Patterns of vulnerability of language in children with severe developmental language disorders

Language disordered children with receptive language problems have worse outcome and also more severe problems in other areas of language than children with isolated expressive problems according to “the hypothesis of hierarchical vulnerability” formulated by Bishop and Edmundson (1987). We studied ten children with specific and severe developmental language disorders (DLD) longitudinally and found that the hypothesis was tenable with regard to the predictions about outcome. We also found that among children in the phonologic-syntactic subgroup (Rapin and Allen, 1983), children with poor comprehension and poor lexical-semantic ability had the most severe problems of syntax. Phonological production at ages 5 or 6 was not correlated to phonological production at age 8. Oral motor function, however, turned out to be an important prognostic factor for phonological outcome. The present findings call for revised methodological routines and therapeutical priorities regarding children with severe DLD.