An early symptom of autism might be found in a baby’s gaze, researchers reported Thursday.

Diagnosing autism as early as possible is of critical importance. Studies show the earlier therapy begins, the more likely the child can overcome the deficits linked to the brain disorder.

The new study, published online in the journal Current Biology, examined babies 6 months to 10 months of age who were at higher risk of developing autism because they had an older sibling with autism. Researchers from Birkbeck College, University of London, placed sensors on the scalp to register brain activity while the babies viewed faces. During the exam, the faces sometimes looked at the babies and other times looked away. This was key because earlier studies show that eye contact in babies is important to their social interaction and that children with autism tend to avoid eye contact.

The study found that babies who went on to develop autism had different brain activity during the eye-contact test compared with babies who did not develop autism. In other words, the babies destined to develop autism were already processing social information differently.

"At this age, no behavioral markers of autism are yet evident, and so measurements of brain function may be a more sensitive indicator of risk," a co-author of the study, Mark Johnson, said in a news release.

More studies will be needed to see if such a test could be widely used to assist in earlier diagnosis of children with autism.