A right-hemisphere latency delay of 1/100 of a second in the encoding of simple sensory information as demonstrated via magnetoencephalography (MEG), or the measuring of magnetic signals, may be considered an electrophysiological marker for autism spectrum disorders (ASD), according to research published Jan. 8 in Autism Research.
According to lead author Timothy Roberts, PhD, vice chair of radiology research at Children’s Hospital of Philadelphia, and colleagues, children with ASDs process sound and language a fraction of a second slower than children without ASDs. Measuring the change in magnetic fields within the brain of a child with suspected ASDs may serve as a standard way to detect this condition, which often goes undiagnosed until the child reaches school age.
The authors noted that the reason for late diagnosis of many neurodevelopmental disorders--which is currently estimated as affecting up to 1 percent of all U.S. children--is due to the absence of biological measurements, leading many caregivers and child psychologists to rely on behavioral observations to diagnose different types of ASDs.
The study recruited 25 children with ASDs and 17 typically developing children as a control group, with both groups having an average age of 10 years. The participants were fitted with a helmet that utilized whole-cortex MEG to detect magnetic fields in the brain, as they were exposed to a series of recorded beeps, vowels and sentences. The participants were asked to respond to each sound, while noninvasive detectors in the MEG machine analyze the brain’s changing magnetic fields. Left and right hemisphere activity was recorded by the researchers.
The children with ASDs had an average delay of 11 milliseconds, or approximately 1/100 of a second in their brain responses to the sounds compared to the control group, wrote the authors. In addition, the report found that in the ASDs group, latency delays were similar whether or not the children had auditory and/or speech deficits.
“This delayed response suggests that the auditory system may be slower to develop and mature in children with ASDs,” said Roberts. “An 11-millisecond delay is brief, but it means, for instance, that a child with ASD, on hearing the word ‘elephant’ is still processing the ‘el’ sound while other children have moved on. The delays may cascade as a conversation progresses, and the child may lag behind typically developing peers.”
The authors noted that upon further development of this technique, it may be possible to diagnose ASDs as early as infancy, allowing for possible earlier intervention and treatment.
Moreover, Roberts and colleagues believe that the differentiation between types of ASDs, including classic autism, Asperger’s syndrome and other types in individual patients may be possible in the future by way of this method.
“More work needs to be done before this can become a standard tool, but this pattern of delayed brain response may be refined into the first imaging biomarker for autism,” the researchers concluded.