Alexithymia or general psychological distress? Discriminant validity of the Toronto Alexithymia Scale and the Perth Alexithymia Questionnaire.

Background: Alexithymia is an important transdiagnostic risk factor for emotion-based psychopathologies. However, it remains unclear whether alexithymia questionnaires actually measure alexithymia, or whether they measure emotional distress. Our aim here was to address this discriminant validity concern via exploratory factor analysis (EFA) of the 20-item Toronto Alexithymia Scale (TAS-20) and the Perth Alexithymia Questionnaire (PAQ).

Method: United States general community adults (N = 508) completed the TAS-20, PAQ, and the Depression Anxiety Stress Scales-21 (DASS-21). EFA was used to examine the latent dimensions underlying these measures' scores.

Results: Our EFA extracted two higher-order factors, an "alexithymia" factor and a "general distress" factor (i.e., depression, anxiety, stress). All PAQ scores loaded cleanly on the alexithymia factor, with no cross-loadings on the distress factor. However, for the TAS-20, Difficulty Identifying Feelings (DIF) facet scores cross-loaded highly on the distress factor.

Limitations: Our sample consisted of general community adults; future work in clinical settings will be useful.

Conclusions: Our data indicate that the PAQ has good discriminant validity. However, the TAS-20 appears to have significant discriminant validity problems, in that much of the variance in its DIF facet reflects people's current levels of distress, rather than alexithymia. The TAS-20, which has traditionally been the most widely used alexithymia questionnaire, may therefore not be the optimal alexithymia tool. Our findings add to the body of evidence supporting the validity and utility of the PAQ and suggest that, moving forward, it is a superior option to the TAS-20 for alexithymia assessments.