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Biol Psychiatry. 2014 Oct 15;76(8):616-28. doi: 10.1016/j.biopsych.2013.10.016. Epub 2013 Oct 24.

Effects of stimulants on brain function in attention-deficit/hyperactivity disorder: a systematic review and meta-analysis.

Author information

1
Departments of Child and Adolescent Psychiatry (KR, AAA, AIC, AS) and Neuroimaging (MJB), Institute of Psychiatry, King's College London, United Kingdom. Electronic address: katya.rubia@kcl.ac.uk.
2
Departments of Child and Adolescent Psychiatry (KR, AAA, AIC, AS) and Neuroimaging (MJB), Institute of Psychiatry, King's College London, United Kingdom.
3
Departments of Neuroimaging, Institute of Psychiatry, King's College London, United Kingdom.
4
Fundació per a la Investigació i la Docència Maria Angustias Giménez Research Unit, Germanes Hospitalaries and Centro de Investigación Biomédica en Red de Salud Mental (JR), Barcelona, Spain.

Abstract

BACKGROUND:

Psychostimulant medication, most commonly the catecholamine agonist methylphenidate, 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 elucidate underlying neurocognitive effects. We tested methylphenidate 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.

METHODS:

The fMRI study compared 20 adolescents with ADHD under either placebo or methylphenidate in a randomized controlled trial while performing stop, working memory, and time discrimination tasks. The meta-analysis was conducted searching PubMed, ScienceDirect, Web of Knowledge, Google Scholar, and Scopus databases. Peak coordinates of clusters of significant effects of stimulant medication relative to placebo or off medication were extracted for each study.

RESULTS:

The fMRI analysis showed that methylphenidate 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 datasets and 212 children with ADHD, showed that stimulants most consistently enhanced right IFC/insula activation, which also remained for a subgroup analysis of methylphenidate 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.

KEYWORDS:

ADHD; fMRI; meta-analysis; methylphenidate; review; stimulants

PMID:
24314347
PMCID:
PMC4183380
DOI:
10.1016/j.biopsych.2013.10.016
[Indexed for MEDLINE]
Free PMC Article

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