RESULTS The fMRI analysis showed that methylpheni date significantly enhanced activation in bilateral inferior frontal cortex (IFC)/insula during inhibition and time discrimination but had no effect on working memory networks .
The meta- analysis , including 14 fMRI data sets and 212 children with ADHD , showed that stimulants most consistently enhanced right IFC/insula activation , which also remained for a subgroup analysis of methylpheni date effects alone .
A more lenient threshold also revealed increased putamen activation .
CONCLUSIONS Psychostimulants most consistently increase right IFC/insula activation , which are key areas of cognitive control and also the most replicated neurocognitive dysfunction in ADHD .
These neurocognitive effects may underlie their positive clinical effects
BACKGROUND Psychostimulant medication , most commonly the catecholamine agonist methylpheni date , is the most effective treatment for attention-deficit/hyperactivity disorder ( ADHD ) .
However , relatively little is known on the mechanisms of action .
Acute effects on brain function can eluci date underlying neurocognitive effects .
We tested methylpheni date effects relative to placebo in functional magnetic resonance imaging ( fMRI ) during three disorder-relevant tasks in medication-naïve ADHD adolescents .
In addition , we conducted a systematic review and meta- analysis of the fMRI findings of acute stimulant effects on ADHD brain function .
Methylphenidate Normalizes Resting-State Brain Dysfunction in Boys With Attention Deficit Hyperactivity Disorder
We used resting-state functional magnetic resonance imaging ( RS-fMRI ) to investigate the acute effects of methylpheni date hydrochloride ( MPH ) on spontaneous brain activity in children with attention deficit hyperactivity disorder ( ADHD ) . In all , 23 boys with ADHD were scanned twice , under either 10 mg dose of MPH or placebo , in a r and omized , cross-over , counterbalanced placebo-controlled design . 32 Matched healthy controls were scanned once for comparison . Seven of the 23 ADHD boys participated in a follow-up 8-week MPH treatment . A regional homogeneity ( ReHo ) method was applied to characterize the local synchronization of spontaneous brain activity .  ADHD boys under placebo compared with controls showed decreased ReHo in bilateral dorsolateral prefrontal cortices and increased ReHo in bilateral sensorimotor and parieto-visual cortices . Relative to placebo , MPH upregulated ReHo in bilateral ventral prefrontal cortices and cerebellar vermis , and downregulated ReHo in right parietal and visual areas that overlapped with the abnormally enhanced activities . When under MPH , ReHo differences between patients and controls were no longer observed . The preliminary prediction analysis revealed that the decreased ReHo in right parietal cortex after the acute MPH was positively correlated with the decreased symptom scores after the 8-week MPH treatment in the seven patients . We show that an acute dose of MPH normalized all fronto-parieto-cerebellar dysfunctions in boys with ADHD during the resting state . Preliminary findings furthermore suggest the potential of RS-fMRI as a prognostic imaging tool to identify response to MPH treatment
RESULTS The fMRI analysis showed that methylpheni date significantly enhanced activation in bilateral inferior frontal cortex (IFC)/insula during inhibition and time discrimination but had no effect on working memory networks .
The meta- analysis , including 14 fMRI data sets and 212 children with ADHD , showed that stimulants most consistently enhanced right IFC/insula activation , which also remained for a subgroup analysis of methylpheni date effects alone .
A more lenient threshold also revealed increased putamen activation .
CONCLUSIONS Psychostimulants most consistently increase right IFC/insula activation , which are key areas of cognitive control and also the most replicated neurocognitive dysfunction in ADHD .
These neurocognitive effects may underlie their positive clinical effects
BACKGROUND Psychostimulant medication , most commonly the catecholamine agonist methylpheni date , is the most effective treatment for attention-deficit/hyperactivity disorder ( ADHD ) .
However , relatively little is known on the mechanisms of action .
Acute effects on brain function can eluci date underlying neurocognitive effects .
We tested methylpheni date effects relative to placebo in functional magnetic resonance imaging ( fMRI ) during three disorder-relevant tasks in medication-naïve ADHD adolescents .
In addition , we conducted a systematic review and meta- analysis of the fMRI findings of acute stimulant effects on ADHD brain function .