Structural brain development between childhood and adulthood: Convergence across four longitudinal samples

TLDR

Longitudinal MRI studies have produced population models of brain development, yet inconsistencies in cortical grey and white matter trajectories raise doubts about sample comparability. The study aims to resolve these inconsistencies by conducting a comprehensive analysis across four diverse longitudinal datasets. Using four independent longitudinal samples (391 participants, 852 scans), the authors derived replicable models of gross structural brain development from ages 8 to 30 and examined the impact of adjusting for global cranial/brain size. The analyses revealed that intracranial and whole‑brain volumes continue to grow through adolescence, cortical grey matter peaks in childhood and declines thereafter, white matter rises until mid‑late adolescence before slowing, and that adjusting for cranial/brain size—particularly for sex differences—modifies developmental trajectories, thereby strengthening confidence in adolescent brain change patterns and informing best practices for future studies.

Abstract

Longitudinal studies including brain measures acquired through magnetic resonance imaging (MRI) have enabled population models of human brain development, crucial for our understanding of typical development as well as neurodevelopmental disorders. Brain development in the first two decades generally involves early cortical grey matter volume (CGMV) increases followed by decreases, and monotonic increases in cerebral white matter volume (CWMV). However, inconsistencies regarding the precise developmental trajectories call into question the comparability of samples. This issue can be addressed by conducting a comprehensive study across multiple datasets from diverse populations. Here, we present replicable models for gross structural brain development between childhood and adulthood (ages 8-30years) by repeating analyses in four separate longitudinal samples (391 participants; 852 scans). In addition, we address how accounting for global measures of cranial/brain size affect these developmental trajectories. First, we found evidence for continued development of both intracranial volume (ICV) and whole brain volume (WBV) through adolescence, albeit following distinct trajectories. Second, our results indicate that CGMV is at its highest in childhood, decreasing steadily through the second decade with deceleration in the third decade, while CWMV increases until mid-to-late adolescence before decelerating. Importantly, we show that accounting for cranial/brain size affects models of regional brain development, particularly with respect to sex differences. Our results increase confidence in our knowledge of the pattern of brain changes during adolescence, reduce concerns about discrepancies across samples, and suggest some best practices for statistical control of cranial volume and brain size in future studies.