"There is a body of research around this that adds to its credibility," he said. "For example, girls tend to make more internalizing statements -- blame themselves a little more for things that happen -- in contrast to boys who tend to make more externalizing statements, [in other words] blame outside causes."
"It has long been known that girls are more prone to anxiety and depression during adolescence than boys," agreed Jonathan Sandoval, professor of education at the University of the Pacific's Benerd School of Education in Stockton, Cali. "This is a time when societal pressures and expectations impact young women negatively, and talking about their concerns with others is obviously better than keeping them to themselves."
But what might be the effect of co-rumination induced depression and anxiety? Some worried that such feelings might in turn spur even more co-rumination, leading adolescents into a vicious cycle of despair.
"The danger is when the discussion between these girls is negative and destructive and is lacking the discussion of effective coping," said Cynthia Thomae, crisis response chair of the Arizona School Counselors Association.
And some kids may be especially prone to this pattern.
"Anxious, depressed kids complain a lot in a way that is not effective in eliciting support, so that their complaints 'don't work,' leading to more demoralization," said Dr. John T. Walkup, associate professor of child and adolescent psychiatry at Johns Hopkins Hospital.
The exception to this rule is discussion designed to eventually lead to a solution to the problem at hand, which generally has the effect of sparing young worriers from undue anxiety and depression.
"I think what it brings to mind is the distinction between controllable stressors and uncontrollable stressors," study author Rose said.
There are certain things that kids can solve by ruminating over them, she said -- such as how to improve a C in math, or how to develop soccer skills good enough to make the team. But for other problems, such as relationship issues and other fixtures of adolescent life, the solutions are not as apparent.
"Girls tend to co-ruminate about stressors that they can't control," she said. "I think helping girls recognize the differences between what they can solve and can't solve is important."
Keeping the importance of a solution in mind could go a long way in staving off additional anxiety and depression.
"Parents do well to listen to their children and help them seek solutions -- and to encourage them to see all aspects of a situation, not just the negative," Okiishi of the University of Iowa said.
Johns Hopkins' Walkup added that parents and medical professionals would do well to be on the lookout for the traditional warning signs of depression and anxiety, rather than focusing on co-rumination.
"Ineffective complaining is sign of depression and anxiety rather than a major cause," he said. "Over time, ineffective complaining can add to the burden of depression as people fell more helpless and less well understood."
Meanwhile, parents of adolescents might do well to try to shake off their own anxiety when it comes to protecting their children from a mental health crisis.
"The most important thing is not to get too bent out of shape about your daughter being involved in one of these relationships, unless her ability to function in one way or another -- her grades, her sleeping patterns -- starts to deteriorate," said Dr. Redford Williams, director of the Behavioral Medicine Research Center at Duke University School of Medicine.
Emory's Kaslow agreed. "If it's a little anxiety, a little sadness, that's just part of normal life. It's part of growing up."