Effects of methylphenidate on attention and nonverbal learning in children with attention-deficit hyperactivity disorder.

OBJECTIVE: To examine effects of methylphenidate (MPH) doses on attention and learning tasks requiring varying levels of processing in 23 children with attention-deficit hyperactivity disorder.
METHOD: Performance on a continuous performance task (CPT) and two difficulty levels of a nonverbal learning task was evaluated on two doses of MPH (0.3 mg/kg and 0.8 mg/kg) and placebo.
RESULTS: CPT commission errors were significantly reduced with low-dose MPH compared with placebo while omission errors were not medication-sensitive. Performance on nonverbal learning tasks was significantly improved with MPH. On the easy level of the nonverbal learning task performance improved equally well with either dose. On the hard level, performance was significantly better at the high dose compared with placebo; no between-dose differences emerged across learning trials. However, the high dose was superior to low and placebo doses in memory recall trials.
CONCLUSIONS: Impulsivity may be reduced on an attentional task with a low dose of MPH, and a high dose of MPH may optimize retention and recall of complex nonverbal information.