Past-tense inflection of non-verbs: a potential clinical marker of developmental language disorder in Swedish children.

Aim: In this paper, we explore the performance of past-tense inflection of non-verbs (NVI) in children with developmental language disorder (DLD) and in typically developing controls, to investigate its accuracy as a clinical marker for Swedish-speaking children with DLD. Further, we investigate the relationship between NVI, nonword-repetition, and family history.

Methods: The sample consists of 36 children with DLD (mean age 9;5 years) and 60 controls (mean age 9;2 years).

Results: The DLD group performed significantly lower than the controls on the NVI task, with a large effect size of the difference (d = 1.52). Analysis of the clinical accuracy of NVI resulted in 80.6% sensitivity and 76.6% specificity. NVI was significantly and moderately associated with nonword-repetition in the controls, but not in the DLD group. A positive family history, 80.6% in the DLD group and 6.9% in the controls, was associated with lower performance on NVI. When controlling for group (DLD and controls), a non-significant association between family history and performance on the NVI task was found.

Conclusions: NVI is a potential clinical marker of DLD in Swedish school-aged children, but the current NVI task does not reach the level of being acceptable. Further development of the NVI task is warranted to improve its accuracy.