Some autistic children don’t show traits of the condition until age 5 or later, new research suggests. 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.
…[Researcher Sally] Ozonoff and her colleagues recruited 746 children — 483 baby sibs and 263 controls — from three sites.
The team assessed the children with a standard diagnostic tool at age 3. They also used standard scales to score the children’s daily living skills and social abilities, and they asked parents to report concerns about their children’s behavior. They evaluated the children at least once more from age 5 to 9.
Of the 746 children, 99 were diagnosed with autism at age 3 and 185 were diagnosed with related conditions. However, another 14 children, including 1 from the control group, received an autism diagnosis after age 5.
Half of the late-diagnosed children scored well below the cutoff for an autism diagnosis at age 3, but their scores increased significantly at ages 5 to 9. The other half scored just below the autism cutoff at age 3, and their scores bumped up slightly in that time.
The results suggest that autism traits in some children become significantly more pronounced over time.
Read full, original post: Slow onset may explain late autism diagnosis in some children