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Previous research on substance use disorders (SUD) has yielded conflicting results concerning whether alexithymia is a state or trait, raising the question of how alexithymia should be addressed in the treatment of SUD-patients. The absolute and relative stabilities of alexithymia were assessed using the Toronto Alexithymia Scale (TAS-20) and its subscales. In total, 101 patients with SUD were assessed twice during a 3-week inpatient detoxification period while controlling for withdrawal symptoms and personality disorder traits. The relative stability of the total TAS-20 and subscales was moderate to high but showed remarkable differences between baseline low, moderate, and high alexithymic patients. A small reduction in the mean levels of the total TAS-20 scores and those of one subscale revealed the absence of absolute stability. The levels of alexithymia were unrelated to changes in withdrawal symptoms, including anxiety- and depression-like symptoms. The differences between low, moderate, and high alexithymic patients in terms of the change in alexithymia scores between baseline and follow-up indicated a strong regression to the mean. The findings suggest that alexithymia in SUD patients as measured using the TAS-20 is both a state and trait phenomenon and does not appear to be related to changes in anxiety- and depression-like symptoms.

Alcohol misuse is an important public health problem that is related to mortality, reduced economic productivity, and other serious health-related issues (Ezzati et al., 2002 and Smit et al., 2006). The abuse of and addiction to substances, including alcohol and nicotine, cost the USA nearly 600 billion dollars a year in medical, economic, criminal, and social expenses (Harwood, 2000 and Office of National Drug Policy, 2004). Therefore, obtaining insight into the risk factors of substance use disorders (SUD) is important for developing novel methods to prevent and reduce substance-related harm. Alexithymia may be a risk factor for SUD, particularly in the context of alcohol use disorders (AUD) (Taylor et al., 1997). Alexithymia is considered to be a deficit in emotion processing. More specifically, characteristics include difficulty identifying and describing feelings as well as discriminating between feelings and physical sensations. Individuals with alexithymia also show deficits in externally oriented thinking and are limited in their ability to fantasize or use their imagination (Sifneos, 1973). Overall, 45–67% of patients with SUD exhibit alexithymia (Taylor et al., 1997 and Thorberg et al., 2009). There are indications that frontal lobe functioning is associated with alexithymia (Lyvers et al., 2011), and the association between alexithymia and alcohol use is mediated by anxious attachment (Thorberg et al., 2011a), alcohol expectancy (Thorberg et al., 2011b), and drinking motives (Bruce et al., 2012). Early findings demonstrated a negative association between alexithymia and treatment-related outcomes, particularly in patients with AUD (Ziolkowski et al., 1995, Loas et al., 1997 and Cleland et al., 2005). In three recent studies, alexithymia was unrelated to abstinence, attrition, or changes in AUD- or SUD-related problems following treatment (de Haan et al., 2011, de Haan et al., 2012b and Stasiewicz et al., 2012). However, alexithymia was associated with poor emotion regulation skills (Stasiewicz et al., 2012), which predict post-treatment levels of alcohol use (Berking et al., 2011) and may increase the risk for relapse (Bandura et al., 2003). Therefore, alexithymia remains a relevant problem in optimizing the treatment of SUD, particularly in patients with AUD. An important clinical question is whether alexithymia is a mental state or a stable personality trait. In their review on alexithymia and SUD, Taylor et al. (1997) assumed that affective distress may contribute a state-dependent component to alexithymia. However, the high rates of alexithymia in SUD-patients in a stable phase of rehabilitation and with long lasting abstinence suggest an underlying trait structure as well (Taylor et al., 1997). In statistical terms, a stable personality trait is characterized by absolute and relative stability. Absolute stability refers to mean-level differences over time, which indicate whether and in which direction an entire sample or population is changing (Caspi et al., 2005 and Roberts et al., 2006). However, individual differences in change reflect deviations from the overall mean level patterns. Relative stability, which is defined as the extent to which relative differences between subjects remain the same over time (Roberts and DelVecchio, 2006), is therefore an even more important indication of the stability of a trait. Relative stability is reflected in the strength of test–retest correlations. Previous research revealed that alexithymia was not a stable personality trait in a sample of patients with SUD following inpatient treatment (de Haan et al., 2012a). A strong “regression to the mean” was found, indicating that low alexithymic patients with SUD at baseline scored higher at follow-up and high alexithymic patients at baseline scored lower at follow-up. The results also revealed large differences in relative stability between low, moderate, and high alexithymic patients with SUD. Both findings argue against alexithymia as a stable personality trait (de Haan et al., 2012a). We discussed in a previous article that absolute and relative stability in total TAS-20 or TAS-20 factor scores vary for different populations, including the general population and patients with diverse psychiatric disorders, which causes an extensive debate on the state versus trait concept of alexithymia in the literature (de Haan et al., 2012a). Other alexithymia stability studies in SUD or AUD populations were conducted with detoxifying or recently detoxified patients and reported conflicting results. One study found a relative change of alexithymia in newly abstinent alcoholic inpatients, suggesting that alexithymia in SUD-patients is a state phenomenon (Haviland et al., 1988). In this study the change in alexithymia was not related to a change in