Depression can be contagious, study claims

The idea that your mood is affected by those you spend time with is probably not news to you.

But what if we told you that something as serious as depression -- a chemical imbalance in one's brain that can immobilize some -- can be triggered by being around others who exhibit depressive behaviours.

A recent study by psychological scientists Gerald Haeffel and Jennifer Hames from the University of Notre Dame suggests that university students who live together can pass on their depression, though a mental process known as "cognitive vulnerability."

“Our study demonstrates that cognitive vulnerability has the potential to wax and wane over time depending on the social context,” the researchers write in their paper.

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Cognitive vulnerability -- a term used to describe a particular world view where people assume stressful life events are out of their control and occur because of their own deficiency -- is a significant risk factor for depression, the researchers say. Experiencing cognitive vulnerability makes individuals more likely to experience a depressive episode in the future, even if they have never had a depressive episode before.

The researchers hypothesized that cognitive vulnerability might be “contagious” during major life transitions, when our social environments are in flux.

To test their idea, they followed 103 randomly assigned roommate pairs, all of whom were in their first year of university.

"Freshmen are an ideal sample for testing the hypotheses because they are experiencing a major life transition that involves a significant change to their social environment, are at the peak age for developing depression and can be randomly assigned to a roommate," the researchers write.

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The participants completed an online questionnaire that measured cognitive vulnerability and depressive symptoms at the one-, three- and six-month mark. They also recorded any stressful life events at the three- and six-month mark.

The results reveal that those who had a roommate with high levels of cognitive vulnerability were likely to “catch” their roommate’s cognitive style and also develop higher levels of cognitive vulnerability. The effects were evident at both the three-month and six-month mark.

“Our findings suggest that it may be possible to use an individual’s social environment as part of the intervention process [to treat depression],” the researchers write.