RETRACTED ARTICLE: Improving the measurement of alexithymia in autistic adults: a psychometric investigation and refinement of the twenty-item Toronto Alexithymia Scale

Abstract

Background Alexithymia, a personality trait characterized by difficulties interpreting one’s own emotional states, is commonly elevated in autistic adults, and a growing body of literature suggests that this trait underlies a number of cognitive and emotional differences previously attributed to autism, such as difficulties in facial emotion recognition and reduced empathy. Although questionnaires such as the twenty-item Toronto Alexithymia Scale (TAS-20) are frequently used to measure alexithymia in the autistic population, few studies have attempted to determine the psychometric properties of these questionnaires in autistic adults, including whether differential item functioning (I-DIF) exists between autistic and general population adults. Methods We conducted an in-depth psychometric analysis of the TAS-20 in a large sample of 743 verbal autistic adults recruited from the Simons Foundation SPARK participant pool and 721 general population controls enrolled in a large international psychological study (the Human Penguin Project). The factor structure of the TAS-20 was examined using confirmatory factor analysis, and item response theory was used to further refine the scale based on local model misfit and I-DIF between the groups. Correlations between alexithymia and other clinical outcomes such as autistic traits, anxiety, and quality-of-life were used to assess the nomological validity of the revised alexithymia scale in the SPARK sample. Results The TAS-20 did not exhibit adequate global model fit in either the autistic or general population samples. Empirically driven item reduction was undertaken, resulting in an eight-item unidimensional scale (TAS-8) with sound psychometric properties and practically ignorable I-DIF between diagnostic groups. Correlational analyses indicated that TAS-8 scores meaningfully predict autistic trait levels, anxiety and depression symptoms, and quality of life, even after controlling for trait neuroticism. Limitations Limitations of the current study include a sample of autistic adults that was overwhelmingly female, later-diagnosed, and well-educated; clinical and control groups drawn from different studies with variable measures; and an inability to test several other important psychometric characteristics of the TAS-8, including sensitivity to change and I-DIF across multiple administrations. Conclusions These results indicate the potential of the TAS-8 as a psychometrically robust tool to measure alexithymia in both autistic and non-autistic adults. A free online score calculator has been created to facilitate the use of norm-referenced TAS-8 latent trait scores in research applications (available at http://asdmeasures.shinyapps.io/TAS8_Score).

Investigating the structure of trait rumination in autistic adults: A network analysis

“…These data were collected during winter and spring of 2019 as part of a larger study on repetitive thinking in autistic adults (Project No. RM0030Gotham) and the SPARK participants in the current study overlap partially with those described in previous investigations , 2021a, 2021b. A total of 1012 individuals enrolled in the study, although only 895 completed the three measures analyzed in the current study (RRS, BDI-II, and SRS-2).…”

“…Additional longitudinal studies will be particularly helpful in clarifying the temporal precedence of one symptom over another, which is more suggestive of a potentially beneficial effect of targeted interventions. Second, as noted in previous studies of this cohort Williams & Gotham, 2021a), this sample of autistic adults is overwhelmingly female, highly educated, and later-diagnosed, and thus less representative of the adult autistic population encountered in typical clinical research samples. However, given the high stability of the centrality coefficients and minimal differences in network structure according to either sex or age of diagnosis, it is unlikely that our findings would have differed meaningfully in a sample of earlier-diagnosed male participants.…”

Feasibility, Acceptability and Preliminary Efficacy of Dialectical Behavior Therapy for Autistic Adults without Intellectual Disability: A Mixed Methods Study

“…(GAFS-8; Williams & Gotham, 2021 ) is an 8-item unidimensional scale that measures alexithymia using eight items derived from the Toronto Alexithymia Scale (TAS-20; Bagby et al, 1994 ). The selection of items (TAS-20 items: 1, 2, 6, 9, 11, 12, 13, and 14) has been found to be a reliable measure of alexithymia in autistic adults (Williams & Gotham, 2021 ). The GAFS-8 is the only alexithymia score to be thoroughly validated in the autistic population to date (Williams & Gotham, 2021 ).…”

“…The selection of items (TAS-20 items: 1, 2, 6, 9, 11, 12, 13, and 14) has been found to be a reliable measure of alexithymia in autistic adults (Williams & Gotham, 2021 ). The GAFS-8 is the only alexithymia score to be thoroughly validated in the autistic population to date (Williams & Gotham, 2021 ). As the measure is recent and has not yet been validated in French, we referred to the corresponding items in the French version of the TAS-20 (Loas et al, 1996 ).…”

The Structure of the Toronto Alexithymia Scale (TAS-20): A Meta-Analytic Confirmatory Factor Analysis

“…For example, a 20-item questionnaire might be brief, but still to extensive for large-scale studies that rely on strongly abbreviated versions. The data at hand (i.e., the weighted correlation matrix) might allow compiling a short version of the TAS-20 (see also Williams & Gotham, 2021). Analyzing the meta-analytic results with modern item selection algorithms such as Ant Colony Optimization (Schroeders et al, 2016) several psychometric criteria could be considered simultaneously.…”