Cognitive effects of immediate-release methylphenidate in children with attention-deficit/hyperactivity disorder

A growing body of literature has examined the cognitive effects of immediate-release methylphenidate in children with attention-deficit/hyperactivity disorder (ADHD). However, a clear Understanding of the types and magnitude of such effects are difficult to discern from such a large and varied collection Of published reports. This review evaluated a total of 40 relevant placebo-controlled Studies published since Rapport and Kelly's [1993. Psychostimulant effects on learning and cognitive function. In: Matson, J.L.. (Ed.), Handbook of Hyperactivity in Children. Allyn & Bacon, Boston, pp. 97-136] Original review of cognitive effects of methylphenidate in children with ADHD. Of these published studies, 63.5% identified some improvement in cognitive function following methylphenidate treatment. Methylphenidate improved performance on saccadic eye movement, planning/cognitive flexibility, attention/vigilance, and inhibitory control tasks in 83.3%, 71.4%, 70.6%, and 69.7% of studies, respectively. A total 58.3% and 50% Of Studies that evaluated the effect of methylphenidate on tasks of memory and working memory/divided attention, respectively, noted improvement. Variability of findings across Studies may be explained by differential effects of methylphenidate on brain function, intra- and inter-individual variability in medication response, methodological limitations, and problems associated with repeated neuropsychological assessment and metric properties of commonly utilised neuropsychological instruments.. (c) 2006 Elsevier Ltd. All rights reserved.