New research suggests that young children with autism experience dramatically different trajectories, with some seeing improvement in their symptoms by age 6.

About 11 percent of kids on the spectrum have less severe symptoms and are improving by the end of their first year of elementary school, according to findings published online this week in the journal JAMA Psychiatry. The vast majority of children with autism, however, have more significant symptoms and a more level trajectory at that point.

For the study, Canadian researchers followed 421 youngsters, tracking them at four points starting when they were newly diagnosed and culminating when the kids reached age 6.

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When they looked specifically at adaptive functioning — or daily living skills — about 20 percent of kids showed improvement while half remained stable over time and the remaining third of children demonstrated a decline in their abilities.

Children who were diagnosed at younger ages and those with better language and cognitive abilities at the outset were more likely to see improvements in adaptive functioning, the study found. Meanwhile, girls were more often in the group with less severe and diminishing symptoms.

Some children with more severe autism symptoms showed meaningful improvement in adaptive functioning, suggesting that autism symptoms and adaptive functioning skills need to be considered independently.

Researchers said their findings highlight the importance of individualized treatment approaches for kids with autism in order to maximize progress for each child.

“It is imperative that a flexible suite of interventions that target both autistic symptom severity and adaptive functioning should be implemented and tailored to each child’s strengths and difficulties,” the researchers wrote.