The relationship of alexithymia to pain severity and impairment among patients with chronic myofascial pain

Journal of Psychosomatic Research 53 (2002) 823 – 830

The relationship of alexithymia to pain severity and impairment among patients with chronic myofascial pain Comparisons with self-efficacy, catastrophizing, and depression Mark A. Lumleya,*, Julie A. Smitha, David J. Longob a

Department of Psychology, Wayne State University, 71 West Warren Avenue, Detroit, MI 48202, USA b Department of Psychiatry, Geisinger Medical Center, Danville, PA, USA Received 29 May 2001; accepted 17 January 2002

Abstract Objective: Alexithymia is elevated among patients with chronic pain, but the relationship of alexithymia to the severity of pain among chronic pain patients is unclear. Also, studies have rarely examined whether alexithymia is unique from other, more widely studied constructs in the chronic pain literature (i.e., selfefficacy, catastrophizing, and depression), and research has not examined how alexithymia relates to the sensory versus affective dimensions of pain. Methods: Among 80 patients with chronic myofascial pain, we tested how alexithymia (Toronto Alexithymia Scale-20) was related to three competing constructs — selfefficacy, catastrophizing, and depression — and to the sensory and affective dimensions of pain as well as physical impairment. We then determined whether alexithymia remained correlated with pain and impairment when tested simultaneously with each of the three competing constructs. Results: Analyses controlled for patients’ sex, age, marital status, and duration of pain. Alexithymia was moderately correlated with less self-efficacy and greater catastrophizing, and substantially correlated with greater depres-

sion. Alexithymia was positively related to both affective pain and physical impairment, but was unrelated to sensory pain, whereas all three of the competing constructs were related to both types of pain as well as physical impairment. Regression analyses indicated that alexithymia remained a significant and independent correlate of affective pain severity while controlling for either self-efficacy or catastrophizing, but depression accounted for alexithymia’s relationship with affective pain. Also, alexithymia was no longer related to physical impairment, after controlling for any of the other three constructs. Conclusion: Although alexithymia is not related to the sensory component of pain, it is correlated positively with the affective or unpleasantness component of pain, independent of self-efficacy or catastrophizing. The emotional regulation deficits of alexithymia may lead to depression, which appears to mediate alexithymia’s relationship to affective pain. Alexithymia’s relationship with physical impairment appears to be better accounted for by self-efficacy or catastrophizing. D 2002 Elsevier Science Inc. All rights reserved.

Keywords: Alexithymia; Catastrophizing; Depression; Myofascial; Pain; Self-efficacy

Introduction Alexithymia is conceptualized either as a deficit in a person’s ability to employ cognitive processes to identify, differentiate, and communicate one’s affective states [1], or as a global impairment in conscious recognition of emotion [2]. Alexithymia is thought to impede successful regulation of emotions, particularly negative affects, resulting in chronic sympathetic hyperarousal, physiological sensations,

* Corresponding author. Tel.: +1-313-577-2838; fax: +1-313-577-7636. E-mail address: [email protected] (M.A. Lumley).

somatosensory amplification, and complaints of physical symptoms [3]. Alexithymia is elevated in numerous psychosomatic, psychiatric, and medical conditions [1,3]. In particular, studies have found elevated alexithymia among patients with chronic or persistent pain. For example, from one-third to 53% of patients with various types of persistent pain appear to be alexithymic [4– 6]. These percentages appear to be much higher than the base rate of alexithymia, which has been supported by studies that have included nonpain comparison groups. These studies have found higher levels of alexithymia among patients with psychogenic pain [7], rheumatoid arthritis [8], and inflammatory bowel disease [9]

0022-3999/02/$ – see front matter D 2002 Elsevier Science Inc. All rights reserved. PII: S 0 0 2 2 - 3 9 9 9 ( 0 2 ) 0 0 3 3 7 - 9

