A Neurological Basis for ADHD

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Shaw and others caution that it's too early to use the findings to diagnose the disorder or to influence treatment. "But with more research, it may be possible to do an MRI study before starting medication and then predict what type of treatment might be best for that individual based on their brain image and genotype," says Kennedy.

The findings may also help quell some controversy surrounding the disorder. ADHD is diagnosed mainly by a child's behavior, and some have argued that pushy pharmaceutical companies, impatient parents and overburdened teachers have led to chronic overdiagnosis and unnecessary medication of children. Identifying a mechanism by which a genetic allele might influence ADHD helps solidify a neurological basis of the disorder.

In addition, the study supports the idea that ADHD sometimes disappears in adulthood. While that idea had gone out of favor, recent large-scale follow studies suggest that some children do get better and stay better, says James Swanson, professor of psychiatry at University of California, Irvine. The new findings may provide a biological basis for this pattern, he says.

He adds that the gene itself is very interesting. The variation linked to ADHD shows signs that it was selected for during evolution, suggesting that it confers some kind of advantage. "[The variation] might be linked to a different way of thinking or acting that is diagnosed as ADHD in childhood but could be beneficial at other times in development," says Swanson.

ADHD brains: Scientists found that children with ADHD who had a particular genetic variation started out with an unusually thin cortex in the parts of the brain important for attention. But over time, their brains became indistinguishable from those of healthy teens. This time-lapse series of images shows how their brains normalized over time--the brightly colored sections indicate the parts of the brain that were most different in the ADHD group. These sections disappear as the children aged. Press the "play" button to watch the gradual change, or move the slider to control the process.