MRI reads early signs: Dyslexia diagnosis

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  • Published: Feb 1, 2012
  • Author: David Bradley
  • Channels: MRI Spectroscopy
thumbnail image: MRI reads early signs: Dyslexia diagnosis

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Children at risk of dyslexia show differences in brain activity on magnetic resonance imaging scans even before they start to learn to read, a study at the Children's Hospital Boston has found.

Dyslexia is a relatively common learning difficulty, which manifests itself as a spectrum of problems with reading, spelling and grasping phonics (the aural building blocks of words). The condition is poorly understood and while it does not reflect a problem with innate intelligence it can be sufficiently debilitating to prevent a child progressing as well in education as a child without the condition. Awareness of the condition is growing and diagnosis is becoming more accurate and can detect a likely problem earlier than before. The identification of pre-school children at risk of developmental dyslexia can often help avoid the educational difficulties and frustrations they face in school.

Now, an MRI method for highlighting children at greatest risk of having developmental dyslexia could be on the horizon thanks to researchers at the Children's Hospital Boston. The research is described in detail in the Proceedings of the National Academy of Sciences.

Developmental incidence

Developmental dyslexia, as opposed to dyslexia triggered by physical brain injury, is thought to afflict between 5 and 17 percent of all children. Moreover, around 1 in 2 children with a family history of the condition will most likely struggle with reading; they will experience poor spelling and have problems with decoding text and fluency in word recognition. Such children will commonly have problems with phonological awareness because they struggle to recognize and manipulate the underlying sound structures of words and so cannot successfully map the sounds of words to the written word.

Nora Raschle of the Laboratories of Cognitive Neuroscience and her colleagues carried out functional MRI imaging on 36 pre-school children (with an average age of 5.5 years) while they performed tasks requiring them to decide whether two words started with the same speech sound. The team developed a "spaceship adventure" game to help the children to keep as still as possible in the scanner!

The researchers found that during the phonological tests, those children known to have a family history of dyslexia displayed a lower metabolic activity in the junctions between the occipital and temporal lobes and the temporal and parietal lobes in the back of the brain compared to children matched for age, IQ and socioeconomic status who lacked the family history.

Metabolic performance

"We already know that older children and adults with dyslexia have dysfunction in the same brain regions," explains team leader Nadine Gaab. "What this study tells us is that the brain's ability to process language sounds may be deficient even before children have reading instruction."

It seems that greater activity in those brain regions in either the at-risk or control groups correlated well with better pre-reading skills, such as rhyming, knowing letters and letter sounds, knowing when two words start with the same sound, and being able to separate sounds within a word. However, the at-risk children showed no increase in activation of frontal brain regions, which has also been observed in older children and adults with dyslexia. The team says that this suggests that these regions become active only when children begin reading instruction, as the brain tries to compensate for other deficits.

"We hope that identifying children at risk for dyslexia around preschool or even earlier may help reduce the negative social and psychological consequences these kids often face," says Raschle. "Families often know that their child has dyslexia as early as kindergarten, but they can't get interventions at their schools," she says. "If we can show that we can identify these kids early, schools may be encouraged to develop programs."

The UK's National Health Service points out that, "The outlook for dyslexia is highly variable. Around 95% of children respond well to educational interventions and go on to make moderate to good progress with reading and writing." It adds that the other 5% continue to find reading and writing difficult. These children "will require more intensive support and long-term assistance."

"We didn't show yet that this can be used as a diagnostic tool," Gaab told us. Indeed, the method points to possible problems before the children start reading. However, she adds that, "We don?t know which of them will go on to develop DD."


The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

 Children at risk of dyslexia show differences in brain activity on magnetic resonance imaging scans even before they start to learn to read, a study at the Children's Hospital Boston has found.

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