HKU Bulletin October 2008 (Vol. 10 No. 1)

Getting to the Root of Reading Problems New research shows dyslexic brains differ depending on the language they speak T he theory that dyslexia may be a different neurological condition in readers of different languages has gained new ground with the latest study from our Laboratory of Brain and Cognitive Sciences. Researchers at the State Key Laboratory have shown, for the first time, that the brains of dyslexics differ depending on the language they speak. Previous research had found that Chinese children who suffer reading difficulties use different parts of the brain to westerners. But now, a team, led by Assistant Professor in the School of Humanities, Dr Siok Wai-ting, has compared dyslexic Chinese children to their English-language counterparts and found that their brains are structurally different. “Previous neuro-imaging studies have revealed that dyslexic readers of alphabetic languages have decreased grey matter volume in the posterior brain,” Siok explained. But to assess whether these abnormalities are universal, or culture-dependent, she and her team decided to study dyslexic Chinese children. “What we found is that in Chinese readers the posterior grey matter is unaffected, while the grey-matter volume in the left middle frontal gyrus region – which has been shown to play a part in Chinese reading and writing - is significantly smaller in dyslexic children than it is in normal subjects,” she said. The research, published in the Proceedings of the National Academy of Sciences , could have major implications for teaching and learning. “This region of the brain is also important for working memory, and possibly for mathematics,” she added. Dyslexia affects between seven and nine per cent of children in Hong Kong and up to 17 per cent globally. “Our findings suggest that dyslexia in different cultures may cause different biological disorders, in fact they may be different disorders completely, so we should not use the same treatment methods for both. “One implication suggests we should use different treatment methods for Chinese children. We cannot simply adopt western treatment methods for alphabetical reading.” The subjects were all children - 16 normal and 16 dyslexic. Their brain functions were compared to each other and then compared to previously-published findings. “A lot of earlier findings have suggested that the part of the brain affected in western children is responsible for letter sound conversion, it is also very close to the auditory cortex. For alphabetic readers, reading and listening are very closely related. “However, the region for Chinese is close to the region for motor skills. We also found that for Chinese children reading and writing may be more closely related. “Apart from the academic impact, there is also an emotional one to consider; dyslexic children may suffer low self-esteem, especially those with a high IQ which is common in dyslexic children. Reading skills are not related to IQ.” The team will now concentrate on two areas of research. “One is the diagnostic aspect of dyslexia to see if we can find some early measurement of dyslexia and, secondly, we want to look at what kind of treatment methods can be provided for children. “In Chinese children dyslexia is usually identified pretty late because of the nature of Chinese writing. It might not show up until the age of eight or nine. But alphabetic readers can be identified much earlier, possibly in pre-school. The sooner they are identified the better, so early identification is very important. The findings suggest that if we identify and treat a child early their chance of going on to read normally is much higher,” she said. Siok also intends to explore the nature of Chinese reading and of Chinese dyslexia as a whole. “It’s a very important topic,” she said. “The problem is very difficult to overcome using the current method. “And parents often think that dyslexic Chinese children are lazy, even though the child is intelligent. There is not much knowledge of dyslexia in Chinese society so there’s some misunderstanding about the problem, this can have a great impact on the child, emotionally, and on the child’s development academically.” Hopefully, the new findings will go some way to enlightening parents about the nature of dyslexia and the importance of seeking early diagnosis and treatment. 9 8 RESEARCH