Frequent ear infections and waking up multiple times per night are among a growing list of potential early signs of autism, new research suggests.

Kids who were later diagnosed with the developmental disorder were more likely to have trouble sleeping at 9-months-old, according to findings published in the Journal of Early Intervention. Such children also had a greater number of ear infections than their typically-developing peers.

For the study, researchers compared data on about 100 children with autism to that of typically-developing kids who were part of the federal government’s Early Childhood Longitudinal Study, which tracked the development of 14,000 children born in 2001 from birth until kindergarten.

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At age 2, the study found that kids who were later diagnosed with autism scored lower on measures of communication, motor skills and social interaction. They were also more likely to “tune out” from activities, had difficulty re-engaging and needed longer to calm down when they became upset, researchers said.

“Different specialists who work with children with ASD are each focused on specific problems, but this research gathers all those pieces of information together and provides a much bigger picture,” said Laurie Jeans, a professor of early childhood education at St. Ambrose University in Iowa who led the study.

The findings add to evidence that autism can be reliably diagnosed at age 2. At present, however, most children are not diagnosed until after age 4, according to the U.S. Centers for Disease Control and Prevention.

“The sooner that you can catch some of these behaviors and intervene, the better their chances for developing good skills and being able to participate in school, academically and socially,” said co-author Rosa Milagros Santos Gilbertz of the University of Illinois.