Examination of formal thought disorder and its clinical correlates with the Turkish Version of the Thought and Language Disorder Scale (TALD-TR) in schizophrenia

Abstract

Background: Formal thought disorder (FTD) is considered to be a fundamental feature of schizophrenia. This study aims to analyze psychometric properties of the Turkish version of “Thought and Language Disorder Scale (TALD)” and investigate the relationship between FTD and various clinical characteristics in patients with schizophrenia. Methods: TALD was adapted into Turkish and applied to a total of 149 participants of which 114 had DSM-5 psychiatric diagnoses (schizophrenia N = 70, mania N = 20, depression N = 24) and 35 were healthy controls. Positive and Negative Syndrome Scale (PANSS), Hamilton Depression Rating Scale, Young Mania Rating Scale, and Clinical Global Impression were administered to detect illness severity. Results: The principal component analyses revealed that the Turkish version of TALD (TALD-TR) consisted of four factors including the Objective Positive (OP), Subjective Negative (SN), Objective Negative (ON) and Subjective Positive (SP) symptom dimensions which were in line with the original TALD factorial structure. It was concluded that TALD-TR shows strong construct validity and high interrater reliability. The correlation analyses with TALD-TR and PANSS showed that there are positive correlations between the TALD-TR total score and the PANSS total and subscale scores. Each diagnostic group showed the distinct pattern of FTD. The mania group exhibited the highest mean total score in the OP, whereas the schizophrenia group exhibited the highest mean total score in the ON factor. In the schizophrenia group, the severity of FTD correlated positively with duration of illness and negatively with age at onset of illness. Conclusion: Adaptation of TALD into different languages seems to be possible, bringing in an international tool for research on FTD. Keywords: Formal thought disorder, Schizophrenia, Mania, Depression, Language processing