The effects of methylphenidate (MPH), in 2 doses (0.3 and 0.8 mg/kg), on an attentional continuous performance task (CPT) and on a nonverbal learning task presented in two levels of difficulty, were evaluated in 23 children, aged 7 to 11 years, with attention deficit hyperactivity disorder treated at the Scottish Rite Children’s Medical Center, Atlanta, GA. Attention task performance by the group was improved with low-dose MPH compared to placebo; CPT commission errors were reduced, while omission errors were not affected. On nonverbal learning and memory tasks, the easy level of task performance was improved equally with either dose of MPH, whereas the hard task was performed better with the high dose. 
COMMENT. Low dose methylphenidate may control impulsivity in ADHD children, whereas high doses may be required to improve retention and recall of complex nonverbal information. Cognitive function as well as behavior may be sensitive to stimulant medication, but doses must be individualized and titrated for each patient. Results of group responses may not be applied to all individuals.
Body mass is not predictive of clinical response to MPH, according to a study of 76 children with ADHD receiving doses of 5 to 20 mg at the University of Hawaii, Honolulu, HI . Dose-response does not differ in children of varying body mass, and the dose of MPH should not be calculated on the basis of body weight.