Unique brainwave patterns, spotted for the first time in autistic children, may help explain why they have so much trouble communicating, according to a study.

Unique brainwave patterns, spotted for the first time in autistic children, may help explain why they have so much trouble communicating, according to a study.

Using an imaging helmet that resembles a large salon hairdryer, researchers discovered what they believe are "signatures of autism" that show a delay in processing individual sounds.

That delay is only a fraction of a second, but if the delay occurs for each separate sound, the lag time can cascade into a major obstacle in speaking and understanding people, the researchers said.

The study authors believe this is what happens with autistic children, based on the brainwave patterns detected in school-age children in their study.

The preliminary results need to be confirmed in younger children, but researchers hope this technique could be used to help diagnose autism in children as young as one year old - at least a year earlier than usual. This could result in behaviour treatment beginning earlier.

Andrew Papanicolaou, director of the clinical neurosciences centre at Texas University, said the study makes a major contribution to autism research.

"It gives us a window through which we get a picture of some of the neurological conditions responsible for the peculiar behaviours in autism," said Mr Papanicolaou, who was not involved in the research.

Dr James McPartland, a Yale University autism researcher and also not involved in the study, called the results "preliminary, with promise". Whether the patterns found in the study exist in all autistic children is uncertain, but they're worthy of more study, he said.

Study results were prepared for release today at the Radiological Society of North America meeting in Chicago.

Finding biomarkers - such as the brainwaves - that could enable earlier diagnosis and treatment is the "holy grail" for autism scientists, Dr McPartland said. Now, doctors typically diagnose autism through parents' reports and by observing behaviours that often don't emerge until at least age two, he said.

The brainwave study used non-invasive technology called magnetoencephalography (MEG). It measures magnetic fields generated by electrical currents in brain nerve cells, and records brain activity in real time.

Researchers at Children's Hospital of Philadelphia had 64 autistic children aged six to 15 listen through headphones to a series of rapid beeps while under the helmet-like device, which recorded the brain's response to the sounds. Those brainwaves, shown as highlighted areas on an imaging screen, were compared with responses in a group of non-autistic children.

In autistic children, response to each sound was delayed by one-50th of a second.

"We tend to speak at four syllables per second," said Timothy Roberts, the study's lead author and the hospital's vice-chairman of research. If an autistic brain "is slow in processing a change in a syllable ... it could easily get to the point of being overloaded."

There is no cure for autism, but behaviour treatment and sometimes medication can lessen symptoms.

Mr Roberts, the study author, said the findings fit with a leading theory that suggests autism is "a disorder of connectivity in the brain".

MEG technology also has been used to map brain tumours and to evaluate epilepsy.