Effects of methylphenidate on attention in children with moderate mental retardation

Abstract

Six children with moderate mental retardation participated in a double-blind, placebo-controlled, crossover study of the effects of methylphenidate on performance on simultaneous two-choice discrimination learning problems, a sustained attention task, and classroom activity. Dependent measures were compared for: (1) % correct on discrimination learning problems; (2) sensitivity and bias on a sustained attention task; and (3) time on-task during classroom activities. Only the sustained attention task and the classroom measure showed a clear effect of methylphenidate. Two children performed better on the drug, one performed better on the placebo, and three showed no systematic effects. The two children who responded favorably to the drug spent more time on task in the classroom, showed higher sensitivity on the sustained attention task and adopted a more efficient, less conservative, criterion on this test. These results are inconsistent with the idea that methylphenidate improves the manageability of some children by decreasing behavior levels, in general, or by reducing impulsivity, in particular. Methylphenidate increased response output and the degree of environmental control of this output. The improvement in sensitivity demonstrates an attentional effect that cannot, in this case, be confounded by response bias factors.