Deficient intracortical inhibition in drug-naive children with attention-deficit hyperactivity disorder is enhanced by methylphenidate
Moll GH, Heinrich H, Trott G, Wirth S, Rothenberger A.
Neurosci Lett. 2000 Apr 21;284(1-2):121-5.

Child and Adolescent Psychiatry, University of Gottingen, von-Siebold-Strasse 5, D-37075, Gottingen, Germany.

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.




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