A Twin Study of Alexithymia

Abstract

Background: Factors contributing to the development of alexithymia and the nature of alexithymia’s relation with trait negative and positive affectivity are unclear. In this study, a twin approach was used to examine the degree of genetic and environmental contributions to the different facets of alexithymia, and the nature of their relations to trait negative and positive affectivity. Method: Forty-five monozygotic and 32 same-sex dizygotic twin pairs completed the Toronto Alexithymia Scale-20, the Eysenck Personality Inventory, and a zygosity questionnaire. Results: Model fitting analyses indicated that familial influences contributed significantly to all three facets of alexithymia. Parameter estimates and intraclass correlations suggested, though could not confirm, that it was shared environmental factors that contributed to difficulty identifying and communicating emotions (ID and COM), but shared genetic factors that contributed to externally oriented thinking (EOT). Between-twin cross-trait twin analyses revealed strong correlations between ID and neuroticism, and between COM and extraversion, and suggested that it is shared familial influences which account for these associations. Conclusions: The results of this study indicate that: (a) the different facets of alexithymia are influenced by familial factors; (b) the previously noted associations between ID and COM and trait affectivity are not merely methodological artifacts; and (c) the associations between ID and COM and trait affectivity are influenced by familial factors. The results also suggest that ID and COM are largely influenced by shared environmental factors, but that EOT is influenced by genetic factors.

A Behavioral-Genetic Study of Alexithymia and its Relationships with Trait Emotional Intelligence

“…Jorgensen et al's (2007) large BG study of alexithymia also reported similar results. Although there are some reasons why it might be plausible for shared environmental factors to contribute to individual differences in alexithymia -for example, as noted by Valera and Berenbaum (2001), childhood family factors Note: TAS-20 = Toronto Alexithymia Scale; MZ = monozygotic; DZ = dizygotic; DIF = difficulty identifying feelings; DDF = difficulty describing feelings; EOT = externally oriented thinking. a 2 = additive genetic effects; e 2 = non-shared environmental effects; 95% CI = 95% confidence interval.…”

“…Using the TAS, Valera and Berenbaum (2001) conducted a small (77 twin pairs in total; 45 MZ and 32 DZ pairs) adult twin study to examine the influence of genetic and environmental factors on the three facets of alexithymia. Results demonstrated that EOT is strongly influenced by genetic factors, but that DIF and DDF are influenced by shared environmental factors.…”

Temporal Stability of Alexithymia Over a Five-Year Period in Outpatients with Major Depression

“…It did not change even if the depressive symptoms alleviated. One potential explanation is that the three factors of alexithymia have different origins in depressed patients, as presented recently [23]. Also other biological explanations, like interhemispheric transfer or right hemispheric specialisation, for personality construct of alexithymia, have to be empirically studied [24].…”

Circadian Blood Pressure Patterns and Life Stress

“…A hypothesis that has been frequently formulated in the literature [9]is that hypertensive patients display difficulties in expressing their emotions (including tension and irritability). In psychosomatic research, these difficulties have often been subsumed under the rubric of alexithymia [33, 34, 35, 36, 37, 38]. In the setting of stressful life circumstances, this may lead to increased sympathetic activation [39]and anxiety sensitivity [40].…”