Researchers found the earliest-known signs of autism that occur within the first few months of life.

The researchers followed babies from when they were born to three years of age in order to identify the earliest signs of autism, an Emory Health Sciences news release reported.

"By following these babies from birth, and intensively within the first six months, we were able to collect large amounts of data long before overt symptoms are typically seen," Warren Jones, Ph.D., lead author on the study, said.

The team used eye-tracking technology to see what the babies were looking at. After the three year period they compared data between the babies that had been diagnosed with autism and those who had not.

"We found a steady decline in attention to other people's eyes, from [two] until 24 months, in infants later diagnosed with autism," co-investigator Ami Klin, Ph.D., director of Marcus Autism Center said. "First, these results reveal that there are measurable and identifiable differences present already before [six] months. And second, we observed declining eye fixation over time, rather than an outright absence. Both these factors have the potential to dramatically shift the possibilities for future strategies of early intervention."

The researchers said special equipment would be required to pinpoint the early signs, and they would not be visible to the naked eye.

"To be sure, parents should not expect that this is something they could see without the aid of technology," Jones said. "And they shouldn't be concerned if an infant doesn't happen to look at their eyes at every moment. We used very specialized technology to measure developmental differences, accruing over time, in the way that infants watched very specific scenes of social interaction."

When babies are so small they cannot yet physically interact with the world around them they tend to explore by looking around intensely. This is extremely important for brain growth.

The study showed that while infants who develop autism have a decline in eye contact around the two to six month marker, it is not entirely absent.

Researchers believe if the signs of autism were discovered earlier, more therapy could be administered to encourage eye contact.

The team also found the babies that had the quickest decline in eye contact generally had the highest levels of disability later in life.

"The genetics of autism have proven to be quite complex. Many hundreds of genes are likely to be involved, with each one playing a role in just a small fraction of cases, and contributing to risk in different ways in different individuals," Jones said. "The current results reveal one way in which that genetic diversity may be converted into disability very early in life. Our next step will be to expand these studies with more children, and to combine our eye-tracking measures with measures of gene expression and brain growth."