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 .
Psychostimulant treatment and the developing cortex in attention deficit hyperactivity disorder.
OBJECTIVE While there has been considerable concern over possible adverse effects of psychostimulants on brain development , this issue has not been examined in a prospect i ve study . The authors sought to determine prospect ively whether psychostimulant treatment for attention deficit hyperactivity disorder ( ADHD ) was associated with differences in the development of the cerebral cortex during adolescence . METHOD Change in cortical thickness was estimated from two neuroanatomic MRI scans in 43 youths with ADHD . The mean age at the first scan was 12.5 years , and at the second scan , 16.4 years . Nineteen patients not treated with psychostimulants between the scans were compared with an age-matched group of 24 patients who were treated with psychostimulants .  Further comparison was made against a template derived from 620 scans of 294 typically developing youths without ADHD . RESULTS Adolescents taking psychostimulants  differed from those not taking psychostimulants in the rate of change of the cortical thickness in the right motor strip , the left middle/inferior frontal gyrus , and the right parieto-occipital region . The group difference was due to more rapid cortical thinning in the group not taking psychostimulants ( mean cortical thinning of 0.16 mm/year [ SD=0.17 ] , compared with 0.03 mm/year [ SD=0.11 ] in the group taking psychostimulants ) . Comparison against the typically developing cohort without ADHD showed that cortical thinning in the group not taking psychostimulants was in excess of age-appropriate rates . The treatment groups did not differ in clinical outcome , however . CONCLUSIONS These findings show no evidence that psychostimulants were associated with slowing of overall growth of the cortical mantle
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 .