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than among controls. Our group found that alexithymia was greater among a sample of heterogeneous chronic pain patients than among patients seeking treatment for either obesity or nicotine dependence [10]. It is noteworthy, however, that in all of these studies, only about one-quarter to one-half of the chronic pain patients had elevated alexithymia scores, suggesting that there is much variability in alexithymia among people with chronic pain. Similarly, there are substantial individual differences in pain severity and disability among those with persistent pain. Some people report little pain and have minimal disability, whereas others complain of great pain and dysfunction. This raises the possibility that differences in alexithymia account for variations in the experience of pain and disability. Yet, the evidence for this is mixed. In support of this hypothesis, three studies of healthy people found that alexithymia was positively correlated with reported pain during experimental pain induction or during medical procedures [11 – 13]. In contrast, three studies of relatively large samples of patients with various chronic pain conditions found no relationship between alexithymia and pain severity [4– 6]. Thus, it remains unclear whether alexithymia is associated only with the presence of chronic pain per se, or is also associated with the severity of pain and disability among people with pain. Needed advances in research on alexithymia and pain A recent editorial argued that research on alexithymia and specifically on the most widely used instrument, the Toronto Alexithymia Scale-20 (TAS-20), needs to be advanced by simultaneously considering other constructs that might compete with alexithymia as predictors of clinically important criteria, and by determining what alexithymia does not predict [14]. Most research studies have assessed only alexithymia as the sole predictor of some criterion measure, without also reporting other competing predictor constructs. It is important to determine whether alexithymia is unique in its ability to predict a criterion, whether another measure predicts the criterion better, or whether another measure mediates alexithymia’s relationship with a criterion. Second, most alexithymia studies have reported only what alexithymia is related to or predicts, but not what it is unrelated to. Yet, the process of determining a measure’s discriminant validity is a necessary complement to determining its convergent validity. In this study, we sought to compare alexithymia to three widely studied predictor constructs in the chronic pain literature: self-efficacy, catastrophizing, and depression. Self-efficacy is the belief that one has the capacity to control pain and functioning in one’s daily activities. Pain-related self-efficacy is one of the most robust predictors of reduced pain and disability and better adjustment across a range of measures [15 –19]. One might hypothesize that alexithymia is related to reduced self-efficacy, but this has not yet been tested.

Catastrophizing also has been widely studied in the pain literature, and it is defined as the tendency to focus on and exaggerate the threat value of painful stimuli and to negatively evaluate one’s ability to cope with pain [20]. Many studies have demonstrated that catastrophizing is related to a number of pain-relevant outcomes, including higher reported pain [21,22], more overt pain behaviors [23], and more disability [22,24]. Like self-efficacy, catastrophizing also has not yet been studied in relation to alexithymia, but alexithymic people may be more prone to catastrophize, given the negative affective experience associated with both of these conditions. Finally, depression has been widely studied in both the chronic pain and alexithymia literatures. Chronic pain is often comorbid with depression [25,26], and alexithymia is also substantially related to depression and may predispose to it [1,3]. These observations suggest that depression may mediate the relationship between alexithymia and chronic pain. Indeed, recent research by Kosturek et al. [27] found that when depression was taken into account, alexithymia became unrelated to chronic pain, and de Zwaan et al. [28] found that depression, but not alexithymia, influenced thresholds to thermally and mechanically induced pain among patients with eating disorders. This study also sought to examine both the convergent and discriminant validity of alexithymia by differentiating two types of pain. Pain is not a single entity, but includes at least two dimensions. The International Association for the Study of Pain [29] defined pain as ‘‘an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.’’ The sensory component of pain refers to its intensity and patterning. It might be thought of as the ‘‘volume’’ of pain stimulation. In contrast, the emotional or affective component of pain can be thought of as the degree to which a person experiences unpleasantness. Differentiating these two dimensions is important because they are affected by different psychological and biological processes [30]. For example, psychosocial treatments and medications that alter emotional functioning generally influence pain’s affective dimension more than sensory dimension. The affective pain dimension appears to be regulated by the limbic system, whereas the sensory pain dimension is not. No prior studies of alexithymia have differentiated these two types of pain, but we hypothesized that alexithymia, which involves impaired emotional regulation, should be related to the affective component of chronic pain, but not to the sensory component of pain. Goals of the study This study had three primary goals. First, in order to better understand the construct validity of the TAS-20, we examined how it was related to three widely studied constructs in the pain literature — self-efficacy, pain catastrophizing, and depression — the first two of which have not

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previously been examined in relation to alexithymia. Second, we tested whether alexithymia is related to the affective but not the sensory component of pain, and we also included a measure of pain disability or physical impairment as a criterion because it remains unclear whether alexithymia is related to impairment. Third, we tested whether alexithymia had unique predictive validity for pain severity and impairment — accounting for variance in these criteria beyond that explained by the more widely studied constructs of selfefficacy, catastrophizing, or depression — and whether depression might mediate the relationship between alexithymia and pain severity. We also explored separately how each of the three facets of alexithymia, as measured by the TAS20, is related to the other predictors and to pain severity and impairment. We examined these relationships in a sample of patients with chronic myofascial pain, a group of interrelated muscular pain disorders that includes fibromyalgia and that are ranked among the most frequent causes of chronic pain [31].

