Reading-related cognitive deficits in developmental dyslexia, attention-deficit/hyperactivity disorder, and developmental coordination disorder among Chinese children

Abstract

MOST PAST research findings suggest that phonological deficit is unique to developmental dyslexia insofar as alphabetic languages are concerned. The present study investigated the existence of any similar unique reading-related cognitive deficits associated with developmental dyslexia in a nonalphabetic script, Chinese. The pattern of comorbidity among various developmental disorders was also examined. One hundred six Chinese children with different types of developmental disorders or learning difficulties, including developmental dyslexia (DYS), attention-deficit/hyperactivity disorder (ADHD), developmental coordination disorder (DCD), and borderline intelligence (BI) were tested on literacy, rapid-naming, phonological, orthographic, and visual processing skills. It was found that (a) the comorbidiry rates among these developmental disorders were high; (b) the DYS-only group was most impaired in rapid naming and orthographic processing and performed significantly worse than other "pure" groups; (c) the ADHD-only and DCD-only groups performed very closely to the average normal range in literacy and cognitive domains; and (d) the cognitive profile of the DYS+ADHD group resembled that of the DYS-only group, while that of the DYS+DCD group resembled some characteristics of both the "pure" groups. The authors conclude that rapid-naming deficit and orthographic deficit are unique marker deficits of developmental dyslexia in Chinese, while children with ADHD or DCD are less impaired in literacy and reading-related cognitive areas. Implications for educational and clinical practices are also discussed. © 2005 International Reading Association.