The effects of 0.3 mg/kg and 1.0 mg/kg of methylphenidate on the overt behavior and academic functioning of 12 children with ADDH are reported from the Department of Psychiatry Research, Hospital For Sick Children, Toronto, Ontario, Canada. A double blind placebo control crossover design was used and each child was tested four times in each drug condition. Methylphenidate enhanced academic functioning by increasing accurate productivity on academic tasks, as well as improving overt behavior. All 12 children were able to complete more work at all levels of the arithmetic task and the letter task without sacrificing accuracy. The majority showed more than a 25% increase in the number of problems completed correctly compared with placebo level performance. The beneficial effects on academic performance did not vary with dosage or task complexity. Behavioral and academic improvements produced by a dose of 0.3 mg/kg in the morning were no longer evident in the afternoon, but a morning dose of 1.0 mg/kg produced behavioral improvements that were clinically and statistically present in the afternoon although academic improvements had disappeared. An increase in pulse and blood pressure was observed one hour following 1.0 mg/kg methylphenidate. [1]

COMMENT. Sprague and Sleator reported differences in dose effects on learning and social behavior following treatment with methylphenidate [2]; cognitive performance was maximized at a dosage of 0.3 mg/kg and was impaired by dosages of 1.0 mg/kg or higher. The present study indicated that the larger dosage resulted in a leveling of academic performance and not a decline. The authors admit that the high dose may have enabled the children to sit still and be quiet thereby facilitating their cognitive functioning. In attempting to determine an optimal dose for each child it is essential that the physician notes the dose response and timed course of action on academic, cognitive, and behavioral performance.