The brains of autistic children who are non-verbal or severely limited verbally may respond more slowly to sound, according to findings presented at this year’s International Society for Autism Research conference in Montreal. Researchers believe this delay could interfere with language development. Tim Roberts, a professor of radiology at the Children’s Hospital of Philadelphia and the lead researcher in the study, believes the sound delay could help clinicians identify children in need of speech and language therapies.
More than ten years ago, Roberts and his colleagues discovered that autistic people experience delays in processing sound. According to a report by Spectrum News this month, this discovery was made using magneto-encephalography (MEG), a tool that detects the magnetic fields generated by the electrical activity of the brain. Brain responses called the M50 and the M100 occur about 50 and 100 milliseconds after a person hears a tone. Roberts and his team found that the M50 and the M100 were delayed by around 10 to 20 milliseconds in children with autism. Autistic children also experience a 50 second millisecond delay in a brain response called the Mismatch Field Latency (MMF), which peaks in response to unexpected speech sounds.
According to the Spectrum report, the new study by Roberts and his colleagues is the first study to check for these days among minimally verbal children with autism. For the study, Roberts and his team scanned 17 minimally verbal autistic children, 59 verbal autistic children, and 34 children as part of the control group. They also scanned six children who have an intellectual disability. All of the children were about 10 years old at the time of the scans. The researchers found that the minimally verbal group’s M50 response lagged behind the control group’s by about 13 milliseconds, while their M100 response lagged by about 40 milliseconds. The children with intellectual disabilities experienced similar delays.
Roberts believes this suggests the delay is driven by cognitive problems.
“This might be reflecting an inability of information processing,” Roberts was quoted as saying. “It’s showing up in language ability, but it’s actually just a global dysfunction.”
Other aspects of the study involved the children’s responses to unexpected syllables, which found significant lags in the children with autism compared with the control group. The researchers also measured a brain response called event-related desynchronization, which is a spike in brain waves that occurs when a person hears a word.
“If you can’t process sounds fast, if you can’t track the fact that the syllables have changed — it’s going to make you lousy at conversation,” Roberts observed.
For their next step, Roberts says he and his team plan to test brain responses in infants and toddlers with genetic mutations that put them at risk for autism or an intellectual disability. He hopes those responses will give doctors insight into children’s language and cognitive development.