The Turkish adaptation, validity, and reliability of the internal states scale

Maçkalı, Zeynep (Arel Author) (reprint author)Introduction: The Internal State Scale (ISS) was developed to simultaneously assess manic and depressive symptoms in bipolar disorder. In the present study, the validity and reliability of the Turkish version of ISS (ISS-TR) were examined. The present study aimed to present the psychometric properties of this scale. Methods: The sample consisted of 200 outpatients with bipolar disorder and 49 healthy controls. Participants completed the Turkish Internal State Scale (ISS-TR), the Brief Psychiatric Rating Scale (BPRS), the Hamilton Depression Rating Scale (HDRS), and the Young Mania Rating Scale (YMRS). Results: Reliability analyses revealed that the Cronbach alfa coefficient of ISS was 0.88 for the whole sample. Item-total correlations ranged from 0.15 to 0.78. Two factors emerged as a result of factor analysis: “mania” and “depression-well-being.” Test–retest correlations were determined for the mania subscale as r=0.654, p<0.01 and for the depression-well-being subscale as r=0.356, p