Original contribution
Alexithymia in patients with psoriasis: Clinical correlates and psychometric properties of the Toronto Alexithymia Scale-20

https://doi.org/10.1016/j.jpsychores.2004.03.009Get rights and content

Abstract

Objective

The objective of this study was to examine the psychometric properties and clinical correlates of the 20-item Toronto Alexithymia Scale (TAS-20) in patients with psoriasis.

Methods

Three hundred patients with psoriasis completed the TAS-20 and had the severity of their psoriasis clinically assessed. Test–retest reliability was assessed over 10 weeks in a subset of 71 patients receiving standard medical treatment for their psoriasis. Examination of the factor structure employed both exploratory (EFA) and confirmatory (CFA) factor analysis techniques.

Results

The overall prevalence of alexithymia in this population of psoriasis patients, as indicated by the TAS-20, was 33%. The TAS-20 total score was not related to clinical severity, age, age at onset or duration of psoriasis. The 10-week test–retest reliability on a sample of 71 psoriasis patients, pre- and posttreatment with photochemotherapy, was found to be acceptable (r=.69; P<.001). EFA produced no stable solutions. The three-factor structure of the TAS-20 using CFA was also not replicable in this sample.

Conclusions

The findings of this study support the contention that alexithymia is not significantly influenced by either disease severity or chronicity in patients with psoriasis. It is recommended that when employing the TAS-20 in patients with psoriasis, caution is exercised in the interpretation of the scale scores and that further psychometric evaluation of the scale is undertaken as appropriate.

Introduction

One principle of psychosomatic medicine is that deficits in the experience and expression of emotions can have a harmful effect on health. In 1973, the label alexithymia was given by Sifneos [1] to assign a group of cognitive and affective characteristics typical of many patients with psychosomatic disorders. The definitions of alexithymia have been refined, and it is viewed currently as a deficit in the self-regulation of affect [2]. It is suggested that individuals with alexithymia have an impaired ability to build mental representations of emotions, that ordinary somatosensory information is magnified and physical symptoms of emotional arousal are misinterpreted as indicators of physical illness [2]. Subsequently, the concept of alexithymia has taken on a role as a key player within psychosomatic medicine.

High prevalence rates of alexithymia have been identified in patients with a variety of health problems. Alexithymia has been associated with poorer metabolic control in patients with diabetes [3], reductions in immunocompetence in women with cervical neoplasia [4] and blood pressure elevations in patients with hypertension [5]. However, other studies have reported no such associations between alexithymia and conditions such as ischaemic heart disease [6], insulin-dependent diabetes mellitus [7] and breast cancer patients [8]. Thus, findings tend to be equivocal.

Psoriasis is a condition that has often been construed as being the result of personality factors and is associated with an array of physiological [9], behavioural [10], cognitive–affective [11] and social [12] difficulties. As such, psoriasis would appear to be a prime candidate for the investigation of alexithymia. Psoriasis is a chronic, inflammatory, currently incurable dermatological condition. It affects 2–3% of the population, has an equal distribution between the sexes, and its onset may occur at any age. Studies have indicated that genetic factors have an important role in the onset of psoriasis [13]. Psychological distress and stressful life events have been shown to be important in the onset, exacerbation and maintenance of the condition [14], [15], [16]. Ever-increasing evidence links chronic low-grade stress to maintenance of the condition [17]. Increasingly psoriasis is recognised to be associated with wide-ranging psychological distress, including anxiety [18], depression [19], disability [20] and pathological worrying [21].

For many years, psoriasis was considered to be a psychosomatic condition, predisposed by certain personality types. However, research to date has not confirmed higher prevalence of alexithymia for patients with psoriasis. Fava et al. [22] compared the alexithymic scores of 20 patients with psoriasis, chronic urticaria and cutaneous infections but did not find significantly higher alexithymic scores in psoriasis patients compared with the two other conditions. Rubino et al. [23], using the Toronto Alexithymia Scale (TAS), found that while patients with psoriasis did score higher on this measure relative to controls, the difference did not reach statistical significance. One recent study [24] found a trend for psoriasis patients with recent exacerbations to have higher scores on the 20-item TAS (TAS-20) than those with other skin conditions. Using the total scale score of the TAS, Allegranti et al. [25] found a significant difference between the patients with psoriasis and the controls. Patients with psoriasis were also more likely to score above the cutoff for borderline alexithymia than the controls. Other studies [26] have reported evidence that alexithymia may also be closely tied up with the construct of anxiety sensitivity, and, as such, it has been suggested that it may be important in accounting for poor psychological adjustment in patients with psoriasis [27].

