Which linguistic measures distinguish transient from persistent language problems in Late Talkers from 2 to 4 years? A study on Italian speaking children

Background: In spite of the large literature on Late Talkers (LTs) it's still unclear which factors predict outcome in children younger than 3 years old. Aims: To identify the early language characteristics of LTs whose outcome was either a transient delay or a Developmental Language Disorder (DLD). Methods and procedures: 50 LTs were assessed both by indirect and direct measures of expressive and receptive language at three time points between 2 and 4 years of age. Outcomes and results: At the first evaluation, all LTs had an expressive language delay; 61% also had delayed early syntactic comprehension. Three different linguistic outcomes emerged: children who caught up with their peers ("Late Bloomers") at age 3; children with slow language recovery ("Slow Learners") at age 4 and children at risk of DLD. The linguistic measures that differentiated the groups changed with age. By 28 months, impaired syntactic comprehension differentiated children at risk of DLD at 4 years of age, from the other two groups. By 36 months, the discrepancy between vocabulary size and age was larger in children with persistent language difficulties compared to both "Late Bloomers" and "Slow Learners". Expressive grammar differentiated the groups significantly by age 3 with difficulties in this domain still persisting in children with DLD at age 4. Conclusions: An early syntactic comprehension delay was a predictive index of DLD in LTs, suggesting the importance of evaluating this language component when assessing LT toddlers. Implications: LTs with receptive-expressive language delay around 24-30 months could benefit from an early language intervention.