By Todd Neale via MedPage Today
Children with autism follow many different developmental trajectories as they progress toward adolescence, researchers found.
Those who are high-functioning as children tend to make greater gains as they age compared with those who are low functioning around the time they’re diagnosed, according to Peter Bearman, PhD, of Columbia University in New York City, and colleagues.
But a small subset of children — 8% to 11% — show dramatic improvement in communication and social skills from low functioning to high functioning, the researchers reported online ahead of the May issue of Pediatrics.
“More work is needed to discover whether these longitudinal patterns will help us not only to understand the diversity of autism but also to better target interventions and improve treatment,” they wrote.
The prevalence of autism spectrum disorders is growing, with the latest estimate released by the CDC putting the rate of 1 in every 88 children by age 8.
However, despite the increased visibility of autism, little is known about the rate or timing of how affected children develop in terms of communication, social skills, and control of repetitive behaviors, according to Bearman and colleagues.
To explore the developmental trajectories, they examined data on children with autism who were born in California from 1992 to 2001, and who received a confirmed autism diagnosis by 2006. All were enrolled with the California Department of Developmental Services (DDS), which provides services for autistic disorder, but not other spectrum disorders unless there is another qualifying condition.
The analysis included 6,975 children, ages 2 to 14, who had least four evaluations completed by DDS staff.
The researchers looked at development in 3 dimensions:
- Social function
- Repetitive behaviors
They defined six common trajectories, ranging from low functioning to high functioning for communication and social function and from never to usually for repetitive behaviors.
There was variation between the trajectories in the degree of improvement among the children, particularly in the social function dimension.
In general, children who were high functioning in one dimension were likely to be high functioning in one of the other dimensions, although there was some independence of the three dimensions.
There was a unique subgroup of children — called “bloomers” — who started out with low functioning but progressed to high functioning by age 14. This pattern accounted for 7.5% of the children for the communication dimension and 10.7% for the social function dimension.
Unlike the communication and social function dimensions, the repetitive behavior dimension saw few children who either improved over time (just 8.1%) or declined over time (7.1%). The rest of the groups — no repetitive behaviors, daily behaviors, behaviors when stressed, and usually having repetitive behaviors — remained relatively stable over time.
Certain socioeconomic factors were associated with various developmental trajectories.
Children with high functioning tended to have mothers who were older, more educated, white, and less likely to be a Medicaid recipient. In contract, children with low functioning tended to have mothers who were younger, foreign-born, less educated, non-white, and more likely to be a Medicaid recipient.
The bloomers tended to not have an intellectual disability and to have more educated, non-minority mothers.
“Although we are unable to identify the specific mechanisms through which socioeconomic status affects trajectory outcomes, the intervening variables likely include home and neighborhood environments, quality and intensity of treatment, quality of education, the efficacy with which parents are able to advocate for their children with institutions providing services, and many other factors in various permutations,” the authors wrote.
They acknowledged some limitations of the study, including the use of symptom severity data that were collected for resource allocation and not diagnosis, and the possibility that autistic disorder was overdiagnosed because the DDS only provides services for these children and not other disorders on the spectrum.