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Intellectual ability and cortical development in children and adolescents

2006; Nature Portfolio; Volume: 440; Issue: 7084 Linguagem: Inglês

10.1038/nature04513

1476-4687

Philip Shaw, Deanna Greenstein, Jason P. Lerch, Liv Clasen, Rhoshel Lenroot, Nitin Gogtay, Alan C. Evans, Judith L. Rapoport, Jay N. Giedd,

Genetics and Neurodevelopmental Disorders

Here's a subject guaranteed to cause controversy: the relationship between intelligence, measured by IQ tests, and physical brain development in children and adolescents. A study that followed 307 typically developing subjects from childhood to adolescence (roughly between the ages of 6 and 19 years) now suggests that ‘brainy’ children are not cleverer by virtue of having more or less grey matter at any one age. Rather, intelligence is related to various aspects of the continuing process of cortical maturation. Specifically, the trajectory of change in the thickness of the cerebral cortex, not cortical thickness itself, relates to intelligence. More intelligent children demonstrate a particularly plastic cortex, with an initial accelerated and prolonged phase of cortical increase, which yields to equally vigorous cortical thinning by early adolescence. Children who are adept at any one of the three academic ‘R's (reading, writing and arithmetic) tend to be good at the others, and grow into adults who are similarly skilled at diverse intellectually demanding activities1,2,3. Determining the neuroanatomical correlates of this relatively stable individual trait of general intelligence has proved difficult, particularly in the rapidly developing brains of children and adolescents. Here we demonstrate that the trajectory of change in the thickness of the cerebral cortex, rather than cortical thickness itself, is most closely related to level of intelligence. Using a longitudinal design, we find a marked developmental shift from a predominantly negative correlation between intelligence and cortical thickness in early childhood to a positive correlation in late childhood and beyond. Additionally, level of intelligence is associated with the trajectory of cortical development, primarily in frontal regions implicated in the maturation of intelligent activity4,5. More intelligent children demonstrate a particularly plastic cortex, with an initial accelerated and prolonged phase of cortical increase, which yields to equally vigorous cortical thinning by early adolescence. This study indicates that the neuroanatomical expression of intelligence in children is dynamic.