Methylphenidate and memory: dissociated effects in hyperactive children.

Fourteen children with Attention Deficit Disorder with Hyperactivity (ADD + H) were administered the psychostimulant methylphenidate in a double-blind, placebo-controlled, crossover study. Subjects were evaluated on a well-validated measure of verbal memory and learning with an experimental design comprised of four conditions: placebo and active drug at three doses. Positive memory effects were found in the drug conditions. Significant dose-response relationships were found, indicating enhanced learning from placebo to low to medium to high dose. However, there was a differential drug effect on the memory task; methylphenidate selectively enhanced storage and retrieval mechanisms without affecting immediate acquisition.