It has now been 21 years since University psychology professor Joseph Allen began studying the relationships of 184 13-year-olds. In a project supported by grants from the National Institute of Mental Health and the National Institute of Child Health and Human Development, Allen set off in 1998 to prove that peoples’ functionalities are not all pre-determined by genes. To do this, Allen and his team — consisting of a University assistant psychology professor and two graduate students — interviewed each middle schooler, their best friends and their parents, in addition to observing the interactions between them. Versions of this process were continued each year after that, until romantic partners were brought in when the participants were 16- and 17-years-old. Once the participants reached middle adulthood, health outcomes were measured to identify signs of premature aging. “Social relationships in adolescents turn out to have implications that extend well beyond adolescence,” Allen said. “They have implications for mental health and physical health, including markers you can see with physiological assessments.” To identify premature aging, level changes of inflammation from the bloodstream, cholesterol measures and body mass indexes were all used as markers. Currently, the group is dealing with an area called epigenetic aging, which studies the extent to which certain genes turn off over time due to stress. Using blood samples taken from study participants a few years back, Allen and the team are currently awaiting results to determine whether or not certain participants have encountered this, and whether or not their adolescent relationships may have caused it. “We’re looking at the extent to which social relationship problems predict epigenetic aging,” Allen said. A large aspect of this research relates adolescent relationships to romantic relationships later in life. According to Allen, even platonic peer relationships in adolescence are some of the best predictors of the quality of romantic relationships that adults have in their late twenties. Joseph Tan, University assistant professor of family medicine, is one of the co-authors of the research paper who looked into this area of study in particular. “When adolescents expect responsive behaviors in close relationships, when they feel a sense of security in their relationship or when they expect a sense of security in relationships with other people … their interactions with their romantic partners contain more supportive behaviors, they contain more constructive conflict discussions [later in life],” Tan said. College can be a time of significant relationship formation, as college students are away from their friends and family and are around many peers their own age. During this new period, young adults bring in adolescent experiences which create expectations of what close relationships should look like. Though these expectations are set at a young age, they can change overtime. When asked about outreach programs to encourage adolescent relationships, Tan hopes that young adults will get help in effectively self-reflect on their own relationships. “I would expect that kind of outreach would focus on helping adolescents or even college students understand what [a good relationship] looks like and what their expectations are and helping them consider if that is really what htey want them to be and if that works well for them,” he said. Allen’s lab is currently working on the The Connection Project, a program for teenagers designed to promote deep, meaningful relationships. The program provides an environment in which teens can feel comfortable sharing their “real-self” and learn to give and receive emotional support. University graduate student Meghan Costello worked alongside Tan and Allen to publish a research paper specifically covering the participants at ages 16 and 17. The research paper was published in the Journal of Research on Adolescence in May 2019 , focusing on “the intensity effect” of adolescent close friendships. The article can be found here. Adolescents were followed over a period of two years, and data was collected from age 16 to 17. At the age of 16, teens and their best friends participated in a series of tasks. The 16-year-old and their friend were presented with a hypothetical scenario and had to work out an agreement. They were also instructed to ask each other for advice on a topic of their choice. Researchers characterized the subject’s engagement, autonomy and connection with their best friend as “friendship intensity.” The research concluded that teens’ interactions with their peers has an effect on their mental health over time. “We've called this the ‘intensification effect’,” Costello said. “The ways that this development plays out depends on the teen’s own mental health symptoms when they are 16.” Costello and the team found that both positive and negative mental health can be reinforced over time with intense friendship dynamics. Intense social interactions in which the teen was engaged and connected with their friend seemed to be able to produce both positive and negative outcomes. The research defined “good mental health” as low symptoms of aggression and depression, while poor mental health was characterized by higher levels of aggression and depression relative to their peers. Teens who had good mental health and sustained these intense friendships had improved mental health the following year. By contrast, kids with poor mental health — high levels of aggression and depression — had worse mental health the following year. With an understanding of how teen mental health develops over time, efforts can be taken to provide support for teens at risk for developing poor mental health before symptoms become worse. “When best friends interact with one another regularly and with intensity, they appear to reinforce pre-existing qualities,” Costello said. The hope is that by providing intervention, teens will be encouraged to develop close supportive friendships and improve mental health over time. With this in mind, Costello advises teens to pursue relationships that are supportive, in which both parties communicate openly and receive positive influence. Historically, the influence of teenage friendships has focused on the negative influences of peers. With new research, the hope is to shift the dialogue towards the more positive influence that adolescent relationships have for teenage development. In a rigorous academic environment, it can be tempting to focus on academic achievement over interpersonal relationships. The takeaway for college students is that developing close friendships and relationships is important for both mental and physical health. In college, like in high school, students should prioritize relationships with others and work to build bridges with their peers. Allen has now received an additional grant of $3.1 million from the NICHD to continue his research for an additional 10 years, further telling how relationships in adolescence affect adulthood. At its conclusion, the 184 participants will be in their mid-forties.