A child reads instructions on a
screen while his head is surrounded
by the MEG; © Children's Hospital
“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,” said study leader Timothy P.L. Roberts.
Like many neurodevelopmental disorders, in the absence of objective biological measurements, psychologists and other caregivers rely on clinical judgments such as observations of behaviour to diagnose ASDs, often not until a child reaches school age. If researchers can develop imaging results into standardised diagnostic tests, they may be able to diagnose ASDs as early as infancy, permitting possible earlier intervention with treatments. They also may be able to differentiate types of ASDs (classic autism, Asperger’s syndrome or other types) in individual patients.
Roberts and colleagues used magnetoencephalography (MEG), which detects magnetic fields in the brain, similar to the way electroencephalography (EEG) detects electrical fields. Using a helmet that surrounds the child’s head, the team presents a series of recorded beeps, vowels and sentences. As the child’s brain responds to each sound, non-invasive detectors in the MEG machine analyse the brain’s changing magnetic fields.
The researchers compared 25 children with ASDs, having a mean age of ten years, to 17 age-matched typically developing children. The children with ASDs had an average delay of eleven milliseconds (about 1/100 of a second) in their brain responses to sounds, compared to the control children. Among the group with ASDs, the delays were similar, whether or not the children had language impairments.
“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.”
COMPAMED.de; Source: Children's Hospital of Philadelphia