Williams Syndrome: PET Brain Scans Provide insight

A peek inside the minds of hypersocial people with Williams syndrome has revealed how the genetic disorder affects the brain.

People with Williams syndrome are known for their friendliness, although this tends to be coupled with heightened anxieties.

You can contact the UK Williams Syndrome association, here

Mbemba Jabbi at the National Institutes of Health in Bethesda, Maryland, and colleagues studied MRI scans of 14 people with the syndrome. They found that the insula, a brain region involved in emotion, was smaller than in 23 people without the syndrome.

When Jabbi's team used PET scans to examine the insula in more detail, though, they found that one area of the right insula was larger in people with Williams syndrome. Those with more extreme personality differences had more grey matter here.

The findings could help predict how social symptoms of the syndrome might develop, says Debbie Riby at Newcastle University, UK.

However, the people who participated in the study have a normal IQ, which is typical of only a small percentage of those with Williams syndrome, she says.

Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1114774109

A tractography study in dyslexia: neuroanatomic correlates of orthographic, phonological and speech processing

Diffusion tensor imaging tractography is a structural magnetic resonance imaging technique allowing reconstruction and assessment of the integrity of three dimensional white matter tracts, as indexed by their fractional anisotropy.

It is assumed that the left arcuate fasciculus plays a crucial role for reading development, as it connects two regions of the reading network, the left temporoparietal region and the left inferior frontal gyrus, for which atypical functional activation and lower fractional anisotropy values have been reported in dyslexic readers.

In addition, we explored the potential role of the left inferior frontal-occipital fasciculus, which might connect a third region of the reading network, the left ventral occipitotemporal region with the left inferior frontal gyrus.

In the present study, 20 adults with dyslexia and 20 typical reading adults were scanned using diffusion tensor imaging, and the bilateral arcuate fasciculus and the left inferior fronto-occipital fasciculus were delineated.

Group comparisons show a significantly reduced fractional anisotropy in the left arcuate fasciculus of adults with dyslexia, in particular in the segment that directly connects posterior temporal and frontal areas.

This fractional anisotropy reduction might reflect a lower degree of myelination in the dyslexic sample, as it co-occurred with a group difference in radial diffusivity.

In contrast, no significant group differences in fractional anisotropy were found in the right arcuate fasciculus or in the left inferior fronto-occipital fasciculus.

Correlational analyses (controlled for reading status) demonstrated a specific relation between performance on phoneme awareness and speech perception and the integrity of left arcuate fasciculus as indexed by fractional anisotropy, and between orthographic processing and fractional anisotropy values in left inferior fronto-occipital fasciculus.

The present study reveals structural anomalies in the left arcuate fasciculus in adults with dyslexia. This finding corroborates current hypotheses of dyslexia as a disorder of network connections.

In addition, our study demonstrates a correlational double dissociation, which might reflect neuro-anatomical correlates of the dual route reading model: the left arcuate fasciculus seems to sustain the dorsal phonological route underlying grapheme–phoneme decoding, while the left inferior fronto-occipital fasciculus seems to sustain the ventral orthographic route underlying reading by direct word access.

Access the Full Scientific Paper here at BRAIN: A journal of Neurology - A tractography study in dyslexia: neuroanatomic correlates of orthographic, phonological and speech processing

Dyslexia: MRI Brain Scans Spot Early Signs

Instead of waiting for a child to experience reading delays, scientists now say they can identify the reading problem even before children start school, long before they become labeled as poor students and begin to lose confidence in themselves.

Although typically diagnosed during the second or third grade of school - around age 7 or 8 - a team from Children's Hospital Boston said they could see signs of the disease on brain scans in children as early as 4 and 5, a time when studies show children are best able to respond to interventions.

"We call it the dyslexia paradox," said Nadine Gaab of the Laboratories of Cognitive Neuroscience at Children's, whose study was published in Proceedings of the National Academy of Sciences.

Gaab said most children are not diagnosed until third grade, but interventions work best in younger children, hopefully before they begin to learn to read.

"Often, by the time they get a diagnosis, they usually have experienced three years of peers telling them they are stupid, parents telling them they are lazy.

We know they have reduced self esteem. They are really struggling," Gaab said in a telephone interview.

Her study builds on an emerging understanding of dyslexia as a problem with recognizing and manipulating the individual sounds that form language, which is known as phonological processing.
In order to read, children must map the sounds of spoken language onto specific letters that make up words. Children with dyslexia struggle with this mapping process.

"The beauty is spoken language can present before written language so people can look for symptoms," said Dr. Sally Shaywitz, a director of the Center for Dyslexia and Creativity at Yale University.

Signs of early dyslexia might include difficulty with rhyming, mispronouncing words or confusing similar-sounding words.

"Those are all very early symptoms," Shaywitz said.

Dyslexia affects roughly 5 percent to 17 percent of all children and up to 1 in 2 children with a family history of the disorder will struggle with reading, have poor spelling and experience difficulty decoding words.

In her study, Gaab and colleagues scanned the brains of 36 preschool children while they did a number of tasks, such as trying to decide if two words start with the same sound.

They found that during these tasks, children who had a family history of dyslexia had less brain activity in certain regions of the brain than did children of similar ages, intelligence and socioeconomic status.

Older children and adults with dyslexia have dysfunction in these same areas of the brain, which include the junctions between the occipital and temporal lobes and the temporal and parietal lobes in the back of the brain.

Gaab said the study shows that when children predisposed to dyslexia did these tasks, their brains did not use the area typically used for processing this information. This problem occurred even before the children started learning to read.

"The important point of this paper is it shows the need to look for signs of dyslexia earlier," said April Benasich, director of the Carter Center for Neurocognitive Research at Rutgers, the State University of New Jersey, who was not part of the study.

Benasich studies language processing in even younger children - babies who have a family history of learning disorders.

"There is evidence to suggest that what is thought to be reading failure is there before the kids fail," she said.

Gaab said her study is too small to form the basis of any test for dyslexia but her team has just won a grant from the National Institutes of Health to do a larger study.

Ultimately, she hopes parents will be able to go to their pediatrician and ask for their child to be assessed.

"Families often know that their child has dyslexia as early as kindergarten, but they can't get interventions at their schools," she said in a statement.

"If we can show that we can identify these kids early, schools may be encouraged to develop programs," she said.