Longitudinal characterization of white matter maturation during adolescence

Abstract

Background: Late adolescence is comprised of considerable developmental transitions, though brain maturational changes during this period are subtle and difficult to quantitatively evaluate from standard brain imaging acquisitions. To date, primarily cross-sectional studies have characterized typical developmental changes during adolescence, but these processes need further description within a longitudinal framework. Method:To assess the developmental trajectory of typical white matter development, we examined 22 healthy adolescents with serial diffusion tensor images (DTI) collected at a mean age of 17.8 years and 16-months later. Diffusion parameters fractional anisotropy, and mean, radial, and axial diffusivity were subjected to whole-brain voxelwise time point comparisons using tract-based spatial statistics.Results: At follow-up, adolescents showed significant change (≥ 153 contiguous voxels each at p<.01) in diffusion properties, including in bilateral superior longitudinal fasciculi, superior corona radiata, anterior thalamic radiations, and posterior limb of the internal capsule. Overall, correlations with cognitive performances suggested behavioral improvement corresponding with white matter changes. Conclusion:These longitudinal DTI findings support continued microstructural change in white matter during late adolescence, and suggest ongoing refinement of projection and association fibers into early adulthood.

DTI Values in Key White Matter Tracts from Infancy through Adolescence

“…The relationship between changes in these diffusion properties and corresponding behavioral, cognitive, and sensorimotor modalities are still being uncovered. 2 Consistent with our findings, an intriguing idea is that these physiologic responses are the result of the environmental acquisition of more complex cognitive, executive, and visual spatial tasks that occur during childhood and adolescence, thus requiring the recruitment of more anterior structures. At present, the increases in integrity and organization of neurofilaments, microtubules, axonal diameter, layers of myelination, dendritic arborization and synaptogenesis, and structural WM fiber tract attenuation and coherence have been invoked as a cause of the observed increase in anisotropy, though a definitive answer has yet to be conclusively shown.…”

“…5,22,[33][34][35] The prevailing consensus in the field is that increases in FA are associated with a decrease in brain-water content and correlate with concomitant WM organization, myelination, and maturation. 2,4,8,18,21,22,29,36,37 In contrast, the decrease in MD values correlates with decreases in the volume of extracellular space, intracellular macromolecular concentration, and total brain-water content. 21,29 Recent studies by our research group 38,39 have shown that DTI changes are associated with myelin loss and cytopathologic disruption in an animal model of induced hydrocephalus.…”

“…Scanning parameters for DTI sequences were the same for all 202 participants and consisted of diffusion-weighted, single-shot spin-echo EPI in the axial plane with a b-value of 1000 s/mm 2 …”

Becoming Consistent: Developmental Reductions in Intraindividual Variability in Reaction Time Are Related to White Matter Integrity

“…From childhood to adult age, the brain undergoes dynamic structural changes (Giedd and Rapoport, 2010). FA increases and overall diffusivity decreases indicate maturation of WM integrity (Bava et al, 2010;Giorgio et al, 2010;Lebel and Beaulieu, 2011) and are believed to be related to developmental changes in myelin content, axon caliber and/or neurite density, and changes in gross fiber organization (Paus, 2010). There is evidence that DTI provides promising WM microstructural phenotypes related to cognitive development (Olson et .…”

Longitudinal Development of Human Brain Wiring Continues from Childhood into Adulthood

“…Two small-sample longitudinal DTI studies in adolescence showed diffusion changes in white matter over relatively short intervals of 1.5-2.5 years (Bava et al, 2010;Giorgio et al, 2010). However, evidence for early childhood and postadolescent longitudinal changes in key brain connections is still lacking.…”