Influence of stimulant medication and response speed on lateralization of movement-related potentials in attention-deficit/hyperactivity disorder.
BACKGROUND
Hyperactivity is one of the core symptoms in attention deficit hyperactivity disorder (ADHD). However, it remains unclear in which way the motor system itself and its development are affected by the disorder. Movement-related potentials (MRP) can separate different stages of movement execution, from the programming of a movement to motor post-processing and memory traces. Pre-movement MRP are absent or positive during early childhood and display a developmental increase of negativity.


METHODS
We examined the influences of response-speed, an indicator of the level of attention, and stimulant medication on lateralized MRP in 16 children with combined type ADHD compared to 20 matched healthy controls.


RESULTS
We detected a significantly diminished lateralisation of MRP over the pre-motor and primary motor cortex during movement execution (initial motor potential peak, iMP) in patients with ADHD. Fast reactions (indicating increased visuo-motor attention) led to increased lateralized negativity during movement execution only in healthy controls, while in children with ADHD faster reaction times were associated with more positive amplitudes. Even though stimulant medication had some effect on attenuating group differences in lateralized MRP, this effect was insufficient to normalize lateralized iMP amplitudes.


CONCLUSIONS
A reduced focal (lateralized) motor cortex activation during the command to muscle contraction points towards an immature motor system and a maturation delay of the (pre-) motor cortex in children with ADHD. A delayed maturation of the neuronal circuitry, which involves primary motor cortex, may contribute to ADHD pathophysiology.
Section for Clinical Neurophysiology and Multimodal NeuroImaging, Child and Adolscent Psychiatric Hospital of the University of Technology, Dresden, Germany. Stephan.Bender@uniklinikum-dresden.de
Stephan
S
Bender
Franz
F
Resch
Christoph
C
Klein
Tobias
T
Renner
Andreas J
AJ
Fallgatter
Matthias
M
Weisbrod
Marcel
M
Romanos
D000200:Action Potentials; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy / Q000503:physiopathology*; D016022:Case-Control Studies; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002648:Child; D004569:Electroencephalography; D006801:Humans; D008297:Male; D009068:Movement
D000697:Central Nervous System Stimulants