U.S. researchers have found that behavior and brain structure linked to autism show differences between girls and boys diagnosed with the disorder.
Girls don't display the repetitive and restrictive behaviors commonly seen in autism as often as boys with the condition do, researchers at the Stanford University School of Medicine say.
This discrepancy can be at least partly explained by brain differences seen between boys and girls with autism, they reported in the journal Molecular Autism.
"Our findings suggest a potential factor that may contribute to the relatively low proportion of females with autism," says Kaustubh Supekar, a postdoctoral researcher in the Stanford medical school and lead author of the study.
Repetitive/restricted behaviors are considered one autism's core symptoms, alongside communication difficulties and social impairment.
The fact that girls are less likely to display such behaviors raises the likelihood that they may miss out on being tested for the condition, or they may be misclassified as having a social communication disorder, Supekar says.
"On the other hand, boys with more pronounced repetitive and restrictive behaviors may show more false positives for autism spectrum disorders, given that repetitive and restricted behaviors are not specific to children with autism and are also observed in other neurodevelopmental disorders," he added.
While girls with autism tended to display less severe repetitive behaviors than seen in boys, communication and social difficulties were similar in both boys and girls, the researchers found.
Focusing on brain structure using MRI scans demonstrated variances in certain brain regions, including those involved in movement, between autistic girls and autistic boys, they reported.
In boys and girls without autism, no comparable differences existed, they said.
This finding of brain structure differences could have implications for different choices in treatments for autism as applied to girls and boys, experts suggest.
"Treatment for girls may best focus on building behavior skills that support social interactions and social communication as most important to remediate autism spectrum disorder behaviors in girls," says Mayra Mendez of Providence Saint John's Child and Family Development Center in Santa Monica, Calif.
In contrast, in boys diagnosed with high-functioning autism spectrum disorders, positive behavioral change might best be generated by using motor- and sensory-based strategies to target repetitive and restrictive behaviors, she suggests.
Other experts caution that the link between brain differences and observed behavior may reflect an association but does not automatically suggest a cause and effect.
