Picture and motor sequencing in multiple sclerosis

Abstract

Previous studies consistently report that patients with multiple sclerosis (MS) perform poorly on the Picture Arrangement subtest of the Wechsler Intelligence test. Although this finding implies that MS causes difficulties in cognitive sequencing, the Picture Arrangement test taps many cognitive abilities in addition to sequencing, and the reported deficits by MS patients could reflect difficulties in other skills such as information processing speed or visual acuity and scanning. To circumvent some of these interpretive problems, we used an untimed test of sequencing that required arranging relatively large drawings of familiar scenarios. The MS patients were impaired on this picture sequencing test, but they performed normally on the Luria three-step test of motor sequencing. Correlational analyses showed that picture and motor sequencing were highly correlated, and that performance on both sequencing tests was related to performance on a global mental status exam, the Wisconsin Card Sorting Test and Benton's Facial Recognition Test, but not to upper limb speed and dexterity. These findings demonstrate a relatively specific deficit in cognitive sequencing by MS patients, that can be partially dissociated from impairment in performing simple motor acts.