Summary: New research reports that approximately two-thirds of initially nonverbal children with autism develop spoken language after evidence-based early intervention. The study identifies key factors, such as intervention duration and motor imitation skills, that influence success.
Key facts
Success Rates: Approximately 67% of children with autism who were initially nonverbal developed spoken language after early intervention. Duration versus intensity: The study found that the total duration of therapy (months or years) was a more significant predictor of success than weekly intensity (hours per week). Critical skills: Children with stronger motor imitation skills, such as clapping or nodding, were more likely to acquire the language. Scope of the study: Researchers analyzed data from 707 autistic preschool children across several evidence-based intervention programs. Source: Drexel University
After receiving evidence-based early interventions, about two-thirds of nonverbal children with autism speak single words and about half develop more complex language, according to a new study led by researchers at Drexel University’s AJ Drexel Autism Institute.
The findings, published in the Journal of Clinical Child and Adolescent Psychology, offer vital information for improving the success rates of children who remain non-speaking or minimally speaking after therapy.
With one in 31 children in the United States diagnosed as autistic, and an estimated one-third of them nonverbal, language skills remain a primary goal for early childhood development. Children who do not learn spoken language beyond the preschool years are often at greater risk for disabilities later in life.
Duration over intensity
In the first large-scale study of its kind, the team analyzed data from 707 autistic preschoolers across multiple studies. These children completed several evidence-based early interventions (such as Early Start Denver Model and TEACCH) for at least 10 hours per week.
The researchers found that the duration of the intervention was more strongly associated with positive outcomes than the intensity.
“The researchers found that the duration of the intervention, rather than the intensity of the intervention, was associated with outcomes in nonverbal children,” the study authors noted.
This suggests that rather than cramming 20 to 40 hours of therapy into a single week, greater success could be achieved by extending therapy over a longer term, providing more opportunities to practice skills.
Monitoring and adjustment of therapy
Unsuccessful participants started with lower scores on measures of cognitive, social, adaptive, and motor imitation. However, the study emphasizes that the intervention factors are modifiable.
“When parents ask me if their child should do these interventions to improve spoken language, the answer after doing this study is still yes,” said Giacomo Vivanti, PhD, associate professor at Drexel’s Dornsife School of Public Health.
“What our study tells us is that even when we implement evidence-based practices, some children fall behind. Therefore, we must carefully monitor each child’s response and see what to add or change to adapt the therapy to the individual as needed.”
Vivanti emphasized that for some children, the “standard” version of an intervention is sufficient, while others may require a focus on preverbal skills critical to communication.
Motor imitation as a predictor
Consistent with previous studies, the researchers found that children who performed more motor imitations (such as clapping or nodding when asked) were more likely to acquire spoken language.
“Those non-speech communication prerequisites can help create an infrastructure for spoken language,” Vivanti explained. “Imitating what others do can help them later to imitate what people say and from there use language to express their thoughts.”
Despite differences in theoretical orientation among the various interventions studied, the specific type of intervention made little difference in language learning outcomes. The study represents a rare large-scale collaboration between autism research institutions to share data on children who do not show optimal responses to established interventions.
Editorial notes:
This article was edited by a Neuroscience News editor. Magazine article reviewed in its entirety. Additional context added by our staff.
About this autism research news
Author: Greg Richter
Source: Drexel University
Contact: Greg Richter – Drexel University
Image: Image is credited to Neuroscience News.
Original Research: Closed access.
“Proportion and profile of autistic children who do not acquire spoken language despite receiving evidence-based early interventions” by Giacomo Vivanti et al. Journal of Child and Adolescent Clinical Psychology
Funding: This work was funded by the National Institute on Deafness and Other Communication Disorders.
Abstract
Proportion and profile of autistic children who do not acquire spoken language despite receiving evidence-based early interventions
Aim
To estimate the proportion of autistic children who do not acquire spoken language despite receiving evidence-based early interventions and identify child and intervention characteristics associated with this outcome.
Method
We collected data from 707 autistic preschool children (M age = 30.6 months) who participated in evidence-based early intervention studies. We examined the proportion of children who remained non-speaking or minimally speaking after the intervention and analyzed predictors of language outcomes, including cognitive, social, and motor skills, as well as the duration and intensity of the intervention.
Results
Approximately two-thirds of the initially nonverbal children acquired single words and half developed phrase speech. Children who did not acquire spoken language had lower initial scores on cognition, social affect, and motor imitation. Longer intervention duration was associated with better linguistic outcomes, while intervention intensity (hours per week) was not.
Conclusion
While most children benefit from early intervention, a subgroup remains unspoken. Monitoring progress and adjusting intervention strategies, particularly duration and focus on preverbal skills such as imitation, is critical to supporting these children.
