Resolving the mystery of Chinese developmental dyslexia: in search of predictors and early markers.

Developmental dyslexia is a specific learning disability for which early identification and intervention are crucial. In alphabetic languages, phonological awareness and letter naming are well-established early markers of reading disorders. For developmental dyslexia in Chinese, a language that differs from alphabetic languages in multiple aspects, little is known about its early markers. Here, we report findings from a 2.5-year longitudinal behavioral study and a functional neuroimaging study designed to identify the neural underpinnings of predictors of Chinese reading disability. In Experiment 1, 237 Chinese children were assessed at age 5 on phonological awareness, morphological awareness, phonological memory (measured by digit span) and rapid automatized naming (RAN). Their reading performance was measured two and a half years later using a nationally standardized Chinese reading assessment. Forty children were identified as dyslexic and fifty-six as typical readers. For the two groups of children, we found that phonological memory and RAN were unique and reliable predictors of reading disorders, explaining significant variance after controlling for other factors. The analyses with all 237 participants showed the same pattern. In Experiment 2, we conducted a brain-wide association study in skilled readers to examine whether these two predictors were associated with activation in reading-related regions. We found that phonological memory and RAN were strongly associated with regions supporting Chinese reading. This research has demonstrated that phonological memory and RAN are early cognitive markers of Chinese dyslexia and, for the first time, has tried to pave the way for effective early intervention strategies for Chinese reading difficulties.