The neuropsychological effects of chronicmethylphenidate on drug-naive boys with attention-deficit/hyperactivity disorder

The reported neuropsychological effects of methylphenidate (MPH) in attention-deficit/hyperactivity disorder (ADHD) are in consistent. The assumed relationships between these neuropsychological effects and clinical efficacy have not been substantiated. Wetherefore investigated the effects of chronic MPH administration on neuropsychological functioning. We conducted a 12-week, placebo-controlled, double-blinded, randomized, crossover trial (MPH .3 and .6 mg/kg/dose andplacebo). Participants were 75 boys aged 7-15 years with ADHD. Neuropsychological performance was assessed with tests taken from theCambridge Neuropsychological Test Automated Battery (CANTAB) battery and a GoNoGo task. ChronicMPHimproved performance (p.001) on aspects of theGoNoGotask (p.02) and on threeCANTABtasks which togethercontributed to a 'recognition memory' component identified through principal components analysis (delayed matching to sample [DMtS],pattern and spatial recognition). There were no effects on other, high or low 'executive demand' tasks (p .05). GoNoGo performanceimprovements were the only neuropsychopharmacological changes associated with clinical response. Poor performance on the DMtS taskwas the sole baseline neuropsychological predictor of clinical response. Chronic MPH predominantly enhanced neuropsychological functioning on 'recognition memory' component tasks withmodest 'executive' demands. Neuropsychological measures offer only modest contributions to the prediction of clinical responses to MPHin ADHD