Impulsive children become thoughtful adults only after years of improvements to the brain's information highways, a team reports in Current Biology.
A study of nearly 900 young people ages 8 to 22 found that the ability to control impulses, stay on task and make good decisions increased steadily over that span as the brain remodeled its information pathways to become more efficient.
The finding helps explain why these abilities, known collectively as executive function, take so long to develop fully, says Danielle Bassett, an author of the study and an associate professor of bioengineering at the University of Pennsylvania.
"A child's ability to run or to see is very well developed by the time they're 8," she says. "However, their ability to inhibit inappropriate responses is not something that's well developed until well into the 20s."
The results also suggest it may be possible to identify adolescents at risk of problems related to poor executive function, says Joshua Gordon, director of the National Institute of Mental Health, which helped fund the study. These include "all kinds of disorders such as substance abuse, depression and schizophrenia," he says.