Brain structures of girls and boys with autism are different

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A new study has shown that girls and boys with autism differ in their behaviour and one of the primary reasons behind this discrepancy is difference in their brain structures.

Researchers found strong gender differences in autism with girls showing less repetitive and restricted behaviour than boys. The findings are an outcome of the study wherein researchers were looking to investigate which specific clinical manifestations of autism show significant gender differences, and whether patterns in the brain’s gray matter could explain behavioral differences.

For their study, researchers used two large, public databases to examine nearly 800 children with high-functioning forms of autism in the United States. Postdoctoral scholar Kaustubh Supekar, PhD, the study’s lead author said that they found strong gender differences in autism patients.

Researchers found that in children diagnosed with the high-functioning form of autism, boys outnumbered girls by four to one. Scientists were interested in comparing the expression of core features of the disorder between sexes because they have long suspected girls with autism may display symptoms differently, causing them to be underdiagnosed or making it harder for them to get the most appropriate treatment.

The study examined the severity of autism symptoms in 128 girls and 614 boys registered with the National Database for Autism Research. The children ranged in age from 7 to 13, had IQ scores above 70, and had been evaluated with standard tests for autistic behavior. The boys and girls were matched for age, and had the same average IQ. Girls and boys had similar scores for social behavior and communication. But girls had lower (more normal) scores on a standard measurement of repetitive and restricted behaviors.

The researchers then examined data from the Autism Brain Imaging Data Exchange that included structural MRI brain scans of 25 boys with autism, 25 girls with autism, 19 typically developing boys and 19 typically developing girls. The individuals among the groups were matched for age and IQ. The researchers again found that girls and boys did not differ on social behavior and communication skills, but that girls had less-severe repetitive and restricted behaviors.

The brain-scan analysis 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 researchers noted that many repetitive behaviors, such as hand-flapping, have a motor component.

“Girls and boys with autism differ in their clinical and neurobiological characteristics, and their brains are patterned in ways that contribute differently to behavioral impairments,” said Vinod Menon, PhD, professor of psychiatry and behavioral sciences.