More people speak Chinese natively than any other language in the world. A full fourteen percent of the world’s population claim Putonghua as their primary language; only five percent claim English. If about one in five—a number commonly given by advocate groups—of those who speak Chinese suffer from dyslexia, that’s more than 190 million Chinese speakers who have it.

But how exactly does a Chinese speaker struggle with dyslexia? Instead of having difficulty reading and recognizing words, Chinese speakers with dyslexia have trouble recognizing and mapping meaning on to characters. The language becomes confusing and hard to learn.

But because English speakers and Chinese speakers use different parts of their brains when processing their respective language, the biological origins of dyslexia appear to be separate. If that’s true, dyslexia could be dependent on culture; it could be a different disorder depending on what language the speaker struggles with.

“People used to believe that children who learned to read an alphabetic language will have reading problems, and that children who learn to read Chinese won’t,” said Dr. Becky Chen-Bumgardner, a professor of pyschology at the University of Toronto.

“But that’s not true.”

A different problem

English is a phonetic language, meaning it has an alphabet that dictates how it sounds. But Chinese is based on written characters called logograms. Put simply, they are pictures, and the shape and strokes of the character convey meaning. About 10% of children struggle with dyslexia in any language, said Chen-Bumgardner.

When children learn Chinese, they spend thousands of hours looking at and memorizing these characters. There are 50,000 characters; it takes about 3,000 to read a newspaper, and a well-educated adult knows about 8,000 characters.

Those with dyslexia have difficulty learning the distinctions between all of the characters, attaching meaning to them, and learning how to pronounce them.

For a long time, it was assumed that dyslexia had a universal biological origin: the underlying cause of dyslexia was the same in India and in Tajikistan. But recent findings challenge that thesis. Li Hai-tan, at the University of Hong Kong, used functional MRIs to examine the brains of reading-impaired Chinese children.

He and his colleagues found that, just as learning and speaking English and Chinese required different parts of the brain, dyslexia was associated with different parts of the brain, depending on the language the learner struggled with. For Chinese dyslexics, there was a reduction of gray matter in the the front-middle part of the left brain.

A recent and separate study found that the “unique demands of the Chinese writing system” could lead to deficits in memory encoding and retrieval for somebody with dyslexia, exacerbating the difficulties with reading.

All of this seems to suggest that culture and language play a large role in how dyslexia manifests itself. “Reading problems are somewhat different among cultures,” said Chen-Bumgardner, “and the factors that cause the problems are somewhat different.”

So what does all of this mean for the future? Researchers don’t suggest that a child with reading difficulties in English will be able to pick up Chinese with ease: thirty percent of dyslexic children in English will be dyslexic in Chinese, said Chen-Bumgardner. (That number is 50% for English to Spanish.) And there are obvious situational and cultural barriers to switching languages.

But all of these findings could have important implications for treatments: by exercising both parts of the brain students may strengthen connections that could help them think of words and meanings in new ways.

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