Methods Participants Participants were 80 adults diagnosed with chronic myofascial pain (at least 6 months duration) who were patients at a large, regional medical center in rural Pennsylvania. Patients included 60 women (75%) and 20 men (25%), who averaged 48.67 years of age (S.D. = 11.82, range = 24– 86), and 58 (72.5%) were married or cohabiting. The mean duration of myofascial pain was 11.38 years (S.D. = 7.61, range 0.5– 35.0 years). All patients (except one Hispanic woman) were European American, reflecting the population base of the area. Procedures Medical records from the Departments of Anesthesiology (Pain Therapy Clinic), Rheumatology, and Psychiatry and Behavioral Medicine were reviewed to identify potential participants with a medically documented diagnosis of myofascial pain of at least 6 months duration. All identified patients had been diagnosed with a chronic myofascial pain condition with documented trigger points by board-certified physicians in Anesthesiology, Rheumatology, or Physical Medicine and Rehabilitation with 5 –20 years of experience in the diagnosis and treatment of chronic pain. All patients recruited from the Department of Psychiatry and Behavioral Medicine were also current or former patients of one of the medical departments (Anesthesiology or Rheumatology). Patients with dementia, psychosis, or mental retardation were excluded. Patients meeting eligibility criteria were approached for recruitment during routine outpatient visits or were sent a recruitment letter via the mail. All patients were provided a

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demographic and medical history survey as well as a set of questionnaires that included measures of alexithymia, selfefficacy, catastrophizing, depression, pain, and physical impairment. A total of 141 patients were identified as meeting study eligibility criteria and were contacted for recruitment. Sixty patients (42.5%) declined to participate (18 declined during outpatient recruitment, with most citing the length of time required as their reason, and 42 of the mail recruitment patients did not return the questionnaire packet). One patient returned a partially completed packet of questionnaires and was excluded, leaving a final sample of 80 patients. Predictor measures Alexithymia was assessed with the TAS-20 [32], which provides a global alexithymia score (TAS-20 total), as well as scores on three facets or subscales: difficulty identifying feelings and distinguishing them from bodily sensations, difficulty describing ones’ feelings, and a preference for externally oriented thinking. Items are rated on a 1 –5 scale and summed; higher scores indicate greater levels of alexithymia. The construct validity of the TAS-20 has been demonstrated in numerous studies [1]. In our sample, the TAS-20 total had acceptable internal consistency (a = .84), as did the first two facets (difficulty identifying feelings: a = .83; difficulty describing feelings: a = .73), but not the third facet (externally oriented thinking: a = .47). Taylor et al. [1] have suggested that people with TAS-20 total scores greater or equal to 61 can be classified as alexithymic, whereas those with scores less than or equal to 51 are nonalexithymic. Self-efficacy was assessed with the Chronic Pain SelfEfficacy Scale (CPSS [33]), a 22-item questionnaire that measures three aspects of pain self-efficacy: pain management, coping with symptoms, and physical functioning. Items were rated on a 10 –100 scale (with response points at each multiple of 10), and subscale means were calculated, with higher values indicating greater self-efficacy. Patients with high scores on CPSS subscales have been found to report less pain, disability, depression, hopelessness, and somatic preoccupation; and greater activity and perceived control [33]. Because the three subscales were highly intercorrelated with each other (r values from .67 to .76), we calculated the average of all 22 items to form a single variable, ‘‘self-efficacy.’’ The coefficient a for the full scale was .95. Catastrophizing was assessed with the six-item subscale from the Coping Strategies Questionnaire (CSQ [20]). These items were rated from 0 (never do that) to 6 (always do that) and averaged. Higher means indicate greater catastrophizing in response to pain. The CSQ has been the most widely used coping instrument in the pain literature. The catastrophizing scale, or the Pain Control and Rational Thinking factor of the CSQ, of which catastrophizing forms the major part, has consistently been related to numerous

