Autism can be detected in infants as young as 2 months by tracking their eye movements, researchers say, marking the earliest signs of the developmental disorder ever observed.

Researchers found that between the ages of 2 and 24 months, children who were later diagnosed with autism looked less and less at other people’s eyes as compared to kids who did not develop the disorder.

The discovery, which is being heralded as a major development, could allow for earlier intervention and ultimately lead to better outcomes, experts say.

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“Autism isn’t usually diagnosed until after age 2, when delays in a child’s social behavior and language skills become apparent. This study shows that children exhibit clear signs of autism at a much younger age,” said Thomas Insel, director of the National Institute of Mental Health. “The sooner we are able to identify early markers for autism, the more effective our treatment interventions can be.”

The new finding comes from a study published Wednesday in the journal Nature that looked at 110 children from birth. Of them, 59 were considered to be at high-risk for autism because they had a sibling on the spectrum. The other children were deemed low-risk since they did not have any first, second or third degree relatives with autism.

Researchers used eye-tracking technology to assess the children 10 times between the ages of 2 months and 2 years. Subsequently, they compared data collected on children who were later diagnosed with autism to that from the other kids in the study who were not.

“We found a steady decline in attention to other people’s eyes, from 2 until 24 months, in infants later diagnosed with autism,” said Ami Klin, director of the Marcus Autism Center in Atlanta, who worked on the study.

Differences in eye contact between babies who later developed autism and those that did not began between 2 and 6 months and continued as the children became toddlers, the study found. By age 2, the children with autism focused on another person’s eyes about half as much as the typically-developing kids.

The level of decline in eye contact correlated with the severity of autism the children developed, the findings indicated.

Interestingly, the researchers said eye movements of children with autism seemed to be intact shortly after birth before beginning to decline. They said this suggests that intervention may be able to help children retain their abilities.

“This insight, the preservation of some early eye-looking, is important,” said Warren Jones of the Marcus Autism Center and Emory University and the study’s lead author. “In the future, if we were able to use similar technologies to identify early signs of social disability, we could then consider interventions to build on that early eye-looking and help reduce some of the associated disabilities that often accompany autism.”

While the findings offer promising leads for researchers and potential for new approaches to early intervention, Jones cautioned that parents are unlikely to pick up on these sorts of differences in eye contact.

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