Brains with autism are more symmetrical than others, but in this case, symmetry means something a little different from what you might expect.
A study published in the Journal of the American Academy of Child & Adolescent Psychiatry says imaging revealed that children and adolescents with autism spectrum disorder have fewer asymmetries in their brains compared to non-autistic peers, suggesting that the two sides of their brains are not divvying up tasks in the same way. The study, from San Diego State University neuropsychologists, called what the two halves of the brain are supposed to be doing “different processing modes” — the left is more specialized while the right is more integrative. That division of labor creates asymmetry in the brain, but that effect was “diminished” in the youths with autism.
Autism spectrum disorder is a group of developmental disorders that are most well-known for causing difficulty communicating or interacting with other people. According to the National Institutes of Health, signs of the disorder could include: being upset by a change in routine; a lack of eye contact; difficulty holding a conversation; being unable to understand other people’s perspectives or actions; and responding to others’ emotions or words in an unusual or incongruous way. People with autism may also have limited interests and repetitive behaviors. The symptoms vary, with some experiencing only mild impairment while in others the effect is severe.
The university explained in a statement that typical brain development includes separating tasks between the left and right hemispheres: “The left hemisphere, for instance, is involved in analyzing specific details of a situation, while the right hemisphere is involved in integrating all the various streams of information coming into the brain.” That right hemisphere has more densely packed connections in a typical brain, according to the imaging study, whereas autistic brains have more evenly distributed connections across the hemispheres.
The difference between that typical development and the development of a brain with autism could explain how the disorder is linked to the cognitive difficulties those people experience. “Many people with ASD are very good at seeing details but have difficulty putting it all together into a cohesive narrative,” the university said, referencing the idiom that they are “not seeing the forest for the trees.”
However, the statement noted, researchers must still determine whether the more even distribution of connections between the brain’s left and right hemispheres are causing the cognitive impairments, or vice versa.