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Autism Produces Greater Behavioral Changes in Girls

Study of preschoolers finds that girls with autism differ more from other girls than boys with autism differ from typical boys
May 13, 2015

New research on preschoolers finds that the behavior of girls with autism differs more from that of “neurotypical” girls than the behavior of boys with autism differs from that of other boys.

“Most studies of gender differences compare males and females with autism to each other,” says lead researcher Christine Nordahl, of the University of California-Davis MIND Institute. “But only by comparing girls with autism to other girls can we really see the extent of their social impairments and need for support.”

Dr. Nordahl presented the preliminary results of her team’s behavioral study at the International Meeting for Autism Research (IMFAR) in Salt Lake City.

For more daily news coverage from IMFAR, click here.

“Our finding suggests that girls with autism have greater social impairments than do boys,” Dr. Nordahl adds. This is consistent, she says, with previous research suggesting that, while girls have some degree of protection from autism, when they are affected, their symptoms tend to be more severe.

Comparisons of girls with autism to their unaffected peers may be crucial to improving understanding of the autism-related challenges girls and women face, Dr. Nordahl says. Unfortunately, enrolling sufficient numbers of girls into autism studies remains a great challenge. Autism affects nearly five times more boys (1 in 42) than girls (1 in 189).

The preliminary results of Dr. Nordahl’s ongoing study includes information from professional evaluations and parent surveys on 153 preschool boys and 46 preschool girls with autism. It compares their behaviors to those of 58 typically developing boys and 38 typically developing girls.

Do brain differences underlie behavior?
Dr. Nordahl also leads the Girls with Autism Imaging of Neurodevelopment (GAIN) Study. In a related brain-imaging study published last week, her team reported differences in the brains of 27 preschool girls versus 112 preschool boys with autism. More specifically, they found differences in the fibers that extend from the brain’s corpus callosum into the frontal lobes. (See image below.)

The corpus callosum forms a kind of bridge uniting the brain’s two halves, or hemispheres. The frontal lobes control many aspects of higher-level thought including social behavior and decision making.

 “Differences in the patterns of callosal fibers projecting to these areas could lead to differences in how autism manifests in boys and girls,” Dr. Nordahl says. Previous studies have associated autism with changes in the corpus callosum. However, these studies included very few girls or women, Dr. Nordahl notes.

Over the next three years, Dr. Nordahl hopes to enroll another 100 preschool-age girls with autism in her research. Learn more about the GAIN study, including recruitment across California here.