Identifying linguistic markers of French-speaking teenagers with developmental language disorder : which tasks matter?

Abstract

Purpose:This research aimed to identify reliable tasks discriminating French-speaking adolescents with developmental language disorder (DLD) from theirpeers with typical language (TL) and to assess which linguistic domains repre-sent areas of particular weakness in DLD. Unlike English, morphosyntax has notbeen identified as a special area of weakness when compared with lexicose-mantics in French preschoolers with DLD. Since there is evidence that subject–verb number agreement is consolidated in later childhood, one might expectmorphosyntax to be a particular weakness and marker of French DLD only in(pre)adolescence.Method:We administered 20 subtasks that assessed linguistic and phonolo-gical working memory skills of two groups: 17 adolescents clinically identifiedas having DLD (M= 14.1 years) and 20 (pre)teens with TL (M= 12.2 years).Using robust statistics that are less affected by outliers, we selected the mostdiscriminating subtasks between our groups, calculated their optimal cutoffscore, and derived diagnostic accuracy statistics. We combined these subtasksin a multivariable model to identify which subtasks contributed the most to theidentification of DLD.Results:Seven subtasks were selected as discriminating between our groups,and three showed outstanding diagnostic accuracy: Recalling Sentences, a multi-word task assessing lexicosemantic skills, and a subject–verb number agreementproduction task. When combined, we found that the latter contributed the mostto our multivariable model.Conclusion:This study provides evidence that the most relevant markers toidentify DLD in French teenagers are tasks assessing lexicosemantics and mor-phosyntactic domains, and that morphosyntax should be considered an impor-tant area of weakness in French-speaking teenagers with DLD.