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Imaging May Help Identify a Biomarker of Autism

Study finds autistic children have delayed responses to auditory frequencies

FRIDAY, Jan. 15 (HealthDay News) -- Autistic children have right-hemisphere delays in their response to a range of auditory frequencies, suggesting abnormal maturation of the auditory system, according to a study published online Jan. 8 in Autism Research.

Timothy P.L. Roberts, Ph.D., from the Children's Hospital of Philadelphia, and colleagues used whole-cortex magnetoencephalography to compare the frequency dependence of superior temporal gyrus 50 msec (M50) and 100 msec (M100) neuromagnetic auditory evoked field responses in 17 typically-developing children and 25 children with autism spectrum disorders.

The researchers found that, while M50 latency and amplitude were similar in both groups, there was a significant average M100 latency delay of 11 msec in the right hemisphere of children with autism, even after accounting for age, intelligence quotient, and language ability. Only typically-developing children had the expected earlier M100 latencies in older children compared with younger children. The latency delay was most pronounced at 500 Hz in children with autism and, at a threshold of 116 msec, had a sensitivity of 75 percent, a specificity of 81 percent, and a positive predictive value of 86 percent.

"The M100 latency delay indicates disruption of encoding simple sensory information," Roberts and colleagues conclude. "Given similar findings in language impaired and non-language impaired autism spectrum disorder subjects, a right-hemisphere M100 latency delay appears to be an electrophysiological endophenotype for autism."

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