Abstract
The repetitive and restrictive behaviors common in autism are not seen as often in girls as they are in boys with the disorder. Researchers also found that there were differences in certain parts of the brain between girls and boys who exhibit these behaviors. Repetitive and restrictive behaviors are one of the most noticeable characteristics in those with autism, and they are often the red flag that leads the child to be evaluated for the disorder. Research findings raise the possibility that girls with less prominent repetitive and restrictive behaviors may miss being tested for autism or get misclassified as social communication disorder. However, 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.
The researchers compared symptoms in 128 girls and 614 boys with autism. The children were between 7 and 13 years old and all had a measured IQ above 70. Next, the investigators looked through a publicly available database for magnetic resonance imaging (MRI) brain scan results for children with and without autism. The researchers compared the MRI findings for 25 girls with autism, 25 boys with autism, 19 girls who developed typically, and 19 typically developing boys, all with the same age and IQ range. Both investigations showed that girls with autism tended to have less severe repetitive behaviors than the boys had. Social and communication difficulties were similar between both sexes, the findings showed. In the MRI results, researchers saw differences in certain parts of the brain, including those related to movement, between boys and girls with autism. However, no differences were seen in girls and boys without autism. The scientists also discovered differences in the gray matter in different parts of the brain between girls and boys among those with autism and more severe repetitive symptoms. The findings indicate that the brains of girls with autism are structured differently from those of boys with autism, and that some of these differences are linked to sex differences in behavioral impairments that characterize autism. This discovery may have implications for differences in treatments for autism based on brain structure variations between the sexes. 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. Targeting repetitive and restrictive behavior patterns by applying motor- and sensory-based strategies may generate positive behavioral change in boys presenting with high-functioning autism spectrum disorders.
Professionals disagree over implications for treatment because the sample size was small and the finding not dramatic. The link between brain findings and behavioral observations may merely reflect correlation, not causation. Supekar, K., & Menon, V. (2015). Sex differences in structural organization of motor systems and their dissociable links with repetitive/restricted behaviors in children with autism. Molecular Autism, 6, 50.
Explaining the Increase in Autism
The greater than three-fold increase in autism diagnoses among students in special education programs in the United States between 2000 and 2010 may be due in large part to the reclassification of individuals who previously would have been diagnosed with other intellectual disability disorders. Scientists reported their analysis of 11 years of special-education enrollment data on an average of 6.2 million children per year. The researchers found no overall increase in the number of students enrolled in special education. They also found that the increase in students diagnosed with autism was offset by a nearly equal decrease in students diagnosed with other intellectual disabilities that often co-occur with autism. The researchers conclude that the large increase in the prevalence of autism is likely the result of shifting patterns of diagnosis that are complicated by the variability of autism and its overlap with other related disorders.
Recent reports from the United States Centers for Disease Control and Prevention (CDC) suggest that there has been an increase in the prevalence of autism from 1 in 5000 in 1975 to 1 in 150 in 2002, then to 1 in 68 in 2012. Much of this increase has been attributed to increased awareness and a broadening of the diagnostic criteria for autism. But this new research provides the first direct evidence that much of the increase may be attributable merely to a reclassification of individuals with related neurological disorders rather than to an actual increase in the rate of new cases of autism. The researchers used data from the United States Individuals with Disabilities Education Act (IDEA) for students enrolled in special-education programs. Under IDEA, individuals are classified into one of thirteen disability categories including autism spectrum disorders, intellectual disability, emotional disturbance, other health impairment, and specific learning disabilities. Although many of the categories can co-occur in individuals with autism and show some of the same diagnostic features, children can be classified only under one category.
The research team noted more than three times the number of cases of autism in 2010 as compared to 2000; however, nearly 65 percent of this increase could be accounted for by a reduction in the number of individuals classified in the intellectual disability category in the IDEA data. The diagnostic reclassification of individuals from the category of intellectual disability to the category of autism accounts for a large proportion of the change, which varied depending on the age of the children. The researchers estimate that, for 8 year-olds, approximately 59 percent of the observed increase in autism is accounted for by reclassification, but by age 15 reclassification accounts for as much as 97 percent of the increase in autism. The high rate of co-occurrence of other intellectual disabilities with autism, which leads to diagnostic reclassification, is likely due to shared genetic factors in many neurodevelopmental disorders.—Polyak, A., Kubina, R.M. & Girirajan, S. (2015). Comorbidity of intellectual disability confounds ascertainment of autism: implications for genetic diagnosis. American Journal of Medical Genetics, 168(7), 600-608.
Theory of Mind and Learning from Others
To learn about the world around them, young children depend on information provided by others. But that’s not always the best strategy: kids will sometimes take everything grown-ups say at face value, even if they’re unreliable. New research shows that children are not as gullible as we might think – and that's especially true for those who have a good understanding of what's going on inside someone else's head. Researchers have shown that even young children can be selective in whom they prefer to learn from. Researchers noted that some preschoolers are more likely to learn from individuals with a history of making accurate claims over individuals who have been inaccurate or ignorant. Children have also been shown to prefer learning from nicer, more confident or more attractive individuals – attributes that don’t have anything to do with intelligence. Researchers speculated that certain social-cognitive abilities might explain some of these learning differences.
To test the hypothesis, researchers took 65 children through a series of tasks that tested their ability to learn new words, as well as their “theory of mind” (ToM) – that is, the intuitive understanding of one’s own and other people’s minds or mental states. The researchers tested whether the preschool-aged participants were more likely to learn new words from an accurate or inaccurate individual. They also examined whether the children were more likely to learn from a physically strong individual over a weak one. In addition, the researchers employed a series of quick ToM tests that required the children to empathize with another individual.
For the ToM tests, the participants were first introduced to several different figurines and given some background information about each: Mr. Jones likes carrots, Linda thinks her cat is hiding in the bushes, Polly and Peter have never seen what's inside the box. The children were then asked to theorize about what kind of snack Mr. Jones would want, where Linda would search for her dog and what Polly and Peter would think was inside the box. A clear pattern emerged: the children who could accurately infer the characters’ thoughts and desires were more likely to believe the individuals with the greatest verbal accuracy, rather than those who had demonstrated the greatest strength. That is, the kids with better ToM skills were less gullible.—Brosseau-Liard, P., Penney, D., & Poulin-Dubois, D. (2015) Theory of mind selectively predicts preschoolers’ knowledge-based selective word learning. British Journal of Developmental Psychology, Published online July 25, 2015.