Depression is a major health concern worldwide. But the good news, according to researchers at the University of Warwick, is that a healthy mood amongst friends protects, and aids recovery, from depression. Teenagers were the focus group of the study.

Researchers studied the way that teenagers in a group of US high schools influenced each others’ mood. The academics sought to establish whether depression spreads from friend to friend.

Professor Frances Griffiths, head of social science and systems in health at Warwick Medical School said, “Our results offer implications for improving adolescent mood. In particular, they suggest the hypothesis that encouraging friendship networks between adolescents could reduceboth the incidence, and prevalence, of depression among teenagers.”

Using data from The National Longitudinal Study of Adolescent to Adult Health, they looked at more than 2,000 adolescents in a network of US high school students. They examined how their mood influenced each other, by tracking the spread of moods, using methods similar to those used to track the spread of infectious diseases.

The academics found that while having mentally healthy friends has a positive effect, having friends who suffer from depression doesn’t affect one’s own mental health. Friendships can help teenagers recover from depression or even avoid becoming depressed in the first place.

The team also found that while depression does not ‘spread’, having enough friends with a healthy mood increases the probability of recovering from depression over a six to 12 month period. So happiness is infectious but depression is not.

The research also suggests that adolescents who have five or more mentally healthy friends are 50 percent less likely to become depressed, compared with adolescents with no healthy friends. And teenagers who have 10 healthy friends have double the probability of recovering from depressive symptoms compared to adolescents with just three healthy friends.

Dr Thomas House, senior lecturer in applied mathematics from the University of Manchester said: “More work needs to be done, but it may be that we could significantly reduce the burden of depression through cheap, low-risk social interventions.”

The study offers hope. Depression, while widespread, needn’t become a juggernaut we can’t escape. It would be wonderful if, instead of reaching for a bottle of pills, we could reach out for a friend and discover how contagious happiness is!