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.
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.