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maladaptive pain outcomes [34]. The coefficient a in our sample was .90. Depression was assessed using the 20-item Center for Epidemiologic Studies — Depression Scale (CES-D [35]). The CES-D taps primarily affective and cognitive rather than somatic symptoms of depression, making it more appropriate for use with medical populations. Symptoms were rated on a 0– 3 scale for their frequency during the past month, and a total score was calculated. The CES-D discriminates well between general population and psychiatric samples and discriminates moderately well among levels of depression severity within patient groups. It also correlates positively with other measures of depression and negatively with measures of positive affect [35]. In our sample, we found an internal consistency of 0.93. Criterion measures Sensory and affective dimensions of pain were measured using the Pain Rating Index of the McGill Pain Questionnaire (MPQ [36]). Patients chose adjectives from 20 categories to describe their pain during the past month, and the sensory and affective pain scores were determined by summing the scores from the highest scoring adjective endorsed in each category. Research has shown that the MPQ is stable and highly internally consistent [30], and a number of studies have demonstrated the concurrent, predictive, and construct validity of its components [37,38]. Physical impairment in work, social– recreational, family, and marital activities during the past month was assessed with the nine-item Interference subscale of the Pain Experience section of the West Haven – Yale Multidimensional Pain Inventory (WHYMPI [39]). Items were rated on a 0 –6 scale and averaged; patients were given the option of responding ‘‘does not apply,’’ and these items were not included. Higher scores indicate greater interference due to pain. High 2-week stability of the WHYMPI has been found [39], and in this sample, the internal consistency was 0.98. Construct validity of the WHYMPI scales has also been demonstrated [37].

Results Statistical approach We first examined how alexithymia correlated with the other three predictor variables (self-efficacy, catastrophizing, and depression) as well as how the three criterion variables (sensory pain, affective pain, and impairment) correlated among themselves. Next, we examined how alexithymia and the other predictors were related to each of the three criteria. To better understand which facets of the TAS-20 were related to the other predictors and to the criterion variables, we also present relationships of each of the three facets of the TAS-20 with these other measures. Finally, we used hierarchical regression analyses to test whether global alexithymia remained significantly related to a criterion after statistically controlling for each of the three competing predictor variables: self-efficacy, catastrophizing, or depression. For all of these analyses, we sought to eliminate demographic variables and the duration of the pain problem as potential confounds. Thus, all correlations and regression analyses simultaneously controlled for the patient’s age, sex, marital status (married or not; cohabitation was considered married), and duration of pain in years. All significance tests were two-tailed using an a of .05. Partial correlations among predictor measures and among criterion measures Table 1 presents sample descriptive statistics for each of the variables in the study. Of note, the level of global alexithymia in this sample was relatively high — 32.5% of the sample scored in the alexithymic range, whereas 37.5% scored in the nonalexithymic range. Table 1 also presents the partial correlations (controlling for age, sex, marital status, and pain duration) among the four predictors and among the three criteria. Global alexithymia was moderately, inversely correlated with self-efficacy, and the two TAS-20 facets pertaining to feelings primarily contributed to

Table 1 Partial correlations (controlling for age, sex, marital status, and pain duration) among measures of alexithymia, self-efficacy, catastrophizing, sensory pain, affective pain, and physical disability (N = 80) Measure (1) (2) (3) (4) (5) (6) (7)

Alexithymia Self-efficacy Catastrophizing Depression Sensory pain Affective pain Impairment

All tests two-tailed. * P < .05. ** P < .01. *** P < .001.

2

3 .45***

4 .47*** .59**

5 .71*** .63** * .72***

6 .16 .32** .23* .23*

7 .39*** .43*** .42*** .44*** .68***

M (S.D.) .26* .59*** .44*** .49*** .41*** .41***

–

55.62 43.74 2.95 28.53 23.24 4.67 3.64

(11.58) (18.61) (1.65) (13.68) (8.43) (3.46) (1.54)

M.A. Lumley et al. / Journal of Psychosomatic Research 53 (2002) 823–830 Table 2 Hierarchical regressions of affective pain on alexithymia and competing variables (N = 80) DR2

b

t

.08 .02 .20 .00

0.58 0.19 1.75 0.01

.33 .25

2.74 2.18

.51 .56 .85 .08 .99 < .001 .008 .033

(2) Predictors .216 10.64 Catastrophizing Alexithymia Full model: F(6,73) = 4.24, P = .001, R2 = .258

