RECENT PRESENTATIONS

Chellaramani, R., Pellouchoud, E., Smith, M.E., Gevins, A. (2002). Effect of stimulant medication on attention and working memory in children with ADHD. Cognitive Neuroscience Society Ninth Annual Meeting. April, San Francisco.

ABSTRACT

Attention-deficit/hyperactivity disorder (ADHD) in children is characterized by poor concentration, inattentiveness, and a deficit in behavioral inhibition that may result in an inability to sustain attention during working memory (WM) tasks. Children diagnosed with ADHD are often treated with stimulant medications that are thought to stifle hyperactivity, enhance concentration, and perhaps improve the child's ability to sustain activation of task-relevant representations. In this study fourteen children with ADHD performed two difficulty levels of an "n-back" WM task both on and off stimulant medication. EEG data were collected during the WM task and under resting conditions. Average behavioral and electrophysiological measurements across the two test sessions indicated that these measures differed as a function of task load in a manner similar to that observed in healthy adults. Specifically reaction time increased, accuracy decreased, and the EEG alpha rhythm during task performance deceased as task difficulty increased. On average performance accuracy was higher and reaction times were faster in the medicated condition, but these effects did not reach significance. Medication decreased theta band power and increased P300 ERP amplitude in low load task condition. These modest group effects mask relatively large effects on different behavioral and EEG measures in individual subjects. Such high between-subject variability might reflect variations in abilities, symptoms, and treatments in children with ADHD. Such effects are also consistent with the notion that children with ADHD differ in the degree to which they respond positively to stimulant medication. Supported by NICHD and NIMH.