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 .
The effects of methylphenidate on neural systems of attention in attention deficit hyperactivity disorder.
OBJECTIVE Recent studies have suggested that attention deficit hyperactivity disorder ( ADHD ) is associated with abnormalities in basal ganglia and prefrontal cortical functioning . However , these studies have primarily relied upon cognitive tasks that reflect impulse control rather than attentional mechanisms . METHOD The authors used functional magnetic resonance imaging to investigate the neural correlates of selective and divided attention in a r and omized , double-blind , placebo-controlled pharmacological challenge with methylpheni date in 15 adolescents with ADHD ( ages 14 - 17 ) , eight adolescents with reading disorder ( ages 12 - 17 ) , and four adolescents with both reading disorder and ADHD ( ages 14 - 18 ) who were scanned during both a methylpheni date and a placebo session . Fourteen healthy comparison subjects ( ages 12 - 20 ) who were not given methylpheni date served as the primary comparison group . RESULTS During the divided attention task , unmedicated subjects with ADHD or reading disorder  recruited the left ventral basal ganglia significantly less than the healthy comparison subjects . Methylpheni date led to an increase in activation in this region but had no effect on task performance .  Subjects with ADHD also recruited the middle temporal gyrus significantly less than the comparison subjects , but methylpheni date did not have a direct effect on activation in this region . CONCLUSIONS These results suggest that ADHD is associated with abnormal processing in attentional networks , with specific dysfunction in striatal circuitry . Methylpheni date may act to normalize activity within this network
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 .