Working memory impairment among persons with chronic progressive multiple sclerosis.

We examined short-term memory (STM) among a group of 23 definite, chronic progressive multiple sclerosis (MS) patients, all of whom had experienced recent significant disease activity, and a control group matched closely on age and education. MS patients were impaired, relative to controls, on the majority of the measures used. Although there were no significant differences between groups on the Mini Mental State Examination, patients performed more poorly on digits forward and backward, the Brown-Peterson test, and the logical memory scale of the Revised Wechsler Memory Scale (both immediate and delayed). Performance on tests sensitive to central processing capacity was significantly correlated with measures of STM. Working memory was significantly impaired in this sample of chronic progressive MS patients. In conjunction with previous research showing deficient information processing and prefrontal dysfunction among this population, the findings suggest that an impairment of central information processing may be a fundamental aspect of the mnestic and cognitive decline observed in many chronic progressive MS patients.