A test that measures the electrical activity of the brain can distinguish children with autism from typical children as early as age 2, U.S. researchers say.

Dr. Frank H. Duffy and Heidelise Als of Boston Children's Hospital compared raw electroencephalogram data from 430 children with autism and 554 control subjects, ages 2-12.

The study, published in the journal BMC Medicine, found those with autism had consistent EEG patterns indicating altered connectivity between brain regions -- generally, reduced connectivity as compared with the control group.

While altered connectivity occurred throughout the brain in the children with autism, the left-hemisphere language areas stood out, showing reduced connectivity as compared with neurotypical children, consistent with neuroimaging research, the researchers said.

Duffy and Als focused on children with "classic" autism who had been referred for EEGs by neurologists, psychiatrists or developmental pediatricians to rule out seizure disorders and those with Asperger's syndrome, Fragile X or Rett syndrome.

"We studied the typical autistic child seeing a behavioral specialist -- children who typically don't cooperate well with EEGs and are very hard to study," Duffy said in a statement. "No one has extensively studied large samples of these children with EEGs, in part because of the difficulty of getting reliable EEG recordings from them." (c) UPI