Brain-intelligence relationships across childhood and adolescence: A latent-variable approach

The analysis of the relationships between cortical and intellectual development is a complex matter. Greater brain plasticity in brighter individuals has been suggested, but the associations between developmental cortical changes and variations in the general factor of intelligence (g) across time at the latent level have not been addressed. For filling this gap, here we relate longitudinal changes in g with developmental changes in cortical thickness and cortical surface area. One hundred and thirty-two children and adolescents representative of the population from the Pediatric MRI Data Repository completed the Wechsler Abbreviated Scale of Intelligence in three time points and MRI scans were also obtained (mean inter-registration interval ≈ 2 years, age range = 6.1 to 21.3 years). Longitudinal latent variable analyses revealed an increase in g scores amounting to a full standard deviation on average. Intelligence differences estimated at the latent level were significantly correlated related with cortical changes. Older individuals showed greater decrease in cortical values along with smaller increase in intelligence. Furthermore, thickness preservation in brighter individuals was observed at early adolescence (10-14 years).