kitchen table math, the sequel: IQ & dyslexia

Wednesday, June 20, 2012

IQ & dyslexia

The Brain Basis of the Phonological Deficit in Dyslexia Is Independent of IQ

Although the role of IQ in developmental dyslexia remains ambiguous, the dominant clinical and research approaches rely on a definition of dyslexia that requires reading skill to be significantly below the level expected given an individual's IQ. In the study reported here, we used functional MRI (fMRI) to examine whether differences in brain activation during phonological processing that are characteristic of dyslexia were similar or dissimilar in children with poor reading ability who had high IQ scores (discrepant readers) and in children with poor reading ability who had low IQ scores (nondiscrepant readers). In two independent samples including a total of 131 children, using univariate and multivariate pattern analyses, we found that discrepant and nondiscrepant poor readers exhibited similar patterns of reduced activation in brain areas such as left parietotemporal and occipitotemporal regions. These results converge with behavioral evidence indicating that, regardless of IQ, poor readers have similar kinds of reading difficulties in relation to phonological processing.

The Brain Basis of the Phonological Deficit in Dyslexia Is Independent of IQ
Hiroko Tanaka, Jessica M. Black, Charles Hulme, Leanne M. Stanley, Shelli R. Kesler, Susan Whitfield-Gabrieli, Allan L. Reiss, John D. E. Gabriell and Fumiko Hoeft
Psychological Science
Vol. 22, No. 11 (NOVEMBER 2011) (pp. 1442-1451)
Page Count: 10


west bengal board syllabus said...

Dyslexia is a disease of not understanding the symbols and figures but IQ is a different thing.

K9Sasha said...

Dyslexia is a language disorder that manifests most obviously in reading. I can tell if someone has dyslexia by hearing them speak. Dyslexics have trouble processing sounds quickly and in the right order, so you hear things like "bretfast" (an adult friend of mine a few years ago), "rottwelder" (same friend), and "charateristics" (my 20 year old son). Dr. Sally Shaywitz explains more about this in her book Overcoming Dyslexia.

Katharine Beals said...

From what I've read (Maryanne Wolf and a few others) dyslexia seems to involve a combination of two core disabilities:
1. speech processing deficits (affecting phonemic awareness)
2. rapid naming deficits (affecting rapidity of letter identification).

I could imagine that rapid naming impairments might have some effect on IQ scores.

What's not clear to me is whether having just one of these two impairments results in dyslexia.

gasstationwithoutpumps said...

Dyslexia is a symptom, not the underlying disorder. It can be caused by many different underlying problems: visual, speech processing, naming, … .

A diagnosis of "dyslexia" is like a diagnosis of "fever". It tells you that there is a problem, but not what the cure is. There are fever-reducing drugs that address the symptom without curing the disease, and there are probably therapies for dyslexia that address the symptom without addressing the underlying problem. Sometimes that is all you can do, but if you can dig deeper and figure out what is causing the symptom, you may be able to find a more effective treatment.