The explicit learning of new names for known objects is improved by dexamphetamine

A randomised, double-blind, placebo-controlled, between subjects study design (N = 37) was used to investigate the effects of dexamphetamine on explicit new name learning. Participants ingested 10 mg of dexamphetamine or placebo daily over 5 consecutive mornings before learning new names for 50 familiar objects plus fillers. The dexamphetamine group recognised and recalled the new names more accurately than the placebo group over the 5 days and 1 month later. Word learning success was not associated with baseline neuropsychological performance, mood, cardiovascular arousal, or sustained attention. These results may have implications for the pharmacological treatment of acquired naming difficulties.