Restoration of disturbed intracortical motor inhibition and facilitation in attention deficit hyperactivity disorder children by methylphenidate.
BACKGROUND
Previous investigations using transcranial magnetic stimulation (TMS) have shown that neural inhibitory motor circuits are disturbed in ADHD children. We sought to investigate the influence of methylphenidate (MPH) on inhibitory and facilitatory motor circuits of ADHD children with TMS paired pulse protocols using surplus long interval inter-stimulus intervals (ISI) not investigated so far.


METHODS
Motorcortical modulation was tested with TMS paired pulse protocols employing ISI of 3, 13, 50, 100, 200, and 300 msec in 18 ADHD children before and on treatment with MPH. Clinical improvement by MPH was measured by the Conners score.


RESULTS
Analysis of variance (ANOVA) revealed a significant three-way interaction "Group x Amplitude x ISI," p = .001. Subsequent two-factorial ANOVAs and t-tests showed group specific differences of motor evoked potential (MEP) amplitudes for inhibitory ISIs of 3 and 100 msec, and for facilitatory ISIs of 13 and 50 msec. Compared to controls, an adjustment of these parameters by MPH could be shown. On MPH, a significant bivariate correlation was found between the Conners score reduction and averaged MEP amplitude changes only for inhibitory ISIs (3 and 100 msec).


CONCLUSIONS
In ADHD children, MPH modulates disturbed facilitatory and inhibitory motor circuits, which for the latter is associated with clinical improvement.
Buchmann
Johannes
J
Department of Child and Adolescence Psychiatry and Neurology, Center of Nerve Diseases, University of Rostock, Rostock, Germany. johannes.buchmann@med.uni-rostock.de
Gierow
Wolfgang
W
Weber
Simone
S
Hoeppner
Jacqueline
J
Klauer
Thomas
T
Benecke
Reiner
R
Haessler
Frank
F
Wolters
Alexander
A
D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy* / Q000503:physiopathology*; D016022:Case-Control Studies; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D002648:Child; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use*; D009044:Motor Cortex / Q000187:drug effects / Q000503:physiopathology* / Q000528:radiation effects; D009433:Neural Inhibition / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000379:methods
D000697:Central Nervous System Stimulants; D008774:Methylphenidate