Adaptation of thought and language disorder scale into turkish and the relation of formal thought disorder with illness severity, cognitive functions, global and social functioning and quality of life in patients with schizophrenia

Mutlu E. Adaptation of Thought and Language Disorder Scale into Turkish and The Relation of Formal Thought Disorder with Illness Severity, Cognitive Functions, Global and Social Functioning and Quality of Life in Patients with Schizophrenia. Hacettepe University Faculty of Medicine, Department of Psychiatry, Dissertation Thesis, Ankara, 2018. Formal thought disorders (FTDs) are considered mainly to be a core feature of schizophrenia. This study aims to analyze the validity and reliability of the Turkish version of "Thought and Language Disorder Scale (TALD)", to detect how FTDs differentiate in different psychiatric diagnoses and finally to study the relation between FTDs and sociodemographic and clinical characteristics, illness severity, cognitive functions, global, social functioning and quality of life in patients diagnosed with schizophrenia. Thought and Language Disorder Scale (TALD) was translated and 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, major depression N=24) and 35 were healty controls. Sociodemographic characteristics were assessed in all participants. Present and past clinical features of patients were assessed through a detailed form, and Positive and Negative Syndrome Scale (PANSS), Hamilton Depression Rating Scale (HAMD), Young Mania Rating Scale (YMRS), Clinical Global Impression Scale (CGI) were administered to detect illness severity. In addition, schizophrenia patients' cognitive functions were investigated using a neuropsychological test battery. Functioning Assessment Short Test (FAST) and the Social Functioning Scale (SFS) were administered to assess global and social functioning, World Health Organization Quality of Life Instrument Short Forum (WHOQOL-BREF) was administered to assess quality of life in schizophrenia patients. The principle 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. These four dimensions were in line with the original TALD factorial structure, and it was concluded that the TALD-TR shows strong construct validity. The crohnbach α values of the factors were found to be 0.91, 0.78, 0.76, 0.53 respectively, in accordance with the original validity study. Intraclass correlation coefficient was 0.95, indicating high interrater reliability. The correlation analyses with TALD and PANSS showed that there are positive correlations between the TALD total score and the PANSS total and subscale scores. 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. Partial correlation analyses, controlling for age and duration of education, showed that the OP dimension was associated with a deficit in executive functions and that the ON dimension was associated with impairment in working memory, category (semantic) verbal fluency, executive functions, abstract thinking and response inhibition. Although FTD was correlated positively with deficits in social, interpersonal and occupational functioning, no relation was detected between FTD and self-reported quality of life. In conclusion, the Turkish version of TALD is a valid and reliable tool with good psychometric properties. The results of this study suggest that FTDs are related with higher illness severity and more impairments in cognitive functions (especially executive functions), general and social functioning in patients with schizophrenia. As thought process disorders in schizophrenia should be investigated in more detail, they should also be considered as one of the main treatment goals, and further research on their pathogenesis should be conducted with priority. Key words: Thought disorder, schizophrenia, cognitive functions, functioning, quality of life