The Effects of PROsyntax in Children with Developmental Language Disorder and Autism Spectrum Disorder: A Nonrandomized Controlled Trial.

Background: Children with autism spectrum disorder (ASD) and children with development language disorder (DLD) often experience syntactic impairments. It is of the utmost importance to implement evidence-based intervention at the earliest possible stage to mitigate the adverse effects of these difficulties. Internationally, several programs are supported by scientific evidence. In Portugal, there are currently only two intervention programs, one of which is PROsyntax. However, its effectiveness has not yet been established. Aim: This study aims to determine the effects of PROsyntax on expressive and receptive syntax in preschool-age children with syntactic impairments diagnosed with DLD or ASD. Methods and procedures: This study is a nonrandomized controlled trial with a nonprobabilistic convenience sample. Thirty-one children aged between 3 and 6 years were recruited and allocated into an experimental group (EG, intervention group) ( Outcomes and results: Statistically significant improvements were observed in the EG compared to the CG in both expressive (F Conclusions and implications: The findings provide preliminary evidence supporting the effects of PROsyntax in improving expressive and receptive syntactic skills in preschool-age children with ASD or DLD. These findings have important implications for clinical practice, suggesting that explicit interventions can yield significant gains in preschool-age children with syntactic impairment. However, the nonrandomized design, small sample size, and absence of long-term follow-up limit the generalizability of results. Further research is needed to confirm these effects and explore differential responses across diagnostic groups.