Down syndrome (DS), or trisomy 21, is a genetic condition in which individuals have part or all of a third 21st chromosome.
Anecdotal evidence had already led people to believe that there might be something special about reading among people with Down syndrome. However, an extreme finding by Cossu and colleagues – that children Down syndrome read “in the absence” of phonological awareness (1983, p. 130) – sparked a debate that continues today.
Multiple articles have established a relationship between poorer reading ability and reduced phonological awareness (PA) readers with DS. However, considerable disagreement remains regarding specific PA task performance by these readers. In other words, is there equally poor performance in all types of phonological awareness tasks (e.g., rhyming, segmenting, blending, etc), are there specific PA tasks that are more challenging for DS readers, or is there heterogeneity PA task performance?
The earlier supposition that children with DS read without phonological awareness has been sufficiently refuted. Children with DS do seem to possess phonological skills, however, these abilities are markedly poorer than those exhibited by typically developing children matched by reading age. Further, their development of phonological awareness skills appears to progress at a slower rate than their ability to identify words (i.e., read high frequency sight words). Clearly, a hallmark feature of reading among children with Down syndrome is a relative strength in identifying both regular and irregular sight words and a deficit in reading non-words (a task that wholly relies on decoding skills).
Reading development for children with Down syndrome, therefore, does not appear to progress simply in a delayed manner when compared to typically developing readers. Rather, the process shows inconsistent and disordered development of PA skills in both the sequence of acquisition and distribution of ability. How does this knowledge inform clinical practice? The nature of phonological awareness in readers with Down syndrome has been investigated to tease apart the patterns of reading ability and specific underlying PA skills. However, there has been little research into the benefits of instructional methods aimed at improving specific PA skills. Some researchers recommend a combined approach that includes phonological awareness training while capitalizing on sight word reading. At least one study suggests that the phonological awareness of children with DS can improve with systematic and deliberate instruction. However, the advantage of this gain for decoding ability is not yet clear. Sight word identification has been shown to be used effectively by readers with DS. Several studies also showed that vocabulary development within experimental subjects has been comparable to typically developing controls. However, sight-reading for word identification will only take readers so far. Further research is necessary to determine what combination of approaches will best prepare children with DS to read at levels that more closely match their mental age and verbal language abilities.