As a graduate student in developmental psychology at the University of Illinois, Amanda Rose studied girls’ and boys’ friendships. It was already well-known through research — not to mention by anyone who has ever been a boy or a girl — that girls in general talked more with friends and shared more personal information than boys did. At that time, about 15 years ago, it was also generally believed that this was a positive aspect of girls’ friendships, because those habits lead to closer and more intimate friendships.

But Rose, now a professor of psychology at the University of Missouri, saw something else going on. “Through my own experiences and my experiences watching girls talk in observational studies, I noticed that sometimes they seemed to get ‘stuck’ talking about problems. They weren’t doing other things as compared to boys who, in one study of kids on the playground, would engage in a lot of other activities, like sports and games,” she says. “Also, these girls seemed close to each other but kind of sad, too.”

[See: Am I Just Sad — or Actually Depressed?]

She pondered how these girls’ behaviors matched up with a well-documented psychological construct called rumination. Rumination refers to over-thinking about problems or bad feelings and is a common feature of depression. “It refers to thoughts that go through a person’s mind over and over again, without there being any closure,” says Dr. James Potash, professor of psychiatry and behavioral sciences and the department director and psychiatrist-in-chief at Johns Hopkins Medicine. “They are typically negative thoughts, about worries and fears. They are preoccupying and get in the way, making it hard to get to sleep, or interrupting what should otherwise be productive time during the day.”

Rose came to think of what she saw the girls doing as co-rumination. Unlike rumination, which typically has only negative effects on one’s mental health, co-rumination has both positive and negative aspects, “what we call ‘adjustment trade-offs,'” she says. “Disclosing and sharing information at more normative levels only has positive adjustment outcomes. It is related to having closer, higher-quality friendships, but also to greater depressive and anxiety symptoms. We often think of co-rumination as ‘too much of a good thing.'”

[See: 7 Types of Friends You Need to Break Up With.]

Girls Are More at Risk

Since she launched the concept and research into co-rumination, the idea has been considered in hundreds of studies and cited in the scientific literature thousands of times by researchers around the world, including the U.K., Germany, Sweden, Finland, New Zealand, China, South Korea and others.

One of Rose’s studies, for example, published in the July 2007 issue of the journal Developmental Psychology, found that girls are more likely than boys of the same age group to develop anxiety and depression as a result of extensive conversations with friends about their problems.

A six-month longitudinal study of 813 third-, fifth-, seventh- and ninth-grade girls and boys found that co-rumination increased the quality of friendship but also increased depressive and anxiety symptoms, which in turn, contributed to greater co-rumination. Rose thinks that girls may be more likely to take personal responsibility for failures than boys, for whom co-rumination predicted only greater positive friendship quality and not increased depression and anxiety. Girls may intend to give and seek positive support with their friends, but those conversations instead contributed to increased depression, she surmised.

Rumination, either alone or in pairs, is familiar to everyone. “Most people rehearse or review scenarios in their mind. Some of this is quite constructive, as when we think through what we have to do the next day, and consider how best to sequence and approach each of the upcoming tasks,” Potash says. “What we or others will notice when rumination is at play is a sense of being stuck. It is a bit like trying to get your car out of deep snow, where you push the gas pedal and the wheels just spin, but the car doesn’t go anywhere. When your mind is going over something again and again with no sense of resolving anything, and continuing or worsening anxiety and distress, then you know you are in a troubling ruminative state.”

This state of mind often goes along with a number of other symptoms of depression, like low mood, trouble sleeping, diminished energy and problems with concentration, he adds.

[See: Trouble Sleeping? Ask Yourself Why.]

How to Get ‘Un-Stuck’

Getting out of that mental snowbank is the challenge. If there is already underlying, diagnosed depression, typical treatments such as antidepressant medications and psychotherapy can help.

“Cognitive behavior therapy is one well-studied approach. It does things like helping people to review problems in their mind in a more effective way — like thinking concretely about a problematic situation, including what’s wrong and how it could be dealt with differently next time, rather than just focusing on their negative feelings about the situation,” Potash says. “Dialectic behavior therapy is another useful approach that emphasizes mindfulness, where you can observe your negative thoughts from a dispassionate point of view, without moving to making distressing judgments about yourself.”

It is also important to change how one interacts with others. “Everyone talks about problems and talking about problems in moderation is healthy. When you feel like you spend most of your time with someone talking about problems, or see this behavior in other people, this is probably co-rumination,” Rose says. “Breaking the excessive focus on the problem will be important. Doing something different with the relationship partner that will provide a distraction, like doing a physical activity or going to the movies, should help.”

Her research also cautions parents to keep an eye on children, especially girls, with seemingly supportive friendships. While it is true that socially isolated kids are at risk for depression, research by Rose and others shows that what seem to be supportive friendships may also be a risk factor for depression and anxiety, if those friendships include excessive, unhealthy co-rumination.

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‘Co-rumination’ and Its Relationship to Depression originally appeared on usnews.com