Mirror neurons contribute to successful social connections

Q: I am a junior in college. I enjoy being around people, so I live in the dorms. Last year, my roommate was depressed, and I also got to feeling down. This year, the girl I live with is cheerful, and I’m having a much better time. Can you “catch” moods from someone you live with?

A: Your experiences with two very different roommates have led you to a theory known as emotional contagion. Scholars cite a paper written in 1993 by a trio of psychologists as the genesis of that phrase. However, the idea that the emotional state of another person can have a direct effect on our own feelings has been around for centuries. You’ll find examples in academic works, throughout literature and in everyday language. Someone who transmits bad feelings is a “killjoy.” Their opposite is “ray of sunshine.” Which would you rather spend time with?

Theories about the realm of emotions can be difficult to prove. After all, how do you quantify feelings? In a recent study about emotional contagion, a group of researchers from universities in the United States, Canada and Germany focused on a metric that is easy to measure: levels of the stress hormone cortisol. Their findings were published last fall in the journal Psychoneuroendocrinology.

Using data collected from 321 older couples — the participants ranged in age from 56 to 87 — the researchers found that when one of the partners was in a visibly good mood, the other partner experienced a measurable decrease in their level of the stress hormone cortisol. That is, those feelings of happiness and contentment were contagious. Another study examined data collected from 5,000 individuals from multiple communities. The researchers observed that when one person expressed happiness, the feeling often spread three degrees across an entire social network, affecting not only friends of the happy person, but also friends of friends.

Not surprisingly, a body of research suggests that the darker side of the emotional spectrum can also have a ripple effect. In one study, spouses whose partners were prescribed antidepressants had a 62% higher chance of using antidepressants themselves within the following year. In another study, college students who had been paired with a depressed roommate found themselves battling the same types of low moods after just a few weeks.

So what causes emotional contagion? One theory focuses on fascinating structures in the brain known as mirror neurons. These are nerve cells that fire when someone performs a physical action. What makes them unique is that they also fire when the person sees the same action performed by someone else.

As these neurons mirror the physical cues associated with emotions such as happiness, sorrow, anger, fear, anxiety or pleasure, they can provide us with a window into what other people are feeling. This understanding can facilitate the path to successful social interactions and connections.

Mirror neurons, along with the social contagion they make possible, are believed to also be crucial to the development of empathy, and to our ongoing emotional education.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.

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