The stimulant drug methylphenidate "normalizes" activation of several brain areas in young patients with attention-deficit/hyperactivity disorder (ADHD), according to a review published in the May Harvard Review of Psychiatry. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.
Studies using functional magnetic resonance imaging (fMRI) show increased activation of key brain areas after a dose of methylphenidate in young patients with ADHD, according to the systematic review by Constance A. Moore, PhD, and colleagues of the University of Massachusetts Medical School. They write, "In most cases, this increase 'normalized' activation of at least some brain areas to levels seen in typically developing children."
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In a research review, Dr Moore and colleagues identified nine previous studies using fMRI to study patterns of brain activation in response to a single dose of methylphenidate. Perhaps best known by the brand name Ritalin, methylphenidate is a common and effective treatment for ADHD. "Although methylphenidate has been shown to significantly improve the behavioral symptoms associated with ADHD, both the mechanism behind its therapeutic effect and its direct effects on brain function are unknown," the researchers write.
The studies evaluated methylphenidate-induced fMRI changes in various brain areas, as the participants performed different types of tasks. Most of the studies included adolescent boys with ADHD, along with matched groups of young people without ADHD.
Methylphenidate altered activation patterns in widely distributed areas of the brain in ADHD patients, the results showed. The main brain areas involved were the frontal lobes, the basal ganglia, and cerebellum: "Abnormalities in these regions have all been implicated in patients with ADHD," Dr Moore and coauthors write.
Different areas were activated during different types of fMRI tasks. Several studies assessed performance on "inhibitory control" tasks-the ability to control certain types of accustomed ("prepotent") responses. In three out of five studies, methylphenidate "at least partially normalized" brain activation in ADHD patients, compared to healthy young people.
Different Tasks Affect Different Brain Areas