Brain size and intelligence

By HSC Staff Writer • Published: October 12th, 2006
Category: Health in a Heartbeat

The smartest kids in class and the sharpest executives in the boardroom aren’t necessarily carrying their vast knowledge around in extra-large brains.

Researchers says when it comes to intelligence, brains need not be super-sized.

What seems more important is how the brain grows.

Scientists from the National Institute of Mental Health used sophisticated brain scans and standardized intelligence tests to see how the brains of more than three-hundred children from age seven to their late teens developed.

The kids who scored highest on I-Q tests actually started out with relatively thin cortexes… the outer layer of the brain that helps us reason and make decisions.

As they grew, their cortexes thickened quickly, only to thin out again.

Children with average intelligence showed the same pattern, but they reached their peak cortical thickness at earlier ages and thinness at later ages.

When all is said and done, everyone’s cortex is about the same thickness, no matter their intelligence.

Scientists don’t know what happens in the brain during this process, but previous studies have shown brain development involves not just the growth of brain cells, but the pruning of unneeded ones.

Researchers suspect the successful removal of inefficient brain cells may have a bearing on how intelligent we ultimately become.

Fortunately, no matter how their cortexes grew, all the kids in the study were happy and healthy.

It seems for important things like emotional well-being and social adjustment, neither rate of growth nor size matters.