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 .
Volumetric MRI differences in treatment-naïve vs chronically treated children with ADHD
Objective : To determine if there are differences in the volume of the cau date and anterior cingulate cortex ( ACC ) between children with attention deficit hyperactivity disorder ( ADHD ) and controls , and if such differences are related to the subjects ’ history of stimulant treatment . Methods : We performed a case-control study in an academic medical center . Twenty-one healthy controls , 16 children with ADHD , combined type with a history of stimulant treatment , and 14 children with ADHD , combined type treatment naïve , underwent structural MRI . All children with ADHD were medication-free at the time of the MRI .  Regional hemispheric volumes ( in cm3 ) of cau date and anterior cingulate cortex were determined . Results : There were significant differences bilaterally on cau date volume for both ADHD groups vs controls , with no difference between the ADHD groups on either side . In contrast , the right ACC was significantly smaller for the ADHD-treatment naïve ( ADHD/TN ) group compared to the ADHD-treated ( ADHD/Rx ) and control group . The volume of left ACC approached significance contrast between ADHD/RX and ADHD/TN . There were no differences found between the ADHD/Rx and controls on the ACC volumes bilaterally . Conclusions : The results from this study indicate a relationship of previous treatment history with cau date and anterior cingulate volumetric changes in children with attention deficit hyperactivity disorder – combined type
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 .