BACKGROUND: Existing metrics of patient-reported cognitive difficulties in multiple sclerosis (MS) are lengthy, lack psychometric rigor, and/or fail to query prevalent expressive language deficits. OBJECTIVE: Develop a brief psychometrically robust metric of patient-reported cognitive deficits that includes language items
the Multiple Sclerosis Cognitive Scale (MSCS). METHOD: Exploratory factor analysis (EFA) was conducted on 20 Perceived Deficits Questionnaire (PDQ) items plus five newly developed language questions in a large MS sample and matched respondents without neurologic disease. Independent confirmatory principal components analysis (PCA) assessed EFA factor structure. Reliability of the new scale and subscales, and relationships with objective cognitive impairment and cognitive change, were assessed. RESULTS: EFA in patients ( CONCLUSION: The brief MSCS is a psychometrically robust, reliable, and valid metric of patient-reported cognitive deficits in MS that holds promise for improving assessment of MS cognitive dysfunction.