Biological differences in the brain could explain why some with autism display problematic behavior, researchers say, and pinpointing the root of such issues may lead to interventions.

In a study looking at magnetic resonance imaging, or MRI, scans of kids with and without autism, researchers found a correlation between brain stem volume and a child’s propensity for aggression.

Those with a smaller brain stem were more likely to have difficulty controlling themselves, according to findings published this month in the journal Research in Autism Spectrum Disorders.

“The brain stem is really involved in autonomic activities — breathing, heart rate, staying awake — so this is evidence that there’s something core and basic, this connection between aggression and autism,” said Kevin Stephenson of Brigham Young University who worked on the study.

Researchers examined data on various regions of the brain by looking at MRI scans of 45 boys with autism and 18 typically-developing males ages 3 to 13. The MRI results were then cross-referenced with irritability scores from the Aberrant Behavior Checklist.

Overall, 14 participants with autism were deemed to have “high aggression” while the remainder of those on the spectrum and all of the typically-developing boys were in the “low aggression” group.

Reduced brain stem volume was greatly associated with being in the “high aggression” group, the study found.

Though further research is needed, the discovery could help identify better ways to treat aggression in those with autism, researchers said.

“If we know what part of the brain is different and what function that part of the brain controls, that can give us some clues into what we can do in the way of intervention,” said Terisa Gabrielsen, an assistant professor of school psychology at Brigham Young and a study co-author.