Fitter kids are better at maths, researchers say
The thinning of grey matter is a normal process of child brain development.
"Grey-matter loss during child development is part of healthy maturation," said University of Illinois postdoctoral researcher Laura Chaddock-Heyman, who led the research
"The theory is that the brain is pruning away unnecessary connections and strengthening useful connections."
The study suggests that cardiorespiratory fitness contributes to this thinning process.
Previous studies have shown that grey-matter thinning is associated with better reasoning and thinking skills, Chaddock-Heyman said.
"We show, for the first time, that aerobic fitness may play a role in this cortical thinning," she said.
The analysis included 48 children, all of whom had completed a maximal oxygen-uptake fitness test on a treadmill. Half of the children (the more fit kids) were at or above the 70th percentile for aerobic fitness, and half (the less fit kids) were at or below the 30th percentile.
The researchers imaged the children's brains using MRI, and tested their maths, reading and spelling skills.