.30 .25

2.60 2.15

< .001 .011 .035

(2) Predictors .196 9.37 Depression Alexithymia Full model: F(6,73) = 3.80, P = .002, R2 = .238

.35 .17

2.16 1.12

< .001 .034 .27

Block: predictor

F change

(1) Sociodemographics .042 0.83 Age Sex Marital status Pain duration (2) Predictors .223 11.07 Self-efficacy Alexithymia Full model: F(6,73) = 4.39, P = .001, R2 = .265

P

Each Step 2 was tested separately from the others. Marital status coded as 0 = no and 1 = yes.

this relationship [difficulty identifying feelings: partial correlation (pr) = .35, P = .002; difficulty describing feelings: pr = .37, P = .001; externally oriented thinking: pr = .16, P = .16]. Global alexithymia was positively correlated with catastrophizing, and again this was due primarily to the two facets related to feelings (difficulty identifying feelings: pr = .44, P < .001; difficulty describing feelings: pr = .34, P = .003; externally oriented thinking: pr = .13, P = .26). Finally, global alexithymia was substantially positively correlated with depression, and again this was due to the two facets pertaining to feelings (difficulty identifying feelings: pr = .65, P < .001; difficulty describing feelings: pr = .58, P = .003; externally oriented thinking: pr = .16, P = .16). With respect to the criterion measures, sensory and affective pain were positively correlated with each other, although they shared less than half of their variance (46%), suggesting that they tapped somewhat different components of pain. Both dimensions of pain correlated moderately with physical impairment. Correlations between predictor measures and criterion measures We next examined the partial correlations of alexithymia and the other three predictors with the three criteria. As shown in Table 1, alexithymia was not significantly correlated with sensory pain (nor were any of the TAS-20 facets; all P’s > .10). Global alexithymia, however, was significantly correlated with greater affective pain. Only the two TAS-20 facets pertaining to feelings were related to greater affective pain: difficulty identifying feelings (pr = .38, P < .001) and difficulty describing feelings (pr = .31, P = .006), but not

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externally oriented thinking (pr = .04, P = .76). Global alexithymia also was correlated with greater physical impairment, and again this was due to the two feeling-related facets (difficulty identifying feelings: pr = .28, P = .015; difficulty describing feelings: pr = .20, P = .08), but not to externally oriented thinking (pr = .05, P = .66). Self-efficacy was correlated with lower levels of both components of pain, and self-efficacy had a substantial correlation with lower levels of impairment. Both catastrophizing and depression correlated significantly with greater impairment and with higher levels of both components of pain, but especially with affective rather than sensory pain. Is alexithymia a unique correlate of affective pain and impairment? Because global alexithymia as well as all three competing measures (self-efficacy, catastrophizing, and depression) were correlated with both affective pain and with impairment, we next tested the uniqueness of alexithymia’s relationship with these two criterion measures. (We did not further analyze sensory pain in these regression models because it was not significantly predicted by alexithymia.) Tables 2 and 3 present the results of hierarchical regression models predicting affective pain and impairment, respectively, from the TAS-20 total score and each of the three competing measures. For each criterion measure, the four demographic/medical history variables were entered in the first step, and in the second step, global alexithymia and one of the three competing predictors were entered simultane-

Table 3 Hierarchical regressions of physical impairment on alexithymia and competing variables (N = 80) Block: predictor

DR2

F change

(1) Sociodemographics .058 1.15 Age Sex Marital status Pain duration (2) Predictors .327 19.41 Self-efficacy Alexithymia Full model: F(6,73) = 7.61, P = .0001, R2 = .385

b

t

P

.22 .07 .01 .24

1.66 0.61 0.04 1.89

.61 .01

5.59 0.06

.34 .10 .52 .97 .06 < .001 < .001 .95

(2) Predictors .185 8.90 Catastrophizing Alexithymia Full model: F(6,73) = 3.90, P = .002, R2 = .243

.40 .07

3.40 0.60

< .001 .001 .55

(2) Predictors .243 12.70 Depression Alexithymia Full model: F(6,73) = 5.25, P < .001, R2 = .301

.67 .18

4.33 1.25

< .001 < .001 .22

Each Step 2 was tested separately. Marital status coded as 0 = no and 1 = yes.

