An extremely important article by researchers from the National Institute of Mental Health has just been published in the Proceedings of the National Academies of Sciences. It suggests that children with Attention Deficit Hyperactivity Disorder (ADHD) have brains that develop more slowly than those of children without ADHD. However in most cases they still follow a normal pattern of development.
In a study of 450 children, 225 of whom had ADHD, the researchers found that the cerebral cortex of children with ADHD developed about three years more slowly.
The primary measure that they used was the peak thickness of the brain, which is normally taken to be a sign of maturity. Half of the children with ADHD reached peak thickness when they were an average of 10.5 years old, compared with 7.5 years among children without ADHD.
Even if the brain is developing more slowly, the fact that it appears to grow normally is reassuring, and may explain why a substantial proportion of children with ADHD do grow out of it as they get older. Though it still leaves us with several questions:
- Why does the delay occur at all?
- Why do so many people NOT grow out of it, and have persistent symptoms in adulthood?
- Is the brain really “catching up?” The brains of people without ADHD also continue to develop and grow
The National Institute of Mental Health has also published a nice press release that includes a video of brain maturation. You can find it here.
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