SOUTH BEND - Gerald Haeffel's latest study created quite a splash when it was published in Clinical Psychological Science this spring, but the associate professor of psychology at the University of Notre Dame actually confirmed something many people had long suspected -- that the attitudes and perspectives of your peers can affect the way you think.

Haeffel, who studies depression, found thought patterns, including those that often predict who will develop depression, can spread from one college roommate to another.

This does not prove that depression itself is "contagious" (as was stated in many headlines in the weeks after the study was published), but it does illustrate the powerful effects that surroundings can have on one's psyche.

"The focus of research in my lab is what is called the cognitive theory of depression," Haeffel said. "Given the same negative life event, why is it that one person becomes

depressed and another person doesn't? Our lab and other labs believe that it's how you interpret those events."

Haeffel said that people tend to develop a clear style of dealing with negative events around adolescence. Some people might look at a bad grade on a test as a sign that they didn't study hard enough or need to seek out extra help from a teacher. Others might put the experience out of their mind by exercising or undertaking a new project. These people all tend to be resilient when faced with difficult situations.

But some students might see a failing grade as proof that they aren't smart enough to succeed or begin to worry that one test score will derail their futures. People with this style of thinking (or "cognitive vulnerability") are statistically much more likely to develop depression, even if they've never had symptoms before, according to Haeffel.

Haeffel said a conversation with Jennifer Hames, a student who became the second author on the study, led them to wonder if these thinking patterns were actually permanent.

"It seems like once you develop them you're stuck with it, sort of like a genetic risk factor," Haeffel explained. "But what happens when your life really changes? Could these (thinking styles) change?"

After some brainstorming, the two decided that college freshmen would be the perfect group to study.

"You have to live with new people. Your old friends are gone, your parents are gone," Haeffel said. "Whatever social environment you had that might have been influencing how you think about those things, it's all gone."

Haeffel decided to follow 103 pairs of randomly assigned freshmen roommates, asking them to fill out an initial survey and follow-up surveys three and six months later. He and Hames found their initial hunch was correct: students who were assigned roommates with high cognitive vulnerability saw their cognitive vulnerability rise over the course of six months.

But the news isn't all bad. The reverse is true, as well -- participants benefited from living with positive roommates, and saw their cognitive vulnerability decrease.

"That's the part that's been overlooked the most," Haeffel said. "It actually has treatment implications. We used to think if you had a negative style, there wasn't much we could do about it. But this showed that if you changed the social environment, if you have other people around who can model more adaptive ways of thinking, those will rub off."

Haeffel said this is good news for the field of cognitive therapy, which is well regarded by many psychologists but doesn't get the same amount of attention as antidepressant drugs.

"If there's a good thing about our paper getting some press, it's that you never see a commercial about thinking patterns on TV. You never see a commercial for cognitive therapy," Haeffel said. "If you get therapy that targets your thinking style, you're probably going to get better."

And while thinking patterns do affect our mental health -- and, we now know, the mental health of those around us -- Haeffel says there's no need to see a rainbow in every cloud.

"Sometimes things are really bad, and that's OK," Haeffel said. "Just don't make them overly bad. Even if something's horrible, it doesn't necessarily mean you're worthless, and it doesn't necessarily mean the rest of your world is going to fall apart."