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ously. For each model, three separate Step 2s are presented — one with self-efficacy, one with catastrophizing, and one with depression as the variable simultaneously entered with alexithymia. Table 2 shows the results for the regressions predicting affective pain. As can be seen, when both alexithymia and self-efficacy were considered simultaneously, they both were significant, independent correlates of affective pain. Together, these variables accounted for about 22% of the variance in affective pain, beyond that accounted for by demographic/medical history variables. The same was true for catastrophizing — both alexithymia and catastrophizing were significant, independent correlates of affective pain, together accounting for about 22% of the additional variance. However, when depression was examined along with alexithymia as predictors of affective pain, only depression was a significant correlate of pain severity. Alexithymia was no longer related to affective pain after accounting for depression. As shown in Table 3, alexithymia made no unique contribution to the prediction of physical impairment beyond any of the three competing predictor measures. Self-efficacy, catastrophizing, and depression each remained unique correlates of impairment, beyond the influence of demographics. In all three models, the relationship of alexithymia to impairment fell to near zero when self-efficacy, catastrophizing, or depression was included.

Discussion This study has three major findings. First, in this sample of patients with chronic myofascial pain, alexithymia was moderately to highly correlated with three constructs that have been extensively studied in the chronic pain literature — self-efficacy, catastrophizing, and depression. Second, alexithymia was positively correlated with pain-related physical impairment and with one component of pain — affective pain — but not with sensory pain. Third, alexithymia remained a significant correlate of affective pain even when self-efficacy or catastrophizing was simultaneously considered. In contrast, depression accounted for and possibly mediated alexithymia’s relationship with affective pain. Moreover, alexithymia was not a unique correlate of physical impairment, which was better accounted for by each of the three competing constructs. Importantly, all of these relationships were independent of several potentially confounding demographic and medical history variables: the patient’s sex, age, marital status, and duration of the pain. We discuss each of these findings in turn. First, this study found that alexithymia overlapped moderately with both self-efficacy and catastrophizing, sharing from 20% to 22% of its variance with each of these other measures. The inverse relationship of alexithymia to selfefficacy may be due to the fact that alexithymia reflects a

deficit in abilities (in this case, of emotion regulation), whereas self-efficacy reflects greater abilities. The inverse correlation may also stem from patient’s observations of their ability to control pain. Those patients with good pain control may judge themselves to be self-efficacious, whereas those lacking pain control may judge themselves to be lacking various abilities, including emotional regulation. With respect to catastrophizing, it is likely that the common experience of unregulated negative emotion associated with both alexithymia and catastrophizing gives rise to the positive correlation between these two measures. Note that this study replicated the large body of literature on both self-efficacy and catastrophizing — self-efficacy was a robust correlate of less pain and impairment, and catastrophizing was correlated with increased pain and impairment. We also found that alexithymia and depression were substantially related, sharing about 50% of their variance. Although alexithymia and depression have routinely been found to be related to each other, the very strong relationship in this study may be due to the relatively high levels of both alexithymia and depression found in this sample, which might have allowed for a greater magnitude of the correlation. We examine the role of depression in more detail below. Second, this study suggests a new way of thinking about alexithymia’s relationship with pain severity among chronic pain patients. This study suggests that alexithymia is not related to the intensity or sensory qualities of pain, but alexithymia is related to the affective dimension or unpleasantness of pain. This finding is consistent with a larger literature on the role of emotion and emotional regulation in influencing the pain experience. Negative mood states and negative emotions primarily influence one dimension of pain — that component that is regulated through the limbic system and corresponds to the suffering or unpleasantness of the pain experience. In contrast, the sensory dimension of pain appears to be modulated via neural processes that are less influenced by emotion. Thus, it is reasonable that alexithymia is less related to sensory pain. We suspect that studies that assess pain unidimensionally among chronic pain patients will fail to find a relationship with alexithymia, unless the affective component of pain is assessed separately. The fact that self-efficacy, catastrophizing, and depression were all related to both alexithymia and to affective pain and impairment raises the question of whether alexithymia makes a unique contribution to pain and impairment. We found mixed support for this proposal. When considered simultaneously along with either self-efficacy or catastrophizing, both alexithymia and these other two variables were significant predictors of affective pain. This implies that the emotional regulation deficits found in alexithymia are sufficiently distinct from self-efficacy beliefs and catastrophizing and that emotional regulation difficulties also contribute to the experience of affective pain. Thus, knowing a patient’s alexithymia level can

