Levels of key brain chemicals predict children's reading ability

Reading-impaired young children have higher levels of the metabolites glutamate and choline in their brains, and these higher levels continue to be indicative of difficulties in developing typical reading and language skills, a Yale study has found. 

The study appears in the Journal of Neuroscience.

Although anatomical and functional brain networks involved in reading disabilities have been well characterised, the underlying chemical bases of these differences in reading development have been poorly understood.

This study is believed to be the first to examine neurochemistry in a longitudinal study of children during the critical period when they are considered "emergent readers," the age at which neurocircuits that support skilled reading and speaking are still developing.

The Yale team measured levels of glutamate, choline, and other metabolites in 75 children, aged 6 to 10, whose reading abilities ranged from what is considered impaired to superior.

The researchers conducted behavioral testing to characterize the children's reading, language, and general cognitive skills, and used MR spectroscopy to assess metabolite levels.

They found that children with higher glutamate and choline levels in their brains tended to have lower composite scores for reading and language.

In follow-up testing two years later, the same correlation still existed for initial glutamate levels.

Kenneth Pugh

"Reading disabilities affect significant numbers of children," said first author Kenneth Pugh, associate professor of linguistics and president and director of research in the Haskins Laboratories at Yale.

"Our findings suggest new pathways for research into the connection between genes, brain development, and behavioural outcomes in children who struggle with reading."

The researchers also note that higher glutamate and choline levels have been implicated in hyperexcitability in children, another possible factor in cognitive impairment.

Robert Fulbright

"Further research may show whether there is a chemical basis that contributes to learning deficits among the reading-disabled children," said senior author Robert Fulbright, also of the Haskins Laboratories, and associate professor of diagnostic radiology at Yale School of Medicine.

More Information: 'Glutamate and choline levels predict individual differences in reading ability in emergent readers' Journal of Neuroscience Mar 2014 - K.Pugh, R.Fullbright, et al.

Higher activity levels may protect children from stress

Children with lower levels of daytime physical activity (PA) have higher hypothalamic-pituitary-adrenocortical axis activity (HPAA) in response to psychosocial stress, suggesting that PA may help children cope with stressful situations, according to research published online March 7 in the Journal of Clinical Endocrinology & Metabolism.

Silja Martikainen, of the University of Helsinki, and colleagues conducted a cross-sectional study of 258 8-year-old children to evaluate whether PA levels affected HPAA activity and HPAA response to psychosocial stress. PA was measured using a wrist accelerometer.

Stressors included doing arithmetic and being assigned to tell a story to an audience.

The researchers found that, after exposure to everyday stressors, children with the highest levels of PA or vigorous PA showed very little, if any, increase in salivary cortisol levels when compared to more sedentary children in the lowest and intermediate PA groups.

"Our study shows that increased levels of PA are associated with decreased HPAA reactivity to stress in a community sample of 8-year-old children," the authors write.

"Although children with different levels of PA show similar diurnal patterns of salivary cortisol, the children with the lowest activity levels are more responsive to psychosocial stress. Consequently, PA may contribute to the psychological well-being of children by regulating their neuro-endocrine reactivity to stress."