Early predictors of dyslexia in Chinese children: familial history of dyslexia, language delay, and cognitive profiles.

Background: This work tested the rates at which Chinese children with either language delay or familial history of dyslexia at age 5 manifested dyslexia at age 7, identified which cognitive skills at age 5 best distinguished children with and without dyslexia at age 7, and examined how these early abilities predicted subsequent literacy skills.
Method: Forty-seven at-risk children (21 who were initially language delayed and 26 with familial risk) and 47 control children matched on age, IQ, and mothers' education were tested on syllable awareness, tone detection, rapid automatized naming, visual skill, morphological awareness, and word reading at age 5 and subsequently tested for dyslexia on a standard Hong Kong measure at age 7.
Results: Of those with an early language delay, 62% subsequently manifested dyslexia; for those with familial risk, the rate of dyslexia was 50%. Those with dyslexia were best distinguished from those without dyslexia by the age-5 measures of morphological awareness, rapid automatized naming, and word reading itself; other measures did not distinguish the groups. In a combined regression analysis across all participants, morphological awareness uniquely explained word reading accuracy and rapid automatized naming uniquely explained timed word reading at age 7, with all other measures statistically controlled. Separate stepwise regression analyses by group indicated that visual skill uniquely explained subsequent literacy skills in the at-risk group only, whereas tone and syllable awareness were unique predictors of literacy skills in the control group only.
Conclusions: Both early language delay and familial risk strongly overlap with subsequent dyslexia in Chinese children. Overall, rapid automatized naming and morphological awareness are relatively strong correlates of developmental dyslexia in Chinese; visual skill and phonological awareness may also be uniquely associated with subsequent literacy development in at-risk and typically developing children, respectively.
(© 2010 The Authors. Journal of Child Psychology and Psychiatry. © 2010 Association for Child and Adolescent Mental Health.)