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-Elicited Dopamine Increases in Ventral Striatum Are Associated with Long-Term Symptom Improvement in Adults with Attention Deficit Hyperactivity Disorder
Stimulant medications , such as methylpheni date , which are effective treatments for attention deficit hyperactivity disorder ( ADHD ) , enhance brain dopamine signaling . However , the relationship between regional brain dopamine enhancement and treatment response has not been evaluated . Here , we assessed whether the dopamine increases elicited by methylpheni date are associated with long-term clinical response . We used a prospect i ve design to study 20 treatment-naive adults with ADHD who were evaluated before treatment initiation and after 12 months of clinical treatment with a titrated regimen of oral methylpheni date . Methylpheni date -induced dopamine changes were evaluated with positron emission tomography and [11C]raclopride ( D2/D3 receptor radiolig and sensitive to competition with endogenous dopamine ) . Clinical responses were assessed using the Conners ' Adult ADHD Rating Scale and revealed a significant reduction in symptoms of inattention and hyperactivity with long-term methylpheni date treatment . A challenge dose of 0.5 mg/kg intravenous methylpheni date significantly increased dopamine in striatum ( assessed as decreases in D2/D3 receptor availability ) . In the ventral striatum , these dopamine increases were associated with the reductions in ratings of symptoms of inattention with clinical treatment . Statistical parametric mapping additionally showed dopamine increases in prefrontal and temporal cortices with intravenous methylpheni date that were also associated with decreases in symptoms of inattention . Our findings indicate that dopamine enhancement in ventral striatum ( the brain region involved with reward and motivation ) was associated with therapeutic response to methylpheni date , further corroborating the relevance of the dopamine reward/motivation circuitry in ADHD . It also provides preliminary evidence that methylpheni date -elicited dopamine increases in prefrontal and temporal cortices may also contribute to the clinical response
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 .