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increase one’s ability to account for the patient’s experience of affective pain. In contrast, alexithymia had no unique predictive validity of affective pain after controlling for depression, whereas depression remained predictive of affective pain after controlling for alexithymia. This finding is consistent with the proposal that depression mediates alexithymia’s relationship with affective pain. Alexithymia is hypothesized to interfere with adaptive emotion regulation, resulting in negative affects such as depression, which then influences the affective pain experience. This proposal is consistent with the findings of Kosturek et al. [27] in their study of alexithymia, depression, and chronic pain. Moreover, the analysis of the subscales or facets of the TAS-20 supports this. The two facets of the global alexithymia construct that deal with feelings (difficulty identifying feelings and difficulty describing feelings), rather than externally oriented thinking, accounted for the TAS-20’s relationships with depression (as well as self-efficacy and catastrophizing) and affective pain and impairment. Externally oriented thinking was essentially unrelated to these other variables. This pattern (the first two facets of the TAS-20 are the best or sole predictors) has been found in a number of studies of widely differing outcome measures, and suggests that the affective rather than the cognitive/attentional aspects of alexithymia are more central to the global construct’s predictive validity. However, it must be noted that the externally oriented thinking facet had quite low reliability in this study (as it has in other studies), which may have contributed to its lack of validity. Alexithymia had a weaker relationship with physical impairment, and alexithymia made no unique contribution to understanding impairment beyond the effects of selfefficacy, catastrophizing, or depression. Other studies have also found that alexithymia has either no relationship [4] or a weak relationship [5] to physical impairment, perhaps because affect regulation is less closely related to behavior than it is to subjective experience (i.e., affective pain). Implications and future directions As noted in the Introduction, studies of chronic pain patients have not found associations between alexithymia and global pain intensity ratings. Our study suggests that this may be because the two components of pain need to be differentiated, and when this is done, one will find that alexithymia is related to the affective but not sensory component of pain. Yet, as also noted earlier, alexithymia does appear to be related to increased pain severity or intensity among healthy people when exposed to acute invasive procedures or laboratory pain. This suggests that another confound in understanding the relationship of alexithymia to pain is the sample studied — whether healthy people or those with chronic pain. It may be that those who develop chronic pain are a psychologically unique subset of people from the larger population, and

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alexithymia, which is higher among those in chronic pain, predicts sensory pain differently in the two groups. Alternatively, it may be that the process of living with pain changes the relationship between alexithymia and sensory pain, so that alexithymia becomes related only to the affective component of pain over time. These issues need to be addressed in future work. Another consideration for the literature on alexithymia and pain is the fact that research on patients with chronic pain is not the same thing as research on people with chronic pain. To our knowledge all studies on chronic pain and alexithymia have been conducted on medical patients who have sought treatment for their pain. These studies have found elevated levels of alexithymia in these patients, as we did in this study — we found that 32.5% of the sample met the TAS-20 cut score for alexithymia. Yet, it is increasingly recognized that people who seek medical care have elevated distress and negative affect compared with people with comparable medical problems who do not seek medical care [40 – 43]. Further, in our study, some of the patients were recruited from psychiatry, and these patients may have had even greater levels of distress than patients recruited from medical clinics. It is possible that people with a pain problem who seek medical (or psychiatric) care and subsequently become participants in research studies are those who have experienced increased affective pain and suffering in particular, and because alexithymia is associated with affective pain, these treatment seekers may be more highly alexithymic. An interesting research question is whether alexithymia is elevated among people who have chronic pain but who do not seek treatment. It should be noted that these results were obtained on a sample of patients with myofascial pain, and whether the results can be generalized to people with other chronic pain problems needs to be determined. Also, the utility of alexithymia to predict changes in sensory and affective pain across time needs to be studied using a prospective design. Yet, the results of this study suggest that the assessment of alexithymia may increase our understanding of the affective or unpleasantness dimension of pain, beyond that explained by self-efficacy or catastrophizing, and that alexithymia may lead to more affective pain via increases in depression. Research should examine whether the effectiveness of cognitive – behavioral pain interventions, which have been directed primarily at increasing patients’ self-efficacy and decreasing their catastrophizing, can be improved by including emotional regulation processes such as teaching affect awareness, encouraging emotional disclosure, and facilitating affective expression.

Acknowledgments We thank Drs. Stephen Paolucci, Charles Huston, and Richard Neuman for their assistance in patient recruitment, and Jason Nupp for his assistance in data collection.

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