Some autistic children don’t show traits of the condition until age 5 or later, new research suggests1. Others show a few mild features at age 3 but only later meet the criteria for diagnosis.
The findings suggest that autism traits are not always apparent by 24 months, the typical age for screening. As a result, efforts to bring down the average age of diagnosis, now at 4 years, can only go so far.
“There are some children who do get evaluated, sometimes multiple times, only to get diagnosed later,” says lead researcher Sally Ozonoff, endowed professor of psychiatry and behavioral sciences at the University of California, Davis. “This research is explanatory for those children.”
The results are based on following ‘baby sibs,’ or younger siblings of children with autism, who are at increased risk for the condition. But they should remind clinicians not to rule out autism in older children, even among the general population, experts say.