Cognitive impairment in patients with multiple sclerosis and mild physical disability.

Forty mildly disabled and clinically stable patients with multiple sclerosis (MS), representative of the corresponding population in Northern Holland, with disability Status Scale scores evenly distributed within the 1 to 4 range, were compared with 40 age-, sex-, and education-matched normal controls on a battery of neuropsychological tests. Apart from impairments in perceptual-motor functioning, generally mild deficiencies in intelligence and, specifically, in memory were displayed in the MS group. Attentional processes appeared uncompromised. Increasing fatigue during testing could not account for poor performance. The memory deficits could be attributed to poor initial learning, although there was also evidence suggesting that accelerated forgetting of what had been learned may appear with the progression of MS. Seven patients (17.5%), as compared with none of the controls, were classified by blind clinical judgement of test performance as definitely impaired.