Your roommate's negative thinking can increase your risk of depression months later— a new study on college freshmen finds that cognitive vulnerability in one roommate can be "contagious" to the other.

Cognitive vulnerability is a major risk factor for depression. According to cognitive models of the mood condition, people who negatively interpret stressful life events as their own fault, or as the result of circumstances they are helpless to change, are more likely to become depressed.

Psychologists use clinical measures of cognitive vulnerability as a fairly reliable predictor of someone's risk of having a depressive episode in the future, even if they have no previous history of depression. The trait seems to stay stable throughout adulthood, and probably develops at least partially as a result of negative interpersonal interactions early in life.

Gerald Haeffel and Jennifer Hames of the University of Notre Dame decided to investigate whether cognitive vulnerability can change at certain points during a person's lifespan— especially after major transitions like moving to college.

"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," they wrote in their paper.

The study, published in the journal Clinical Psychological Science, show that cognitive vulnerability can indeed be contagious among college roommates in their freshman year.

The researchers collected self-report data from 103 college roommate pairs, all first-year students who had been randomly assigned to live together by the university housing agency.

Participants completed a baseline assessment survey one month after arriving on campus, which included questionnaires that assessed cognitive vulnerability and depression symptoms. They completed the same assessments three months and six months later, along with a questionnaire about stressful life events they experienced.

Freshmen whose roommates displayed high levels of cognitive vulnerability were more likely to report similarly negative ways of thinking at both the three-month and six-month time points. Their increased cognitive vulnerability also made them more likely to show symptoms of depression at six months than those who had no such increase.

The cognitive shift did not seem to be related to the occurrence of stressful events, or to roommates' actual depressive symptoms. The researchers believe it specifically comes from adopting the thinking patterns of a roommate with high cognitive vulnerability.

In the paper, Haeffel and Hames write that the contagiousness of thinking patterns might be leveraged to create resilience to depression in groups. If a patient seems prone to depression because of negative thinking patterns among people in their social environment, it could help to give those friends and family feedback about how their interactions might be affecting the patient's mental health. "Surrounding a person with others who exhibit an adaptive cognitive style should help to facilitate cognitive change in therapy."

The researchers conclude that cognitive vulnerability can increase or decrease over time, especially in changing social contexts. They hope their findings can lead to further research on whether the cognitive trait of depression risk can be contagious in other transitional points in adulthood, like moving to a new city or entering a nursing home.

Social media platforms like Facebook and Twitter can also be significant influences on a person's cognitive framework. Previous research has shown that social media networks can display contagious influences on mood and obesity. Haeffel and Hames rasie the possibility that seeing barrages of emotional comments and tweets following stressful events like natural disasters or deaths can shift the way people think about the world and influence their risk for depression.

Check out Psychology Today or NakedApartments for some tips about how to stay positive if you have a depressed roommate.