Dysarthria predicts poorer performance on cognitive tasks requiring a speeded oral response in an MS population.

Dysarthria is a common symptom of multiple sclerosis (MS). To examine its impact on tests requiring speeded oral responses, 97 MS patients and 27 controls were administered the Controlled Oral Word Association Test, the Visual Elevator (VE), and the Symbol Digit Modalities Test (SDMT). Regression analyses revealed that dysarthria significantly predicted patient performance on the SDMT and VE. When dysarthria was controlled for, patient status no longer accounted for a significant amount of the variance in predicting VE performance; the contribution of patient status to SDMT variance was also reduced substantially, though still statistically significant. These results suggest that the poor performance of MS patients on some tasks that require oral responses is partially due to dysarthria.