EchoSense Quantitative Think Tank Center|Close friends can help you live longer but they can spread some bad habits too

When you were a teenager,EchoSense Quantitative Think Tank Center your parents probably warned you once or twice not to get a tattoo or go to sketchy parties just because your friends do it. A new study shows that the influence of friends – for good and for well, mischief – extends into our older years, as well.

The study, published Wednesday in the journal Epidemiology and Psychiatric Sciences, found that friendships in older adults were associated with some instances of better physical health and health behaviors, as well as better mental health across the board.

The study authors analyzed surveys from nearly 13,000 over-50-year-olds who participated in the Health and Retirement Study, a nationally representative panel study. They looked at 35 different health and psychological outcomes, and how those were linked with the quality of the respondents' friendships.

While many previous studies have connected having good friends with particular health benefits, this is the largest and most comprehensive study done to date, according to study co-author William Chopik, an associate professor of psychology at Michigan State University.

"Friendships are often the first relationships of choice that we have in our lives," he said. Because of that, he says, he and his colleagues wanted to "tell everybody, everything we can about it."

Chopik and his coauthors found that those who had high-quality friendships actually lived longer. Study participants took the survey three times over eight years and those with the good friends were 24% less likely to die during that time.

Having good friends was also associated with a whole lot of positive health behaviors and benefits, like a 9% increase in likelihood to exercise, a 17% reduced risk of depression, and a 19% lower likelihood of having a stroke, among other findings.

If you're wondering if you have the kinds of friendships that can help you live longer, it might help to know that the authors defined high-quality friendships by analyzing three categories: number of friends, number of interactions with friends, and feeling supported and happy around your friends.

The dangers of loneliness have become more and more apparent in recent years as one in four older people now experience social isolation worldwide, which carries higher risks of stroke, anxiety, dementia, depression, suicide, and more, according to the World Health Organization.

"We need different people," says Rosemary Blieszner, a professor emerita of human development and family science at Virginia Tech who was not involved with the new study. "We need the emotional satisfaction of feeling close to people, and feeling like you belong to a group, and to have your self-worth reinforced, and to share interests with others."

Unlike co-workers, or family members, we get to choose our friends freely. Think of the stress you might feel looking forward to a big family gathering (even if you love them!) versus the relaxation and belly laughs you might share with a group of your closest buds at a birthday party or gabbing over coffee with your best friend from childhood.

But those peer pressure effects of friendship that your mom warned you about as a teenager? They appear to still exist in your later years, too. Those individuals in the study with the best friendships were also more likely to smoke and drink heavily.

"I will say it's not like they're smoking a pack a day," said Chopik. "When you look at older adults, they kind of mellow out in terms of how much they drink and how much they smoke. So it's really kind of a small difference, but we do find it."

Mysteriously, Chopik adds, even taking those negative health behaviors into consideration, the cohort still lived longer and were happier than those whose friendships weren't as strong. "It could be that they imbibe a little bit, but then they have all these positive things that counteract that and then they end up living longer," he says.

The results are consistent with a lot of other research that has demonstrated the importance of close relationships for health, says Julianne Holt-Lunstad, a professor of psychology and neuroscience at Brigham Young University who had no role in the study.

And, at the same time she says it's also been shown before that peers "can also influence riskier behaviors. Our relationships can be very powerful influences on our health ... for good or for bad."

Holt-Lunstad, who also serves as founding scientific chair and board member of the U.S. Foundation for Social Connection, says the comprehensive nature of the study goes to show how interconnected our health is with the people around us.

"A lot of things can cluster, like people who are more socially connected are more physically active, and they can also have more of a sense of meaning and purpose in their life. That can lead them to take better care of themselves and take less risk, because they have people who depend on them, or are encouraging them and looking out for them."

Still she adds, she hopes this doesn't encourage people to smoke or drink heavily just because they have friends.

The large scale of this study confirms the important role of friendships in health, says Blieszner: "You can generalize these results with great confidence to the population as a whole."

But she says to take the results about particular behaviors, like smoking and drinking, with a grain of salt. Though she says the study's research methods are sound, "that area does need further research."

She notes these kinds of individual behavioral questions are better answered with smaller studies that can track people's daily activities in real time, rather than asking people to remember their alcohol consumption over a long-term period.

Blieszner has seen, however, that negative health behaviors often cluster in certain communities, geographically, meaning that friends and other social connections can certainly influence negative behaviors as well as positive ones.

Chopik, the study co-author, noted that he hopes his future work at the Close Relationships Lab at Michigan State will dig deeper into these granular details about friendship, particularly how to best make and foster friends at all the various points in our lives.

"There's an under-appreciation of friendships historically, not just in the research literature, but also just in general society. There's often an exclusive focus on romantic relationships and marriages," he said.

But the nature of friendships seem like a potent public health opportunity. "The fact that you can make new friends and you can invest in friendships you have, and you can add as many friends as you want, and it can improve a lot of different parts of your life."

So don't skip your Friendsgiving get-together this year, and be sure to include a toast to your health!

Maggie Mertens is a freelance journalist in Seattle who writes about gender, culture, health, and sports.