Objective: The Scale for the Assessment of Thought, Language and Communication (TLC) is a widely used instrument for the assessment of formal thought disorder. TLC disorders were initially conceptualized as having only two underlying dimensions, a negative and a positive one. But studies of the factorial structure of the TLC have not provided confirmation for the positive-versus-negative distinction. The aim of the present study was to assess the factorial structure of the Greek translation of the TLC.
Method: Subjects were 103 patients (69 male, 34 female) with psychotic disorders randomly recruited from both inpatient and outpatient facilities. The TLC was assessed by two raters based on a 20 min clinical interview.
Results: Principal component analysis with varimax rotation yielded a three-factor structure; the three factors consisted off items reflecting (i) disorganization of speech; (ii) peculiarities of speech; and (iii) verbosity. The disorganization factor could be further divided into two dimensions reflecting disturbances in the flow of ideas and in the structure of speech.
Conclusion: The investigation of the factorial structure of the Greek translation of the TLC scale found no support for the positive-versus-negative distinction of TLC disorders. Three factors (disorganization, speech peculiarities, and verbal productivity) were found to underlie the variance of the scale.