ADHD Brain Matures, but Later

Nov. 12, 2007 -- ADHD (attention deficit hyperactivity disorder) may delay, but not prevent, the development of the brain's attention center.

Researchers from the National Institute of Mental Health (NIMH) and Canada's McGill University reported that news today.

The finding "should be reassuring to families and could help to explain why many youth eventually seem to grow out of the disorder," the NIMH's Philip Shaw, PhD, says in a news release.

Shaw's team scanned the brains of 446 children, teens, and young adults -- half of whom had been diagnosed with ADHD -- twice, about three years apart.

The scientists measured the thickness of different parts of the brain as shown on the brain scans.

Typical kids with ADHD were 10.5 years old when the part of the brain's prefrontal cortex that controls attention and plans movements reached its peak thickness (a sign of maturity).

Peak thickness in that brain area happened three years earlier in people without ADHD.

Another area of the brain -- the motor cortex, which carries out orders for planned movements -- reached peak thickness a few months faster in children with ADHD compared to those without ADHD.

So in short, the brain's motion center generally matured faster than normal and its "executive" center typically developed slower than normal with ADHD.

But that maturation process happens the same way, just at a different pace, with or without ADHD.

The findings appear in this week's online early edition of Proceedings of the National Academy of Sciences.