New research suggests that boys and girls with autism have differences in behavior and brain structure.

Researchers at the Stanford University School of Medicine found that girls with autism display less repetitive and restricted behavior than boys do. They also found that brain differences between boys and girls with autism help explain this discrepancy.

"We wanted to know which specific clinical manifestations of autism show significant gender differences, and whether patterns in the brain's gray matter could explain behavioral differences," Vinod Menon,  senior author of the study, said in a statement. "Understanding this is really quite crucial clinically."

For the study, researchers used two large, public databases to examine nearly 800 children with high-functioning forms of autism in the United States.

Researchers found that girls and boys did not differ on social behavior and communication skills, but that girls had less-severe repetitive and restricted behaviors.

"This replication provides the strongest evidence to date for gender differences in a core phenotypic feature of autism," Menon said.

Repetitive and restricted behavior is perhaps the most widely recognized of the three core features of autism. It can show up as a child's preoccupation with a narrow interest, inflexibility about routines or repetitive motions such as hand-flapping. The other core features of autism are social and communication deficits.

Researchers also conducted a brain scan which revealed several gender differences in brain structure between typically developing boys and girls, consistent with the findings of earlier studies.

Children with autism, however, had a dissimilar set of gender differences in their brains -- specifically, in the motor cortex, supplementary motor area and a portion of the cerebellum. These regions affect motor function and planning of motor activity.

The findings are detailed in the journal Molecular Autism.