The assessment of alexithymia: a critical review of the literature and a psychometric study of the Toronto Alexithymia Scale-20.
OBJECTIVE
The objectives were to give an overview of studies on the validity of the Toronto Alexithymia Scale (TAS-20) and to present data regarding the validity of the TAS-20.


METHODS
The literature on the psychometric properties of the TAS-20 was reviewed and a study was conducted of its psychometric properties in a sample of students and a sample of psychiatric outpatients using a statistical method allowing identification of a stable factor structure.


RESULTS
The review revealed that the majority of studies on the TAS-20 were conducted with nonpatient samples. The factorial validity and reliability of the dimensions 'identifying feelings' (DIF) and 'describing feelings' (DDF) could be replicated in many of these studies. However, in practically all studies the dimension 'externally oriented thinking' (EOT) appears to be unreliable. In addition, the presupposed fantasy aspect of the alexithymia construct is not included in the TAS-20. Although many studies were conducted on the construct validity of the TAS-20, no studies have been published on its criterion validity. Some studies show a different factor structure to exist in patient samples. This was confirmed in our own study in which the dimensions 'identifying feelings' and 'describing feelings' collapsed into one single subscale. As in other studies, the reliability of the dimension 'EOT' was low.


CONCLUSIONS
The TAS-20 has some important shortcomings with respect to validity and reliability. For the assessment of alexithymia in empirical research, it is recommended to use the TAS-20 in combination with other instruments. We do not recommend the TAS-20 to be used in clinical practice.
Kooiman
C G
CG
Department of Psychiatry, Leiden University Medical Center, The Netherlands. cgkooiman@lumc.nl
Spinhoven
P
P
Trijsburg
R W
RW
D000342:Affective Symptoms / Q000145:classification / Q000175:diagnosis / Q000523:psychology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics; D012680:Sensitivity and Specificity