Large-scale MRI study confirms ADHD brain differences

A large-scale study has shown differences in brain size between kids with and without ADHD. The research also shows that these differences seem to lessen as kids with ADHD mature into adults. The study was published in The Lancet and funded by the National Institutes of Health.

This is one of the largest-scale studies on ADHD and the brain. Researchers looked at MRI brain scans of more than 3,000 kids and adults.

The subjects included men and women, ranging in age from 4 to 63. A little more than half have ADHD. The scans were taken at 23 different locations in the United States, Europe, China, and Brazil.

Understood experts Ellen Braaten, Thomas E. Brown, and Bob Cunningham reviewed the study. Here’s the takeaway.

Key findings

Researchers compared seven parts of the brain in people with and without ADHD. They found some significant differences in brain size:

• Five of the seven brain regions were smaller in kids with ADHD.

• The area with the greatest size difference was the amygdala. This part of the brain is related to emotional control and self-control. It also plays a role in being able to prioritize actions. Areas linked to memory and learning were also smaller.

• ADHD medication didn’t cause the differences. Kids who had used medication had the same pattern of differences as those who had never used medication.

• These size differences didn’t exist in adults with ADHD. After the teen years, the size was similar between people with and without ADHD.

This is the first large study to look at brain size differences and ADHD. Earlier studies involved too few people to be reliable. They also were inconsistent in how they measured brain differences.

“This study just expanded something we already know — there are differences in brain structure in people with ADHD,” says Brown. “Even though ADHD is a functional problem, it’s connected to something structural.”

Key takeaways for parents

This is a reliable and significant study that confirms ADHD is a brain-based condition. It dispels some of the myths around ADHD, including that it’s “not real.” That can help reduce stigma for both kids and parents.

It doesn’t mean that brain scans can be used to diagnose ADHD, however. The researchers looked at many scans and found differences across a lot of people. But those differences may or may not exist for any individual child.

And while the study shows that kids’ brains seem to mature as they become adults, it doesn’t mean ADHD symptoms go away. ADHD is a lifelong condition. But there are effective treatments and strategies that can help.

Learn about ADHD treatment, including medication, behavior therapy and alternative treatments. Discover how MRIs work and what they can tell us about the brain. And watch as an expert explains how ADHD symptoms can change as kids get older.