Children who exhibit signs of autism early on are generally better off long-term than those whose developmental skills plateau or regress, according to the largest study yet to look at regression in those on the autism spectrum.

The findings reported online this month in the Journal of Autism and Developmental Disorders come from an analysis of data provided by nearly 3,000 parents of children with autism to the Interactive Autism Network, or IAN, an online research effort. Researchers looked at factors such as the severity of a child’s diagnosis, when they achieved milestones like saying their first words and the level of educational supports a child received.

Children who regressed — or lost social, speech or cognitive skills they previously had acquired — were more likely to have severe autism and exhibit difficulty developing conversational speech. They also often needed more educational supports as compared to those who were merely slow to attain skills or whose skill level hit a plateau, researchers report.

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Similarly, children whose skill level plateaued were more likely to receive a severe autism diagnosis and need more supports than children who were delayed from the start.

“Children who plateau or regress have a later manifestation of autism, but when it manifests it devastates their development,” said Paul Law, an author of the study and director of the IAN project at the Kennedy Krieger Institute.