Prevalence of Learning Disabilities Among Chinese Children, Adolescents, and Young Adults: Comorbidity, Age Trend, and Gender Differences

Abstract

Background: Early identification and prevalence estimates of learning disabilities (LDs) is critical to future intervention. However, in China, most studies were conducted in a single area and they only investigated children of a specific age group. There still lacks a large-sample study on the prevalence of LDs and their comorbidities in Chinese children, adolescents, and young adults. Methods: For the first time, this study examined the prevalence of LDs and their comorbidity rates and age trend and gender difference in 9236 Chinese children (6–11 years old, mean age = 9.55, standard deviation (SD) = 1.17), adolescents (12–17 years old, mean age = 14.03, SD = 1.65), and young adults (18–35 years old, mean age = 20.63, SD = 2.72). Computerized screening tests addressing arithmetic fluency (dyscalculia), reading fluency (dyslexia), and their comorbidity were administered in a large population-based sample of children (n = 3541, 1833 males and 1708 females), adolescents (n = 3641, 1928 males and 1713 females), and young adults (n = 2054, 1045 males and 1009 females). The prevalence of dyscalculia, dyslexia, and comorbidity were analyzed based on two cutoff criteria. Findings: The results showed that with -1 SD cutoff criteria, the prevalence rates of dyscalculia and dyslexia were 10.8% and 12.3%, respectively. The comorbidity rate of dyscalculia with reading disabilities was 34.8% and the comorbidity rate of dyslexia with arithmetic disabilities was 29.6%. Using -1.5 SD cutoff criteria, the prevalence rates of dyscalculia and dyslexia were 5.8% and 6.3%, respectively. The comorbidity rate of dyscalculia with reading disabilities was 24.3% and the comorbidity rate of dyslexia with arithmetic disabilities was 22.3%. When more stringent cutoff criteria were applied, the comorbidity rates of dyscalculia and dyslexia decreased. Among the three age groups, children showed the highest prevalence rate of dyscalculia and dyslexia. In addition, we observed a preponderance of males with dyslexia, whereas the gender ratio for dyscalculia was balanced among the three age groups. Interpretation: These findings suggested that the prevalence rates of dyscalculia and dyslexia in China are similar to that of other counties. The comorbidity rates of dyscalculia and dyslexia decreased as cutoff criteria became more stringent, suggesting that dyslexia and dyscalculia may have a common biological basis. Under the two cutoff criteria among the three age groups, the prevalence rate of dyslexia was higher than dyscalculia, which suggested that dyslexia affected a wider population than dyscalculia. Children were more vulnerable to dyscalculia and dyslexia compared to adolescents and young adults. Among the three age groups, gender differences existed in the prevalence rate of dyslexia; males were more likely to have dyslexia than females. Funding: This study is funded by the Natural Science Foundation of China (Grant No. 31700977, 31671151), Natural Science Foundation of Beijing (Grant No. 5212004), The 111 Project (Grant No. BP0719032), Advanced Innovation Center for Future Education (Grant No. 27900-110631111). Declaration of Interest: We declare no competing interests. Ethical Approval: The study design was approved by the State Key Laboratory of Cognitive Neuroscience and Learning at Beijing Normal University and the school principals.