Researchers at the University of Washington have found that anti-social behavior among girls and anxiety among both sexes triggers depression in early adolescence.
"Anti-social behavior has typically been viewed as a big problem among boys, so it tends to be ignored among girls," said James Mazza, a UW professor of educational psychology and lead author of the new study.
"Boys with early anti-social behavior typically go on to show more anti-social behavior while girls may turn inward with symptoms, morphing into other mental health problems such as depression eating disorders, anxiety and suicidal behavior during adolescence.
"When all the risk factors were analyzed, anti-social behavior and anxiety were the most predictive of later depression. It just may be that they are more prevalent in the early elementary school years than depression," he added.
He noted that depression and anxiety share a number of symptoms.
Mazza said that early adolescence is when the first episode of depression typically occurs and that's when it has been noted that gender difference occur, with more girls than boys experiencing depressive symptoms.
Children can be assessed at 6 and 7 years of age, but depression is not often recognized or diagnosed until the middle school years.
Children in this study were drawn from a larger project looking at the risks for health and behavior problems. More than 800 children participated in the depression study. Eighty-one percent were white and 54 percent were boys.
The research was published in the online edition of The Journal of Early Adolescence.