Attention in multiple sclerosis: correlates of impairment on the WAIS-R Digit Span Test

To re-examine the status of attention in multiple sclerosis (MS) 109 patients with clinically definite MS were administered the WAIS-R Digit Span (DS) and a battery of other neuropsychological (NP) tests of problem solving, abstraction, short-term memory (STM), long-term memory and verbal fluency. Compared to a group of controls of equivalent age and education, the MS patients were impaired on DS and all of the other NP tests. Although the magnitude of the patients' overall DS deficits was comparable for forward and backward spans, the patterns of correlations of NP tests with performance on the forward and backward DS tests were distinctly different. These results can be accounted for by postulating that MS patients suffer from a mild generalized difficulty in maintaining concentration and a more specific impairment in regulatory systems that allocate limited attentional resources among multiple stimulus inputs or tasks.