Use of the North American Adult Reading Test to estimate premorbid intellectual function in patients with multiple sclerosis

The North American Adult Reading Test (NART-R) has proven to be a valid mea ns of estimating premorbid intellectual function in a variety of neurologic patient samples. The NART-R was administered to a group of patients with m ultiple sclerosis (MS) varying in course and degree of physical disability and healthy controls as part of an extensive neuropsychological battery exa mining numerous verbal cognitive functions, particularly language. The MS s ample demonstrated significantly worse NART-R performance than did controls which could not be explained by differences in estimated premorbid intelle ctual function. Patients with a chronic-progressive course specifically obt ained significantly lower scores than did controls, whereas there were no d ifferences in the scores obtained by patients with chronic-progressive and relapsing-remitting courses or by patients with a relapsing-remitting cours e and controls. Thus, NART-R performance may not be a valid estimate of bas eline IQ for patients with neurologic disorders with suspected language imp airment.