A small number of children with severe autism "bloom" over time and progress to a high-functioning state, and a new study may reveal part of the reason this happens.
In most cases, children with autism who show severe symptoms at diagnosis improve very little as they age, while those who are least impaired improve more rapidly in their social and communication skills, the study showed.
However, about 10 percent of autistic children are so-called bloomers, the researchers said, and the study showed that one factor that distinguished these children was higher socioeconomic status. Bloomers tended to have white mothers with more education.
This suggests that the children's "blooming" is likely due, at least in part, to better access to high-quality, intense treatments, the researchers said.
"These socioeconomic disparities suggest that equal access to early interventions and services for less advantaged children is going to be really vital," said study researcher Christine Fountain, of Columbia University in New York City.
The study is published today (April 2) in the journal Pediatrics.
Fountain and colleagues analyzed records from nearly 7,000 children with autism between ages 2 and 14 in California. The children had at least four years of records of that described the severity of their autism symptoms.
The researchers found the children fell into six groups that were related to their development over time: high-functioning children, bloomers, medium-high functioning, medium functioning, low-medium functioning and low functioning.
Most of the children experienced at least some improvements in their communication and social skills over time, but children who were high functioning to begin with tended to improve more rapidly than children in the other groups.
For instance, on a test of communication skills with a maximum score of 100, those in the high-functioning group progressed, on average, from a score of about 50 at age 3 to a near-perfect score at age 14. In contrast, children in the low-functioning group progressed from a score of about 15 to about 20.
Bloomers progressed from a score of about 20 to about 80.
The most rapid improvements were typically seen before age 6, the researchers said.
The fact that bloomers' progression was tied to their socioeconomic status indicates that whatever factors are behind the cause of autism are not the only things driving a child's development.
More research is needed to understand what puts children with autism on a "blooming" path, and whether anything can be done to get them there, Fountain said.
Pass it on: About 10 percent of autistic children progress from severely affected to high functioning.