[STS2-4B-2] Acute neuropharmacological effects of ADHD medications on children with attention deficit/hyperactivity disorder as assessed using fNIRS
Attention Deficit Hyperactivity Disorder (ADHD) is one of the most prevalent developmental disorders. The non-stimulant drug, atomoxetine (ATX) as well as the stimulant drug, methylphenidate (MPH) have been recommended as primary medications. One promising approach for objectively assessing the efficacy of either medication for ADHD children is the exploration of distinct biological markers and their testing with a noninvasive neuroimaging modality. In a series of studies, we explore the neural substrate for effects of ATX and MPH on inhibitory and attention controls in school-aged ADHD using fNIRS. We monitored the oxy-hemoglobin signal changes of ADHD (6 to 14 years old) performing go/no-go or oddball tasks before and 1.5 h after ATX, MPH or placebo administration, in a randomized, double-blind, placebo-controlled, crossover design. We also included age- and gender-matched normal controls without medication. In the control subjects, the go/no-go task recruited the right inferior and middle prefrontal gyri (IFG/MFG), and this activation was absent in pre-medicated ADHD. The reduction of right IFG/MFG activation was acutely normalized after ATX and MPH administration but not placebo administration in ADHD. In the control subjects, the oddball task recruited the right IFG/MFG and the inferior parietal cortex. The right prefrontal activation was normalized after ATX and MPH administration in ADHD, but the right inferior parietal normalization was specific to ATX. These results led us to conclude that fNIRS successfully visualized differential neuropharmacological effects of ATX and MPH to up-regulate the noradrenaline and dopamine systems in the inhibitory and attentional networks in the brains of ADHD.