Dyslexia, the language disorder that makes reading and spelling such a struggle, is more common in some cultures than others. Now researchers suggest that the neurological oddity responsible for some cases of dyslexia may be equally prevalent in different countries but that languages can either mask or expose the disorder.
Pity the poor speakers of English. Their language consists of just 40 sounds, but these phonemes can be spelled, by one count, in 1120 ways. French spelling is almost as maddening. Italian speakers, in contrast, must map 25 speech sounds to just 33 combinations of letters. Not surprisingly, Italian schoolchildren read faster and more accurately than do those in Britain. And about twice as many people fit a strict definition of dyslexia in the United States as in Italy.
Suspecting a connection, a group of researchers led by neurologist Eraldo Paulesu of the University of Milan Bicocca observed people's brain activity while they read. They compared British and French university students diagnosed with dyslexia with Italian students who showed the same pattern of slow reading and memory deficits typical of dyslexia, but who could read just fine. (Very few Italian university students have been diagnosed with dyslexia.) The researchers found the same pattern of activation in dyslexic students from all three countries: Compared to other students, they had less activity in a part of the brain known to be important for reading and spelling.
The study shows that "dyslexics share a common neurobiological substrate," even though they have very different degrees of difficulty with reading and spelling, says neuroscientist Guinevere Eden of Georgetown University in Washington, D.C. "The study is small, but it's the first of its kind, and [such studies are] very important to this field," she adds.