EXECUTIVE FUNCTIONS IN MULTIPLE-SCLEROSIS - AN ANALYSIS OF TEMPORAL ORDERING, SEMANTIC ENCODING, AND PLANNING ABILITIES

Previous studies have consistently demonstrated impairments in concept ual reasoning and set-shifting abilities in patients with multiple scl erosis (MS). Other executive functions have been less frequently exami ned. We compared 44 MS patients and 48 demographically matched control s on a temporal-ordering and semantic-encoding task and on a test of p lanning (Tower of Hanoi). Compared with controls, MS patients experien ced deficient semantic encoding and planning but unimpaired temporal-o rder memory. For both tasks, post hoc analyses indicated that chronic- progressive MS patients contributed most to the group differences. A c ombination of poor planning and slowed information-processing speed wa s hypothesized to have contributed to MS patients' impaired Tower of H anoi performance. Further research is needed to explore the possible r elationship between semantic-encoding and planning deficits in MS and social and occupational disabilities.