Elsevier

NeuroImage

Volume 32, Issue 3, September 2006, Pages 1472-1482
NeuroImage

Impaired self-awareness and theory of mind: An fMRI study of mentalizing in alexithymia

https://doi.org/10.1016/j.neuroimage.2006.04.186Get rights and content

Abstract

Alexithymic individuals have difficulty in recognizing and describing emotions in themselves. We investigated the neuronal basis of mentalizing in alexithymia to determine whether there is a common neuronal substrate associated with knowing the mental states of the self and others. Individuals high in alexithymia (n = 16) and low in alexithymia (n = 14) were selected from a pool of 310 college students using a combination of the Toronto Alexithymia Scale (TAS-20) and the Structured Interview version of the Beth Israel Questionnaire (SIBIQ). We compared the two groups on psychological measures, including ratings of mentalizing and the Interpersonal Reactivity Index (IRI), and regional brain activation using functional magnetic resonance imaging (fMRI) during a mentalizing animation task. The results for both groups showed activation in regions associated with mentalizing: medial prefrontal cortices (MPFC), temporo-parietal junctions (TPJ), and the temporal pole (TP). Alexithymics had lower mentalizing and IRI perspective-taking scores and less activation in the right MPFC. Activity in the MPFC was positively correlated with the mentalizing score and the IRI perspective-taking score. Although there were no group differences in cerebral activity in the TPJ and the TP, the activity in the right TP had a positive correlation with mentalizing and IRI personal distress scores. These results suggest that alexithymic individuals have an impairment in mentalizing associated with an inability to take the perspective of others. Thus, the skills involved in comprehending the self and others are inter-related and play an important role in emotion regulation.

Introduction

Alexithymia is a disturbance in both affective and cognitive functioning characterized by difficulty in describing or recognizing the emotions of the self. Alexithymia was originally described by Sifneos (1972) in patients with psychosomatic disorders. Subsequently, alexithymia was regarded as an impairment of emotion self-regulation that is found in a broad range of physical and psychiatric disorders (e.g., alcoholism, drug addiction, and post traumatic stress disorders; see Taylor et al., 1997). At the present time, alexithymia is not considered a discrete disorder but rather a personality characteristic that is expressed with variable intensity in the general population.

Although alexithymia refers to a deficit in emotional self-awareness, Bydlowski et al. (2005) reported that high alexithymic patients with eating disorders showed impairment in the ability to describe the emotional experiences of others in hypothetical situations. Thus, emotional self-awareness seems to be closely related to sensitivity to the emotions of others. Furthermore, the capacity to differentiate the emotions of the self from those of another person in a given context appears to be crucial for managing a variety of emotional states (Bydlowski et al., 2005). Lane and Schwartz (1987) noted that as the level of emotional awareness increases, the differentiation of self from other increases. In the absence of such differentiation, emotions remain global and undifferentiated, leading to a relative inability to use one's own emotions to guide the selection of adaptive behavior.

Understanding that others have beliefs, desires, and intentions different from the self is a cognitive skill known as “Theory of mind” (ToM) or ‘mentalizing’ (Frith and Frith, 2003). Autistic spectrum disorders, including Asperger's syndrome, are characterized by an impairment of ToM (Baron-Cohen et al., 1985, Baron-Cohen et al., 1997). Asperger's syndrome is associated with high alexithymia scores (Berthoz and Hill, 2005, Frith, 2004, Hill et al., 2004). This suggests that the ability to describe the mental states of self and other is related. Alexithymia was also associated with impairment in the ability to identify emotions from facial expressions (Pandey and Mandal, 1997, Parker et al., 2005, Lane et al., 1996). Alexithymia has been related to certain psychiatric disorders characterized by a deficit in the ability to know what others are thinking and feeling or a lack of empathy, for example, schizophrenia (Cedro et al., 2001, Maggini and Raballo, 2004a, Maggini and Raballo, 2004b, Stanghellini and Ricca, 1995, Todarello et al., 2005, van 't Wout et al., 2004), and borderline (Guttman and Laporte, 2002) and psychopathic personality disorders (Haviland et al., 2004). Thus, disorders characterized by ToM impairment are also associated with alexithymia.

It would therefore appear likely that individuals with alexithymia have an impaired ability to know the minds of others, which might contribute to difficulties in emotion regulation and interpersonal relations. However, the relation between alexithymia and mentalizing has only been sparsely investigated (for example, see Wastell and Taylor, 2002), and its neural basis remains to be examined.

We therefore investigated neuronal activation in individuals with high and low alexithymia during a ToM task using functional magnetic resonance imaging (fMRI). We hypothesized that alexithymia would be associated with decreased neuronal activity in the medial prefrontal cortex (MPFC), the temporo-parietal junction (TPJ), and the temporal pole (TP), a neuronal activity pattern characteristic of subjects who are known to have a deficit in the capacity for mentalizing, such as patients with Asperger's syndrome (Castelli et al., 2002, Frith and Frith, 2003).

Section snippets

Subjects

We screened 310 college students (105 males and 205 females) for alexithymia using a self-administrated questionnaire, TAS-20 (Taylor et al., 2003, Komaki et al., 2003). Individuals with high or low TAS-20 total scores (n = 20, score > 60 and n = 18, score < 39, respectively) were selected to obtain two groups that were maximally divergent on alexithymia. This yielded 38 volunteers (30 females, 8 males; 19 to 22 years of age, mean age = 20.4 years, SD = 0.938). All subjects gave written

Behavioral measures

There was no difference between the groups in the ratio of male to female subjects (13 alexithymia females to 3 alexithymia males and 12 non-alexithymia females to 2 non-alexithymia males; χ2 = 0.168, Fisher's Exact probability = 1.00, two tailed), so scores for men and women were combined (see Table 2). The alexithymia group scored significantly lower than the non-alexithymia group on ToM intentionality, appropriateness, IRI perspective taking and empathic concern, and scored significantly

Discussion

Our study demonstrates differences between individuals in behavioral and neural responses to a mentalizing task as a function of alexithymia. Alexithymia, a disturbance in self-awareness, was associated with impairment in mentalizing and the related empathic ability of perspective taking, the ability to see things from the point of view of another person. Neural activity in the medial prefrontal cortex was decreased in alexithymics, and activity in the same region was closely related to

Conclusion

Our findings demonstrate that alexithymia, a deficit in the ability to identify and describe the feeling states of the self, is related to impaired mentalizing (comprehending the mind of others), which in turn is associated with hypoactivity in the MPFC. The deficit in mentalizing that we observed is associated with impairment in the higher cognitive ability to take a perspective different from the self, a skill that may be essential for the comprehension of the mental states of both self and

Acknowledgments

This study was supported by the Research Grant (17A-3) for Nervous and Mental Disorders from the Ministry of Health, Labour and Welfare, Japan.

We thank Dr. Uta Frith for her generous donation of the animation to the project.

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