As part of a new study, researchers have linked participation in team sports to less depression in boys aged 9 to 11.Adult depression has long been associated with shrinkage of the hippocampus, a brain region that plays an important role in memory and response to stress. Now, the new research has linked participation in team sports to larger hippocampal volumes in children and less depression in boys ages 9 to 11."Our findings are important because they help illuminate the relationships between involvement in sports, a volume of a particular brain region and depressive symptoms in kids as young as nine," said Lisa Gorham, lead author of the study published in the Journal of Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.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, according to the study, which is forthcoming in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging."The findings raise the intriguing possibility that there is some added benefit of the team or structured components of sports, such as the social interaction or the regularity that these activities provide," said Deanna Barch, senior author on the study.While other studies have shown the positive impact of exercise on depression and the link with hippocampal volume in adults, this study is among the first to show that participation in team sports may have similar anti-depressant effects in preteen children.The results indicated that there was an association between sports involvement and hippocampal volume in girls, but unlike boys, no additional association with depression. This might mean that different factors contribute to depression in girls, or that a stronger association to sports involvement might emerge at a later developmental period for girls.It's important to note, wrote Barch and Gorham, that these results are correlational, not causational. 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 a 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 asserted.