Unfortunately, previous research investigating alexithymia in patients with psoriasis has been rendered unsatisfactory by the use of inadequate assessment instruments and different methods of investigating the construct. The TAS-20 [28], [29], which was constructed with regard to specific theoretical concerns, has been considered the best and most frequently used method in the measurement of alexithymia [30]. The TAS-20 is said to have a three-factor structure based on theoretical constructs comprising of (i) difficulty identifying feelings (DIF); (ii) difficulty describing feelings (DDF); and (iii) externally orientated thinking (EOT). A number of studies have replicated this factor structure across both clinical and nonclinical populations [31], [32]. However, some studies have failed to confirm the factor structure of the TAS-20 and have suggested exercising caution in its use [33], [34]. It has been suggested that some of these confounding results have been due to variations in the factor analytic techniques employed, in that some studies have used exploratory models whereas others have preferred confirmatory models as a means of testing specific hypotheses [31]. A recent study [35] employed the TAS-20 in a community population in Canada and reported results of the confirmatory factor analysis (CFA), which supported the original three-factor structure. They propose that the exploratory factor analysis (EFA) approach is better suited to studies where little is known about the concept being developed, and as such, within the field of alexithymia, CFA is more appropriate. However, there still remains some criticism of the three-factor fixed model identified in CFA studies [33], [34]. Haviland and Reise [34], using CFA, reported that none of the various factor solutions produced a simple structure in either a medical student or psychoactive-substance-dependent inpatient sample, although in this study, a number of the goodness-of-fit indices were at or just short of the criterion level. Recently, Müller et al. [36] tested a range of factor structures of the TAS-20 in different populations of subjects and concluded that the factor structure of the instrument may vary across clinical and normal adult samples, going some way towards explaining the divergence in results across studies.

Given the presence of alexithymia as an essential element in the genesis and maintenance of various psychosomatic pathologies, it was considered important to examine the prevalence of alexithymia in patients with psoriasis and investigate the degree to which it is associated with clinical aspects of the condition. For both clinical and research purposes, it was also considered pertinent to examine the psychometric properties of the TAS-20.

Section snippets

Participants

Three hundred consecutive patients with chronic plaque psoriasis attending a hospital-based psoriasis specialty clinic had their psoriasis assessed by a dermatologist and completed the TAS (TAS-20). Participants were excluded if they had any other general medical condition, with the exception of psoriatic arthritis. Test–retest reliability over 10 weeks was assessed in a subsample of these patients returning to the clinic for standard pharmacological treatment of their condition. The study

Description of study population

Of the 300 patients participating, 46% were female and 54% male. They were aged between 18 and 80 years (mean 43.4, S.D. 12.1). The mean severity of their psoriasis, as assessed by the PASI, was 8.7 (S.D. 6.21) and ranged between 0 and 51.8. The age at disease onset ranged between 2 and 72 years, with a mean of 23.5 (S.D. 14.3). The mean duration of psoriasis was 19.9 years (S.D. 11.8) and ranged between 6 months and 60 years. Twelve percent of the patients had psoriasis for less than 5 years,

Discussion

The examination of alexithymia has been increasingly employed within investigations of patients with psoriasis. The findings of the current study have provided important information in relation to the psychometric properties of the TAS-20 and its relationship with clinical correlates of psoriasis.

Thirty-three percent of the current sample of psoriasis patients scored above the cutoff for alexithymia. This is comparable with that reported in inflammatory bowel disease (35%) [47] and myocardial

Acknowledgments

This study was supported by the NHS Executive Research and Development Programme for Physical and Complex Disabilities (Grant No: PCD2/A1/284).

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