Participating in speech and language therapies for longer periods of time may help most autistic children speak their first words, a study suggests.
Autism spectrum disorder, which affects one in 31 children in the US, often leads to difficulties with speech, leaving many children nonverbal or learning how to speak far later than their neurotypical peers.
Autistic children with speech issues have long shown benefits from intensive therapies, verbal speech exercises and assistive devices during their early school years.
A new study suggests speech language therapies are not only effective, but two in three autistic children are likely to learn how to speak with them.
The researchers, from Drexel University in Philadelphia, looked at over 700 preschoolers with autism spectrum disorder who had received speech intervention therapies for anywhere from six months to two years. On average, the children spent about 10 hours per week in therapy.
Of the children in the study, two-thirds developed spoken language, while one-third remained nonverbal or made no progress.
The experts believe autistic children were able to improve their speaking due to therapies such as the Early Start Denver Model (EDSM), which focuses on play and building positive relationships to boost language.
Methods used also included Treatment and Education of Autistic and Related Communication Handicapped Children (TEACCH) therapy, which uses visual cues and organized spaces and schedules to enhance speech.
A study from Drexel University found most autistic children who were in speech therapies for at least six months improved their language skills (stock image)
The team believes that the duration of the therapy rather than the intensity was associated with better outcomes in nonverbal children. This means that instead of spending 20 to 40 hours per week in therapy for a shorter period of time, spending months or years with 10 hours per week may be more effective.
Dr Giacomo Vivanti, study author and associate professor and leader of Early Detection and Intervention at the AJ Drexel Autism Institute, said: ‘When parents ask me if their child should do these interventions to gain spoken language, the answer after doing this study is still yes.
‘What our study is telling us is that even when we’re implementing practices that are evidence-based, some children remain behind. So, we should carefully monitor the response of each child and see what to add or change to tailor therapy for the individual as needed.
The latest CDC data shows one in 31 US children have autism, an increase from about one in 150 in the early 2000s.
It’s unclear what exactly is behind a surge in autism diagnoses, but Department of Health and Human Services (HHS) Secretary Robert F Kennedy Jr has suggested environmental toxins like mold, pesticides, food additives, medications or ultrasounds could all be to blame.
Autism experts have also noted that doctors are getting better at spotting the condition, especially in previously overlooked groups like girls and adults, which could be behind the rise.
The Drexel study, published in 2025 in the Journal of Clinical Child & Adolescent Psychology, evaluated 707 autistic children between 15 months and five years old, with an average age of three years.
Children in speech therapies were enrolled in the programs for six months to two years.
They participated in therapies for about 10 hours per week.
Of the 707 participants, 216 were enrolled in ESDM, which relies on parents and therapists using play and joint activities to bond and improve language. Another 208 were in Naturalistic Developmental Behavioral Interventions, which are play-based with activities initiated by the child.
Another 197 were in the Early Intensive Behavioral Intervention (EIBI) group, which is typically a one-on-one therapy targeting social and daily living skills such as getting dressed.
The last group, which had 86 participants, was TEACCH, which focuses on organization, such as with visual schedules, and independence.
At baseline, the majority of participants, 66 percent, were considered ‘minimally speaking,’ meaning they could not combine words to form short phrases.
The team found that 66 percent of children who were not speaking at the start of the study went on to learn single words or advance in their language abilities by the end of their therapies.
Of those who were minimally speaking at baseline, 50 percent advanced to being able to combine words into phrases.
However, one-third of children who started out non-speaking were still non-speaking after two years. Additionally, half of the minimally speaking group did not advance.
The team found children who did not advance tended to be in therapy for shorter lengths of time, such as under six months, for more hours per day. Meanwhile, children who were in therapy for six months to two years were more likely to have language gains, the researchers said.
Children who were able to imitate sounds and actions more effectively at the start of the study also had a higher chance of advancing in their language.
Vivanti said: ‘Those nonspeaking prerequisites of communication may help create infrastructure for spoken language. Imitating what others are doing may help may them later to imitate what people are saying, and from there using language to express their thoughts.’
There were several limitations to the study, including only following the children for up to two years, but the team suggested it could lead to further, more comprehensive research.
‘Often scholars are weary about sharing intervention data and examine children who are not showing an optimal response to their interventions, especially for interventions that are already established as “evidence-based,”‘ Vivanti said.
‘This paper shows a willingness in the early intervention community to collaborate on data and learn more about how to help all children.’
