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Abstract
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The present study investigates the neurophysiological changes induced by methylphenidate (MPH) in children with ADHD by using electroencephalogram (EEG) and functional near-infrared spectroscopy (fNIRS; authors note: fNIRS results not available at the moment) during a cognitive inhibition task.
Thirty-four drug-naive ADHD children (6-16 years) and 33 age- and sex-matched typically developing children (TD) were recruited. ADHD children were assessed before MPH first administration and after 1-month of assumption. At each assessment, participants performed a cognitive inhibition (Go-NoGo) task with a simultaneous recording of EEG and fNIRS. As for EEG, mean amplitudes and peak latencies of the N2 and P3 components of the event related potentials (ERPs) in response to both Go and NoGo stimuli were extracted from EEG recordings during the Go-NoGo blocks. The analysis of fNIRS data is currently ongoing.
At the Go-NoGo task, drug-naive ADHD children reported significantly more commission errors compared to TD peers (NoGo accuracy: 93% vs 96%; p=0.009) and greater standard deviations of reaction times (SDRTs, p=0.016). After 1-month MPH assumptions, ADHD children reported significant reductions in SDRTs (p < 0.001) and commission errors, which resulted in improved NoGo accuracy (from 93% to 96%; p=0.022). At the neurophysiological level, ADHD children (n=15) reported a slight improvement in NoGo-P3 latency (p=0.030) after MPH.
These preliminary results provide further evidence of MPH’s effect on ADHD impulsivity at the behavioral level. Moreover, despite being limited by the small sample size, our findings support the possibility to effectively monitor brain activation changes induced by MPH through EEG, further indicating NoGo-P3 latencies during Go-NoGo tasks as a potential biomarker for ADHD pathophysiology to be monitored in treatment.
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