No link between Dyslexia and IQ

A new study that found no association between dyslexia and IQ calls into question the widespread practice of classifying children as dyslexic based on differences between their reading abilities and their IQ scores, researchers report.

This approach, called the discrepancy model, is used by many school systems in the United States to determine whether a student will be provided with specialised reading instruction.

But the researchers said their findings suggest that with the discrepancy model, children with dyslexia and lower-than-average IQ scores may not be classified as learning disabled and therefore would not be eligible for special reading help.

Dyslexia is a learning disability that affects a person's ability to read.

In this US National Institutes of Health-funded study, researchers used MRI to measure the brain activity of 131 students, aged 7 to 16, at schools in the Pittsburgh and San Francisco Bay areas.

The children were divided into three groups: those with typical reading and IQ scores; those with poor reading skills and typical IQ scores; and poor readers with low IQ scores.

Brain scans

The brain scans were conducted while the children looked at pairs of words and indicated whether they rhymed or did not rhyme. The results showed that children with dyslexia had the same patterns of brain activation as those without dyslexia, regardless of whether or not they had low IQ scores in relation to their reading abilities.

"These findings suggest there is little reason to rely on the discrepancy model in the classroom any longer," study author Dr Fumiko Hoeft, of Stanford University, said in an NIH news release. "Regardless of IQ, all children with dyslexia should be eligible for support in learning to read."

The study was recently published online in the Journal Psychological Science.

The findings "indicate that the discrepancy model is not a valid basis for allocating special educational services in reading," Brett Miller, director of the Reading, Writing and Related Learning Disabilities Program at the US National Institute of Child Health and Human Development, said in the news release.

"It follows that, whether they have high IQ scores or low IQ scores, children with great difficulty in learning to read stand to benefit from educational services to help them learn to read."

(HealthDay, November 2011)

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