depression-like symptoms, measured with the Beck Depression Inventory (BDI) (Beck and Steer, 1987 and Haviland et al., 1988). However, in a subsequent study, Haviland et al. (1994) demonstrated with path analyses that a state of alexithymia in SUD-patients can result from severe anxiety- and depression-like symptoms, measured with the State-Trait Anxiety Inventory (STAI) (Spielberger, 1983) and the BDI. Another study (Pinard et al., 1996) reported no changes in the mean levels following detoxification and concluded that alexithymia is a stable trait. Only Haviland et al. (1988) investigated absolute and relative stability simultaneously. More recently, an absolute reduction in alexithymia was observed in patients with AUD during withdrawal, with high relative stability over a brief time period (de Timary et al., 2008). Alexithymia was defined in this previous study as a stable personality trait rather than a state-dependent phenomenon given the limited influence of anxiety- and depression-like symptoms and the observed high relative stability (de Timary et al., 2008). Anxiety- and depression-like symptoms were measured with the STAI and BDI. However, no data were available to examine differences in absolute and relative stability between low, moderate, and high alexithymic patients, rendering it impossible to detect a regression to the mean, in contrast to de Haan et al.׳s (2012a) findings, which phenomenon was also suggested by Haviland et al. (1988). In the aforementioned studies on alexithymia during or directly after detoxification, anxiety- and depression-like symptoms were probably SUD (including withdrawal) induced. However, no investigation had been reported on whether these anxiety- and depression-like symptoms derived partly from anxiety and depressive disorders independent of SUD. Neither was investigated, although suggested, if these anxiety- and depression-like symptoms were indeed part of or related to withdrawal symptoms. During a detoxification period, withdrawal symptoms, including stress, anxiety-, and depression-like symptoms, change in severity and may affect the mental state of many patients with SUD. Therefore, a detoxification period appears to be a good opportunity to determine whether alexithymia is a state versus a trait in patients with SUD. A change in the absolute or mean level stability of alexithymia during detoxification indicates the sensitivity of alexithymia to a state, such as withdrawal, that affects the entire patient group. However, patients with SUD can be differentially affected by withdrawal symptoms during detoxification, a fact that can be captured by measures of relative stability. A strong personality characteristic or stable trait, which is best reflected in a high degree of relative stability, should be relatively independent of state factors. A strong relationship with state factors, such as anxiety- or depression-like symptoms, and a low relative stability of alexithymia would support a more state-dependent phenomenon and argue against alexithymia as an autonomous trait-like SUD vulnerability factor (de Timary et al., 2008). This means that addressing alexithymia in the treatment of patients with SUD would not be as necessary if alexithymia were defined primarily as a state-dependent phenomenon that occurs in response to stress, anxiety-, or depression-like symptoms. The treatment could then be focused specifically on the stress, anxiety, and depression components. In case alexithymia is a state-dependent phenomenon independent of other symptoms or disorders, information on the temporary character could be provided to patients to help them overcome this period. However, if alexithymia is an independent, stable personality trait, it would be important to adjust our cognitive behavioral treatment (CBT) interventions to alexithymic patients with SUD with better treatment results as an expected outcome. In CBT, patients are expected to differentiate, name, and describe difficult experiences, such as cravings, withdrawal symptoms, anxiety, and mood states, which is difficult for patients with alexithymia. Given the different results regarding the stability of alexithymia in detoxifying or recently detoxified SUD populations (Haviland et al., 1988, Pinard et al., 1996 and de Timary et al., 2008), as well as the absence of a description of the differences between low, moderate, and high alexithymic patients, we conducted a prospective study of the stability of alexithymia to examine the stability of alexithymia during detoxification while controlling for withdrawal symptoms and personality disorder traits. These controls were included given that withdrawal symptoms are supposed and personality disorder traits have been related to alexithymia in patients with alcoholism (De Rick and Vanheule, 2007 and de Timary et al., 2008). To address our hypothesis that alexithymia is primarily a stable trait in patients with SUD, we formed the following sub-hypotheses: (1) high relative stability of alexithymia scores would be found using the Toronto Alexithymia Scale (TAS-20). (2) Only slight differences in the degree of relative stability would be observed between low, moderate, and high alexithymic patients. This hypothesis was added because of previous findings regarding the differences between these three groups (de Haan et al., 2012a). (3) No change in the mean level of alexithymia scores would be observed (indicating absolute stability). (4) Few differences would be found between low, moderate, and high alexithymic patients with respect to pre–post changes in the mean level of alexithymia scores, indicating a limited regression to the mean. Additionally, to address our hypothesis of high relative and absolute stabilities, we expected to find that (5) baseline alexithymia, rather than state conditions, such as withdrawal symptoms (which are associated with anxiety- and depression-like symptoms), would predict the variance in follow-up alexithymia levels. With respect to our alternative hypothesis that alexithymia is (partially) a state phenomenon, we predicted that (6) the change in alexithymia scores would be related to a change in withdrawal symptoms, including anxiety- and/or depression-like symptoms.