Language problems are a common symptom of autism spectrum disorder (ASD). Although language issues appear frequently with ASD, their cause is not understood. A new study finds that activation in several language-related brain regions is abnormally slow in children with ASD. The finding may help researchers understand why so many people with ASD struggle with language.
The researchers hypothesized that if an individual has trouble with language, he or she likely struggles with the fundamentals of speech production. They tested this theory with 21 with ASD and 21 controls, all aged 6 to 17. The children completed three tasks while the researchers measured the timing of their brain activation using magnetoencephalography (MEG). The first task was opening the mouth. The second was speaking the syllable pa. The third was speaking the syllables pa, da, and ka as a single utterance. These tasks demonstrated the children’s abilities with movement, language, and integrating movement and language, respectively. These three skills are the building blocks of language production.
The MEG data showed that, for controls, the tasks generated the most activity in areas of the brain’s cerebral cortex. The researchers compared the activation of these areas in the control group and the children with ASD. The children with ASD demonstrated significant delays in all three tasks.
- When opening their mouths, children with ASD had a 38-millisecond delay in the activation of the part of the cortex that governs motor planning.
- When producing one syllable, children with ASD had a 37-millisecond delay in the frontal cortex’s language hub.
- When producing a multi-syllable utterance, children with ASD had an 81-millisecond delay in the insula, which integrates the brain and body.
“For each building block, there’s a new delay that’s introduced,” explained lead investigator Elizabeth Pang, neurophysiologist at the Hospital for Sick Children in Toronto. “There’s something very fundamentally different in the nervous system of an autistic child that’s kind of blocking things up and slowing things down.”
The findings fit with a previous study’s results that toddlers with the poorest motor skills tend to have the lowest speech fluency later on. It is possible that delays in brain circuits may be at the heart of some symptoms of autism. However, the study is not definitive and it is not clear how the patterns observed in this study relate to language skills. More research is required to fully understand the relationship between brain activation and linguistic abilities in ASD.
This research is published in the journal Autism Research.
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