Study Suggests Girls’ Brains Are More Resilient

childA study published in The American Journal of Human Genetics suggests that girls are less likely to develop symptoms of autism(ASD) or attention deficit hyperactivity disorder (ADHD) because their brains are more resilient than those of males. The study followed 762 families affected by an autism spectrum disorder, 653 males and 109 females.

Researchers looked at two types of genetic mutations, copy-number variants (CNV) and single-nucleotide variants (SNV), and they found that the female subjects had approximately two to three times as many CNVs, and substantially more SNVs as well. Essentially, the study suggests that males are more likely to develop autism because their brains are affected by fewer mutations than female brains.

Lead author Sebastien Jacquemont of the University Hospital of Lausanne, Switzerland.

“The data suggests – and it would require additional experiments to really prove this- but it looks like there is a resilience in brain development that is much higher in females than in males.”

Co-author Evan Eichler of the University of Washington, Seattle, says,

“There are two ways of looking at it – boys are more susceptible or girls are protected, and so it takes more insult in the genome of a girl to push them over a threshold to develop autism or to develop developmental delay compared to a boy.”

This study may add support for Simon Baron-Cohen’s “extreme male brain” hypothesis, which suggests that autism is an exaggeration of typical male brain characteristics.

Other researchers wonder if, in fact, males are more likely to be diagnosed with autism due to current diagnostic criteria and social bias. A Swedish study published in Research in Developmental Disabilities suggests that females with high-functioning autism or Aspergers syndrome exhibit different symptoms and behaviors than their male counterparts, leading to under-diagnosis. Basically, the testing criteria is based on research on male subjects, and tends to miss females who are not at the severe end of the spectrum.

Somer Bishop, assistant professor of pediatrics at Cincinnati Children’s Hospital in Ohio, says,

“Many of these [testing instruments] are modeled on the earliest groups of children identified with autism, many of whom were boys. . . I think that very, very smart girls go undetected at higher rates than boys do. [Girls] often present with more subtle difficulties.”

For example, girls are more likely to be interested in pretend play, sometimes obsessively. Girls are also more likely to be socially motivated and interested in friendship, but have difficulty initiating and maintaining friendships with same-age peers. They are also more likely to be quiet and passive, unlike their male counterparts, who are more likely to act out in meltdowns or show aggression.

For now, it seems clear that there are definite gender differences in autism spectrum disorders. Are female brains more resilient than male brains, or has the research simply not accounted for gender differences present in autism? Both scenarios are likely to contribute to the gender differences. More research is needed to shed some light on the issue.