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Brain Images Show Biological Basis of Dyslexia

When diagnosing dyslexia, schools often rely on IQ tests in their evaluation. However, a new study has found that there are great similarities in brain patterns between poor readers with typical IQs— those that traditionally qualify for special ed services—and poor readers with low IQ, who do not meet the standard for services.

Using brain imaging scans (functional MRI), researchers at the Stanford University School of Medicine studied brain activation processes of 131 children, ages 7 to 16 while they completed a simple reading task. The children were divided into three groups:

  • Typical readers with typical IQs
  • Poor readers with typical IQs
  • Poor readers with low IQs

The findings, recently reported in Medical News Today (MNT), showed that brain patterns were similar in both groups of poor readers and differed significantly from patterns exhibited by typical readers.

This study adds to the growing body of research that shows similar difficulties exist among poor readers, regardless of their cognitive ability, leading senior researcher, Fumiko Hoeft, MD, Ph.D, to conclude that “IQ should not be emphasized in the diagnosis of reading abilities.” According to the MNT article:

Hoeft noted that the results are timely. The Diagnostic and Statistical Manual of Mental Disorders, the standard diagnostic guide for mental illnesses and brain disorders, is currently being revised, and there is a proposal to change it so that IQ wouldn’t be taken into consideration when diagnosing dyslexia. (The new version, DSM V, will be released in 2013.) This work, she said, is the ‘first study reporting biological neuroimaging evidence to support’ that change.

Hoeft and her colleagues also point out that these and other findings indicate that “any child with a reading difficulty, regardless of his or her general level of cognitive abilities (IQ), should be encouraged to seek reading intervention.”

Stanford University Medical Center. (2011, September 30). “Brain Imaging Study Shows Physiological Basis Of Dyslexia.” Medical News Today. Accessed from

One Response to “Brain Images Show Biological Basis of Dyslexia”

  1. John Hayes Says:

    Many studies have been done in the past that evaluated dyslexia interventions with different IQ groups of dyslexics where the conclusions found that all the different IQ groups of dyslexics benefited the same.

    I wrote several articles prior to 2006 about dyslexia myths about IQ and other subjects that were based on well done older studies so this information hasn’t been new for years. The reason I bothered was because I thought it a shame that different groups of dyslexics were not being considered for dyslexia and therefore never evaluated to receive the needed intervention to be helped.Here is one example from 200 .

    It seems that for many years MRI studies have been considered the gold standard for dyslexia studies when in fact the information and results generally isn’t new . When you consider that the subjects used in MRI dyslexia studies are diagnosed by interviews and pen and paper tests as being dyslexic or not while MRI testing to identify individuals as being dyslexic or not is still in the future my opinion is that MRI studies are over rated as a primary source of information.

    MRI studies almost always say that there is hope that that MRI’s will be able to be used as a diagnostic tool for dyslexia at earlier ages but at the best they might some day be used to confirm a dyslexia diagnoses and will never be a screening tool for the general population. All the existing MRI machines already have a usage rate and are expensive to use. As a general screening tool they would have to test maybe 10 people to identify one dyslexic . That is just not going to happen when a few qualified people could administer and evaluate standard dyslexia tests to 60-90 children a day at pre-schools and get just as accurate results.

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