According to a study published by Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, involvement in sports is related to greater hippocampal volume in both boys and girls, and is related to reduced depression in teenagers (the hippocampus is a brain region that plays an important role in memory and response to stress).
“Our findings are important because they help illuminate the relationships between involvement in sports, volume of a particular brain region and depressive symptoms in kids as young as nine,” says Lisa Gorham, lead author of the study and a senior majoring in cognitive neuroscience at Washington University in St. Louis.

These relationships were particularly strong for children participating in sports that involved structure, such as a school team, a non-school league, or regular lessons, as compared to more informal engagement in sports.
The findings raise the intriguing possibility that there is some added benefit of the team or structured component of sports, such as the social interaction or the regularity that these activities provide, says senior study author Deanna Barch, chair of the psychological and brain sciences department in the School of Arts & Sciences and professor of psychiatry at the Washington University School of Medicine in St. Louis.

Researchers based the study on a nationwide sample of 4,191 children ages 9-11 years from the Adolescent Brain and Cognitive Development Study. Parents provided information on their child’s participation in sports and other activities and on depressive symptoms. Brain scans of the children provided data on their bilateral hippocampal volume.
This study is among the first to show that participation in team sports may have similar antidepressant effects in preteen children.

It could be that participating in sports leads to increased hippocampal volume and decreased depression, or it could be that children who are more depressed are less likely to engage in sports and also have smaller hippocampal volume. Either scenario could have important implications for understanding childhood depression.

“The fact that these relationships were strongest for team or structured sports suggests that there might be something about the combination of exercise and the social support or structure that comes from being on a team that can be useful at preventing or treating depression in young people,” Gorham says. “The findings raise intriguing possibilities for new work on preventing and treating depression in children. ”