordinary, non-pathological and everyday aspects of personality, which are
Conclusion
Every science, whether it be psychology, medicine, physics or sociology, is based on a set of conceptual assumptions. Usually, when these disciplines are functioning satisfactory, these presuppositions remain implicit and there is no need to make them explicit. However, when problems arise that seem difficult to solve with the normal instruments of these sciences, we have to focus our attention explicitly on these conceptual assumptions and ask ourselves whether our understanding of the problem
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The authors are grateful to Elise van de Putte, Coralie Fuchs, Gaston Franssen, Marc Slors and anonymous reviewers of this journal for their constructive remarks and suggestions on an earlier draft of this article. Preparation of this manuscript was supported by a Netherlands Organization for Scientific Research Grant (400-03-469).