Abstract: Background: The diagnosis of mania largely depends on the quality of information the physician is provided with. Often, the patient cannot give an accurate account of the symptom development and thus information from relatives and friends is required. No systematic rating instrument is available, however, to facilitate this.Objective: In this study, the psychometric properties of the 49-item Observer-Rated Scale for Mania (ORSM) are reported.Methods: The scale was used in 113...