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Brain white matter predicts cognitive function by 1-2

A new kind of  brain imaging study could help identify cognitive problems and psychiatric disorders very early to help develop appropriate interventions.

A new study led by University of North Carolina (UNC) School of Medicine researchers concludes that microstructure patterns in white matter — present at birth — continue to develop after birth predicting cognitive function of children at ages 1 and 2.

"To our knowledge, this study is the first to measure and describe the development of white matter microstructure in children and its relationship to cognitive development from the time they are born until the age of 2 years."

John H. Gilmore MD, Director, Early Brain Development Program, UNC Department of Psychiatry and senior author of the study.

The study was published online on December 19, 2016 in the Proceedings of the National Academy of Sciences.

White matter is the tissue in the brain that contains axon fibers, which connect neurons in one brain region to neurons in another.

White matter is critical for normal brain function, but little is known about how it develops in humans or how it is related to cognitive skills in early childhood, including language development.

In the study, a total of 685 children received diffusion tensor imaging (DTI) scans of their brains. DTI is a technique using magnetic resonance (MRI) to capture the diffusion of water through tissue. It can identify white matter tracts in the brain, describe their organization as well as rate of maturation.

Study authors used these brain scans to investigate the microstructure of 12 white matter fiber tracts important to cognitive function, their relationship to developing cognitive function and their heritability — finding all 12 of the fiber tracts in the newborns were highly related to each other. By age 1, these fiber tracts had begun to differentiate themselves from each other, and had advanced even further by age 2.

The most interesting finding was that common relationships between white matter tracts at birth predicted overall cognitive development at age 1 and language development by age 2.

Therefore, it may be possible to use brain imaging at birth to better understand how a child's cognitive development will proceed in the first years of life.

Because the sample included 429 twins, authors of the study calculate this is a moderately inheritable predictive trait, suggesting genetics plays a role in its development.

"There is rapid growth of brain structure, cognition and behavior in early childhood, and we are just starting to understand how they are related.

"With a better understanding of these relationships, we ultimately hope to be able to identify children at risk for cognitive problems or psychiatric disorders very early — and come up with interventions that can help the brain develop in a way to improve function and reduce risk."

John H. Gilmore MD, Director, Early Brain Development Program, University of North Carolina Department of Psychiatry and senior author of the study

The integrity or microstructure of white matter as determined by diffusion tensor imaging (DTI) is related to cognitive function. Most studies focus on individual tracts, even though the microstructure of white matter tracts throughout the brain is highly correlated. In older adults, a common property of white matter predicts cognitive function, though it is not known if common factors are present in early childhood development or how they relate to cognitive function. Here, we found that DTI-based common underlying factors that emerge at this age are significantly related to cognitive abilities from birth to age 2 y. These findings indicate that the functional specialization of cognition and the anatomical differentiation of fibers cooccur in the neonatal and infant brain.

Previous studies indicate that the microstructure of individual white matter (WM) tracts is related to cognitive function. More recent studies indicate that the microstructure of individual tracts is highly correlated and that a property common across WM is related to overall cognitive function in adults. However, little is known about whether these common WM properties exist in early childhood development or how they are related to cognitive development. In this study, we used diffusion tensor imaging (DTI) to investigate common underlying factors in 12 fiber tracts, their relationship with cognitive function, and their heritability in a longitudinal sample of healthy children at birth (n = 535), 1 y (n = 322), and 2 y (n = 244) of age. Our data show that, in neonates, there is a highly significant correlation between major WM tracts that decreases from birth to 2 y of age. Over the same period, the factor structure increases in complexity, from one factor at birth to three factors at age 2 y, which explain 50% of variance. The identified common factors of DTI metrics in each age group are significantly correlated with general cognitive scores and predict cognitive ability in later childhood. These factors are moderately heritable. These findings illustrate the anatomical differentiation of WM fiber from birth to 2 y of age that correlate with cognitive development. Our results also suggest that the common factor approach is an informative way to study WM development and its relationship with cognition and is a useful approach for future imaging genetic studies.

In addition to Gilmore, authors of the study are Seung Jae Lee, Rachel J. Steiner, Yang Yu, Sarah J. Short, Michael C. Neale, Martin Styner, and Hongtu Zhu. All are at UNC except for Neale, who is in the Virginia Institute of Psychiatric and Behavioral Genetics at Virginia Commonwealth University.

Search words: factor analysis white matter DTI cognition heritability

This study was supported by grants from the National Institute of Mental Health (MH064065, MH 070890, RR025747 and MH086633), National Institute of Child Health and Human Development (HD053000) and the National Science Foundation (SES-1357666).
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Children's white matter is under study from birth through 2 years of age,
including white matter's relationship to intellectual development,

Image Credit: Public Domain



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