title: Relationship and differential validity of alexithymia and depression: a comparison of the Toronto Alexithymia and Self-Rating Depression Scales.
abstract: Theoretically, the constructs of alexithymia and depression share many common characteristics. Empirically moderate correlations between measures of alexithymia and depression have been found, hence it has been argued that the Toronto Alexithymia Scale (TAS) may be, at least in some part, just another measure for depression. The purpose of this study was to evaluate the construct validity of alexithymia and to analyze the relationship between alexithymia and depression. Exploratory and confirmatory factor analyses were conducted on the combined items of the TAS-20 and the Self-Rating Depression Scale (SDS) in a psychosomatic and alcoholic inpatient sample (n = 199) and a sample of normal adults (controls, n = 174). The exploratory factor analysis in the patient sample yielded a 4-factor structure. Within each factor there was no overlap between the items of the TAS-20 and the SDS. Two factors were comprised of items of the TAS-20 and two factors consisted of items of the SDS. This 4-factor model also showed an acceptable fit for the data of the normal sample in a confirmatory factor analysis. Moderate correlations between the TAS- 20 and SDS total scores and some factors were found. Both instruments, the TAS-20 and the SDS, seem to measure distinct constructs and are not just different measures for the same underlying construct. This provides support for the differential validity of the alexithymia and depression constructs and is in accordance with previous findings.
authors.affiliation: Institute of Psychology I, University of Würzburg, Marcusstrasse 9-11, D-97070 Würzburg, Germany. j.mueller@psychologie.uni-wuerzburg.de
authors.forename: Jochen
authors.initials: J
authors.lastname: Müller
authors.forename: Markus
authors.initials: M
authors.lastname: Bühner
authors.forename: Heiner
authors.initials: H
authors.lastname: Ellgring
mesh_terms: D000328:Adult; D000342:Affective Symptoms / Q000175:diagnosis* / Q000453:epidemiology; D000368:Aged; D003863:Depression / Q000175:diagnosis* / Q000453:epidemiology; D003937:Diagnosis, Differential; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D015203:Reproducibility of Results; D012647:Self-Assessment; D011795:Surveys and Questionnaires