Brain Maturation in Adolescence and Young Adulthood: Regional Age-Related Changes in Cortical Thickness and White Matter Volume and Microstructure

TLDR

Structural MRI and diffusion tensor imaging have characterized cortical gray matter, white matter volume, and microstructure development in adolescence, but concurrent investigation of these aspects in the same sample is rare, leaving their interrelations unclear. The study aimed to delineate age‑related changes in cortical thickness, regional white matter volume, and diffusion characteristics, and to investigate their interrelationships during brain development. The authors examined 168 healthy participants aged 8–30 years using structural MRI and diffusion tensor imaging. Results revealed regional cortical thinning, white matter volume increases, and diffusion changes with age, with cortical thickness showing the strongest age association; however, cortical thinning could not be explained by underlying white matter maturation, and the measures were not redundant, suggesting that integrating all three provides a more comprehensive view of brain maturation.

Abstract

The development of cortical gray matter, white matter (WM) volume, and WM microstructure in adolescence is beginning to be fairly well characterized by structural magnetic resonance imaging (sMRI) and diffusion tensor imaging (DTI) studies. However, these aspects of brain development have rarely been investigated concurrently in the same sample and hence the relations between them are not understood. We delineated the age-related changes in cortical thickness, regional WM volume, and diffusion characteristics and investigated the relationships between these properties of brain development. One hundred and sixty-eight healthy participants aged 8–30 years underwent sMRI and DTI. The results showed regional age-related cortical thinning, WM volume increases, and changes in diffusion parameters. Cortical thickness was the most strongly age-related parameter. All classes of measures showed unique associations with age. The results indicate that cortical thinning in adolescence cannot be explained by WM maturation in underlying regions as measured by volumetry or DTI. Moderate associations between cortical thickness and both volume and diffusion parameters in underlying WM regions were also found, although the relationships were not strong. It is concluded that none of the measures are redundant and that the integration of the 3 will yield a more complete understanding of brain maturation.