Brain development
How does the brain's outer layer change during adolescence?
Open access · cc by · source: Europe PMC
During adolescence, the brain's outer layer shrinks in volume primarily because it becomes thinner, not because its surface area decreases.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Healthy adolescent development from late childhood through early adulthood is characterized by a widespread, continuous decrease in both cortical volume and cortical thickness.
Evidence for the claim as stated.
Cortical thinning, rather than changes in surface area, is the primary developmental driver behind the overall reduction of cerebral cortical volume during adolescence.
Evidence for the claim as stated.
Discoveries this paper informs or conflicts with
- The adolescent cortex loses volume mainly because it thins, not because it shrinks in area
This paper informs this development.
Study at a glance
- Design
- Cohort — Four independent longitudinal MRI samples (CPB, Pittsburgh, NCD, BrainTime) of typical cortical development
- N
- N=388 · Final datasets: CPB 30, PIT 73, NCD 76, BrainTime 209
- Population
- Typically developing children, adolescents, and young adults across four sites
- Outcome
- Longitudinal trajectories of cortical thickness, surface area, and volume from childhood to adulthood
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Inspect source passages
How does the brain's outer layer change during adolescence?
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four separate datasets used in the study
This study used four separate datasets: Child Psychiatry Branch (CPB), Pittsburgh (PIT), Neurocognitive Development (NCD), and Braintime (BT).
30 participants in the final Child Psychiatry Branch dataset
The final CPB, PIT, NCD, and BT datasets included 30, 73, 76, and 209 participants, respectively.
Key findings
The study revealed that cortical volume, thickness, and surface area all decrease continuously from late childhood through early adulthood. Cortical thinning was identified as the primary driver of the overall volume reduction, displaying robust positive correlations with volume changes ranging from 0.72 to 0.95. In addition, they mapped a complex spatial relationship between surface area and thickness changes, finding positive correlations in deep cortical folds but negative correlations on the outer ridges.
Methodology
The researchers tracked brain structural changes in 388 healthy participants aged 7 to 29 across four independent longitudinal study groups, analyzing a total of 854 MRI scans. They calculated year-over-year changes in three cortical measurements: total volume, outer surface area, and overall thickness. By processing all datasets with identical software and using non-linear curve-fitting models, they mapped and compared developmental trajectories across the different samples.
Limitations
Because this study relied on MRI scans, it cannot directly prove the underlying cellular processes, such as synaptic pruning or cellular myelination, that cause these structural changes. Additionally, the study used an accelerated longitudinal design that combined multiple age cohorts rather than tracking the exact same individuals all the way from age 7 to age 29. The findings are also limited to healthy, typically developing individuals, meaning they may not represent neurodivergent or clinical developmental pathways.
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