The Effects of Methylphenidate on Neural Substrates Associated with Interference Suppression in Children with ADHD: A Preliminary Study Using Event Related fMRI.
OBJECTIVE
The core deficit of attention deficit hyperactivity disorder (ADHD) is associated with frontal cortex and related circuitry. Children with ADHD and a medication history have shown atypical brain activation in prefrontal and striatal brain regions during cognitive challenge. We investigated two cognitive control operations such as interference suppression (IS) and response inhibition (RI) in children with ADHD. We also assessed the brain functions affected by the methylphenidate (MPH) effect by comparing the blood-oxygen level dependent (BOLD) signals in ADHD children on and off medication.


METHODS
Eight children (9-11 years of age) with combined-type ADHD underwent rapid event-related functional magnetic resonance imaging (fMRI) during performance of a modified flanker task. Two fMRI (3.0 T) scans were conducted with a one week interval-one with MPH treatment and the other without. Functional maps were generated through group averaging and performance-based correlational analyses.


RESULTS
Performances of the two cognitive control operations did not differ significantly between on-MPH and off-MPH status other than the reaction time to incongruent stimuli in ADHD children. In those affected by MPH treatment, an increased activation in the right prefrontal cortex during incongruent task was observed relative to a neutral trial in children with ADHD.


CONCLUSIONS
On the treatment of MPH, the ADHD children exhibited increased activation of the right frontal cortex during interference suppression. This finding suggested that MPH affected the right frontal cortex in ADHD compensating for a reduced level of interference suppression. Future studies will be required to ascertain the MPH effect of cognitive brain regions among large number of children with ADHD.
Lee
Young-Sik
YS
Department of Psychiatry, Chung Ang University College of Medicine, Seoul, Korea.
Han
Doug Hyun
DH
Lee
Jang Han
JH
Choi
Tae Young
TY
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