RESULTS In ADHD patients the middle and inferior frontal gyri , basal ganglia , and cerebellum were most often affected by MPH .
The middle and inferior frontal gyri were frequently affected by MPH during inhibitory control tasks .
Throughout nine task-based fMRI studies investigating MPH 's effect on the brains of pediatric patients with ADHD , MPH result ed in increased activation within frontal lobes , basal ganglia , and cerebellum .
In most cases , this increase " normalized " activation of at least some brain areas to that seen in typically developing children
OBJECTIVE Attention-deficit/hyperactivity disorder ( ADHD ) is a psychiatric disorder affecting 5 % of children .
Methylpheni date ( MPH ) is a common medication for ADHD .
Studies examining MPH 's effect on pediatric ADHD patients ' brain function using functional magnetic resonance imaging ( fMRI ) have not been compiled .
The goals of this systematic review were to determine ( 1 ) which areas of the brain in pediatric ADHD patients are modulated by a single dose of MPH , ( 2 ) whether areas modulated by MPH differ by task type performed during fMRI data acquisition , and ( 3 ) whether changes in brain activation due to MPH relate to clinical improvements in ADHD-related symptoms .
Clinically Relevant Doses of Methylphenidate Significantly Occupy Norepinephrine Transporters in Humans In Vivo
BACKGROUND Attention-deficit/hyperactivity disorder is a psychiatric disorder that starts in childhood . The mechanism of action of methylpheni date , the most common treatment for attention deficit hyperactivity disorder , is unclear . In vitro , the affinity of methylpheni date for the norepinephrine transporter ( NET ) is higher than that for the dopamine transporter ( DAT ) . The goal of this study was to use positron emission tomography to measure the occupancy of brain norepinephrine transporter by methylpheni date in vivo in humans . METHODS We used (S , S)-[¹¹C ] methylreboxetine ( [¹¹C]MRB ) to determine the effective dose 50 ( ED₅₀ ) of methylpheni date for NET . In a within-subject design , healthy subjects ( n = 11 ) received oral , single-blind placebo and 2.5 , 10 , and 40 mg of methylpheni date 75 min before [¹¹C]MRB injection . Dynamic positron emission tomography imaging was performed for 2 hours with the High Resolution Research Tomograph . The multilinear reference tissue model with occipital cortex as the reference region was used to estimate binding potential non-displaceable ( BP(ND ) ) in the thalamus and other NET-rich regions . RESULTS BP(ND ) was reduced by methylpheni date in a dose-dependent manner in thalamus and other NET-rich regions . The global ED₅₀ was estimated to be .14 mg/kg ; therefore , the average clinical maintenance dose of methylpheni date ( .35-.55 mg/kg ) produces 70 % to 80 % occupancy of NET . CONCLUSIONS For the first time in humans , we demonstrate that oral methylpheni date significantly occupies NET at clinical ly relevant doses . The ED₅₀ is lower than that for DAT ( .25 mg/kg ) , suggesting the potential relevance of NET inhibition in the therapeutic effects of methylpheni date in attention-deficit/hyperactivity disorder
RESULTS In ADHD patients the middle and inferior frontal gyri , basal ganglia , and cerebellum were most often affected by MPH .
The middle and inferior frontal gyri were frequently affected by MPH during inhibitory control tasks .
Throughout nine task-based fMRI studies investigating MPH 's effect on the brains of pediatric patients with ADHD , MPH result ed in increased activation within frontal lobes , basal ganglia , and cerebellum .
In most cases , this increase " normalized " activation of at least some brain areas to that seen in typically developing children
OBJECTIVE Attention-deficit/hyperactivity disorder ( ADHD ) is a psychiatric disorder affecting 5 % of children .
Methylpheni date ( MPH ) is a common medication for ADHD .
Studies examining MPH 's effect on pediatric ADHD patients ' brain function using functional magnetic resonance imaging ( fMRI ) have not been compiled .
The goals of this systematic review were to determine ( 1 ) which areas of the brain in pediatric ADHD patients are modulated by a single dose of MPH , ( 2 ) whether areas modulated by MPH differ by task type performed during fMRI data acquisition , and ( 3 ) whether changes in brain activation due to MPH relate to clinical improvements in ADHD-related symptoms .