Little is known of the trajectory of grammar in neurodevelopmental disorders (NDDs) once adulthood and language maturity are reached. Yet, impairments in grammar are reported in children with both communication NDDs, such as Developmental Language Disorder (DLD), and other NDDs, including ASD and ADHD. In the present study, we review studies collected in the last ten years on the grammar of adults with NDDs. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were applied. Included studies assessed sentence-level grammatical abilities through quantitative experiments on adults with a diagnosis of a developmental disorder. Out of 1550 contributions, 29 were selected. The studies included in the review showed that individuals with NDDs show a language deficit when compared to healthy adults. However, a lack of a unified approach to investigations of grammar prevents comparisons on the nature of the language disorder across NDDs, consequently highlighting the existence of a gap in knowledge. This gap must be filled to the benefit of speech pathologists and, ultimately, their patients.
- neurodevelopmental disorder