PASAT in detecting cognitive impairment in relapsing-remitting MS

The PASAT, as a part of the Multiple Sclerosis Functional Composite, is used as a sole measure of cognition in multiple sclerosis (MS) clinical trials. In the present study, we evaluated the frequency and characteristics of cognitive impairment among relapsing-remitting MS patients. Using a comprehensive neuropsychological examination as the "golden standard," we assessed PASAT's sensitivity and specificity in MS-related cognitive impairment as well as factors possibly confounding PASAT performance. Forty-five relapsing-remitting MS patients and 48 healthy controls were studied using PASAT and a comprehensive neuropsychological examination. The frequency of cognitive dysfunction among MS patients was 42%. Cognitive impairment in MS was heterogeneous in nature but characterized, especially, by reduced information-processing ability and memory deficits. PASAT's sensitivity for patients' cognitive impairment was 74% and specificity 65%. Misclassification of cognitive impairment seemed to be associated with self-reported nervousness and poor arithmetic skills. Although PASAT offers satisfactory sensitivity in detecting the presence of cognitive impairment, its specificity may be limited by confounding factors.