Deficient intracortical inhibition in drug-naive children with attention-deficit hyperactivity disorder is enhanced by methylphenidate.
In children with attention-deficit hyperactivity disorder (ADHD), motoric hyperactivity is one of the striking abnormalities. Because this symptom might be due to an insufficient motor control, motor system excitability in 18 drug-naive ADHD-children aged 8-12 years was compared to 18 age-matched healthy children using the technique of transcranial magnetic stimulation (TMS). Whereas motor thresholds, cortical silent period, and intracortical facilitation did not differ between the two groups, ADHD-children had significantly reduced intracortical inhibition compared to healthy controls. In all ADHD-children, a second TMS could be started after their first intake of 10 mg methylphenidate. Under this medication, a significant enhancement in intracortical inhibition could be stated. This study provides the first evidence for inhibitory deficits within the motor cortex in ADHD-children and for an enhancement of inhibitory mechanisms in this brain region by methylphenidate.
Moll
G H
GH
Child and Adolescent Psychiatry, University of Göttingen, von-Siebold-Strasse 5, D-37075, Göttingen, Germany.
Heinrich
H
H
Trott
G
G
Wirth
S
S
Rothenberger
A
A
D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy* / Q000503:physiopathology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002648:Child; D004363:Drug Utilization; D005260:Female; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000008:administration & dosage*; D009044:Motor Cortex / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology*; D009433:Neural Inhibition / Q000187:drug effects* / Q000502:physiology*
D000697:Central Nervous System Stimulants; D008774:Methylphenidate