Children's Brain Development Tied to Physical Fitness

Researchers have found a link between physical fitness and the brain in 9- and 10-year-old children: Those who are fitter tend to have a bigger hippocampus and perform better on a test of memory than their less-fit peers.

The new study, which used magnetic resonance imaging (MRI) to measure the relative size of specific structures in the brains of 49 child subjects, was published ahead of print August 21, 2010, in the online edition of the journal Brain Research. "This is the first study I know of that has used MRI measures to look at differences in brain between kids who are fit and kids who aren't fit,” said University of Illinois (Urbana-Champaign, IL, USA) psychology professor and Beckman Institute (Urbana-Champaign, IL, USA) director Dr. Art Kramer, who led the study with doctoral student Laura Chaddock and kinesiology and community health Prof. Charles Hillman. "Beyond that, it relates those measures of brain structure to cognition.”

The study focused on the hippocampus, a structure tucked deep in the brain, because it is known to be important in learning and memory. Earlier studies in older adults and in animals have revealed that exercise can increase the size of the hippocampus. A bigger hippocampus is associated with better performance on spatial reasoning and other cognitive tasks. "In animal studies, exercise has been shown to specifically affect the hippocampus, significantly increasing the growth of new neurons and cell survival, enhancing memory and learning, and increasing molecules that are involved in the plasticity of the brain,” Ms. Chaddock said.

Instead of relying on second-hand reports of children's physical activity level, the researchers measured how efficiently the subjects used oxygen while running on a treadmill. The physically fit children were "much more efficient than the less-fit children at utilizing oxygen,” Dr. Kramer noted. When they analyzed the MRI data, the researchers found that the physically fit children tended to have bigger hippocampal volume--approximately 12% bigger relative to total brain size.

The children who were in better physical condition also performed better on tests of relational memory--the ability to remember and integrate various types of information--than their less-fit peers. "Higher fit children had higher performance on the relational memory task, higher fit children had larger hippocampal volumes, and in general, children with larger hippocampal volumes had better relational memory,” Dr. Chaddock stated.

Further research indicated that a bigger hippocampus boosted performance on the relational memory task. "If you remove hippocampal volume from the equation,” Dr. Chaddock said, "the relationship between fitness and memory decreases.”

The new findings suggest that interventions to increase childhood physical activity could have an important effect on brain development, according to Dr. Kramer. "We knew that experience and environmental factors and socioeconomic status all impact brain development. If you get some lousy genes from your parents, you can't really fix that, and it's not easy to do something about your economic status. But here's something that we can do something about,” Dr. Kramer concluded

Related Links:
University of Illinois
Beckman Institute