Methylphenidate does not modify the impact of response frequency or stimulus sequence on performance and event-related potentials of children with attention deficit hyperactivity disorder.
Twenty-six children with attention deficit/hyperactivity disorder (ADHD) participated in a double-blind trial consisting of 2 consecutive weeks each of placebo and methylphenidate (M = 26.92 mg/day = 0.78 mg/kg/day). As expected, stimulant therapy resulted in moderate weight loss, increased somatic complaints, and teacher and parent reports of reduced inattentiveness, aggression, and oppositionality. In both phases of the trial, patients were tested in a choice reaction time task assessing two aspects of the task that presumably affect response selection: response frequency (ratio of targets/nontargets = 25/75 vs. 50/50) and stimulus sequence (alternations vs. repetitions). Both manipulations yielded expected results on performance and event-related potentials (ERPs). Stimulant treatment increased accuracy and speed among younger children and curtailed variability of reaction time for the sample as a whole. However, methylphenidate did not affect ERPs. In combination, the results imply that the enhancement of performance by methylphenidate does not involve the demands of response selection examined in this study.
Pine Rest Northwest Clinic, Grand Rapids, Michigan 49504, USA.
J A
JA
Smithee
R
R
Klorman
J T
JT
Brumaghim
A D
AD
Borgstedt
D001143:Arousal / Q000187:drug effects*; D001288:Attention / Q000187:drug effects; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy*; D000697:Central Nervous System Stimulants / Q000009:adverse effects / Q000627:therapeutic use*; D002540:Cerebral Cortex / Q000187:drug effects; D002648:Child; D004193:Discrimination Learning / Q000187:drug effects; D004569:Electroencephalography / Q000187:drug effects; D005071:Evoked Potentials / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000009:adverse effects / Q000627:therapeutic use*; D010364:Pattern Recognition, Visual / Q000187:drug effects; D011597:Psychomotor Performance / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects*
D000697:Central Nervous System Stimulants; D008774:Methylphenidate