Wednesday, February 12, 2020

Predicting Dyslexia in Children with Developmental Language Disorder

Alonzo, McIlraith, Catts, & Hogan (2019). Predicting dyslexia in children with developmental language disorder. Journal of Speech, Language, and Hearing Research, 63, 151-162.

This paper examines early predictors of reading ability in children with developmental language disorder (DLD) and children with typical language. Measures of phonological processing, including phonological awareness, are often used as predictors of later reading ability and dyslexia. However, children with DLD are known to have poor phonological processing in early school aged years, but not all children with DLD go on to have reading problems. Another early skill known to predict reading ability is letter identification. The aim of the present study was to examine how Grade 2 reading abilities in children with DLD and children with typical language are predicted by kindergarten phonological awareness and letter identification.

The study used a subset of data from 473 children, from a previous longitudinal study of 7218 children (cite). In kindergarten, the participants completed measures of expressive and receptive language, phonological awareness, and letter identification. In grade 2, children completed a measure of single word reading abilities. Participants were categorized into a DLD group and TD group based on their performance on the expressive and receptive language measures. Additionally, participants were categorized as having dyslexia if they scored below the 16th percentile on the reading task administered in grade 2. The authors used a number of regression analyses to examine how phonological awareness and letter identification predict dyslexia and reading ability in the DLD and typical language groups. In general, results for the DLD group showed that letter word identification was a strong predictor of grade 2 word reading and phonological awareness did not contribute to predicting unique variance. For the TD group, on the other hand, phonological awareness and letter identification predicted grade 2 reading, with the latter being a stronger predictor in poorer readers.

Overall, these findings suggest that letter identification is an early predictor in both children with DLD and children with typical language, however, the role of phonological awareness varies between the two groups. Although phonological awareness is a strong predictor of reading in children with typical language, it may not have the specificity or sensitivity to be used to predict reading and dyslexia in children with DLD, given their poor phonological processing abilities. Currently, most dyslexia screeners are focused on measures of phonological processing, which is likely to result in false positives in children with DLD. The authors suggest that screeners should include both phonological awareness and letter identification measures, as well as measures of early language skills such as sentence imitation, grammatical awareness, or comprehension for better early identification of DLD.

Blogger: Alex Cross is a M.Cl.Sc. and Ph.D. Candidate in Speech-Language Pathology, supervised by Dr. Lisa Archibald and Dr. Marc Joanisse.

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