The UNC Carolina Population Center (CPC) recently received notice of a $38.2 million award to continue to lead the National Longitudinal Study of Adolescent to Adult Health (Add Health), now entering its sixth wave of data collection. This award from the National Institutes of Health is on top of the already impressive $114,165,158 in funding the Add Health team has collected since March 1994.
Professor Kathleen Mullan Harris directed the Add Health study from 2004 to 2021, and this year, professor Robert Hummer assumes leadership. The Add Health team includes sociologists, psychologists, epidemiologists, geneticists, physicians, and research methodologists. They collaborate on study design, data collection, and making study results available to researchers all over the world. Based at CPC, these researchers work closely with RTI International, the University of Vermont, and Exam One. Currently, the study has over 50,000 registered users of Add Health data, and a bibliography of over 8,000 journal articles, presentations, manuscripts, books, book chapters, and dissertations using the survey’s findings — all catalogued by the CPC.
This study is a nationally representative, longitudinal survey of over 20,000 individuals born between 1976 through 1982. The cohort was first interviewed as adolescents in grades 7-12 (ages 12-19) between 1994 and 1995. Since then, four waves of additional data have been collected at ages 13-20 (1996, Wave II), 18-26 (2001-2002, Wave III), 24-32 (2008, Wave IV), and 32 to 42 (2016-2018, Wave V). The survey design yields a sample representative of United States schools according to region, urbanicity, school size, school type, and ethnicity. The study includes oversamples of underrepresented racial and ethnic groups, as well as individuals differing by immigrant generation status and family structure, such as two-parent, single-parent, or stepparent familes.
Information on many topics has been collected, including educational experiences, social relationships, personality and psychological characteristics, stressors, employment, children and parenting, and cognitive function. In addition, contextual data are linked to other data such as school and neighborhood characteristics, high school transcripts, and pollutant information. The most recent Wave V study collected genetic information and measures that capture metabolic, immune, cardiovascular, and renal function as well as inflammation.
The objectives for Wave VI will focus on the cognitive, mental, and physical health of Add Health participants, with particular attention given to disparities in health outcomes across racial and ethnic, socioeconomic, and gender subgroups of the population. The new wave of data will inform current trends, including rising health risks in middle-age and participants’ exposure to COVID-19.
Add Health has begun to answer important questions about the links between adolescent experiences with adult health outcomes. For example, as outlined by RTI , data from the study has correlated middle and high school students who have problems with homework being at increased risk for issues with drinking and smoking. In addition, adolescents embedded within social networks of friends, family, and school have better cardiovascular and metabolic health 15 years later than adolescents without strong network connections. Analysis on the ways the environment affects genetic influence on health and health behaviors in adulthood is underway.
Other examples include a recent study from PhD student Audrey Renson and colleagues that showed biomarkers of inflammation, metabolism, and macromolecular damage are early signs of gut microbiome aging in young adults, likely beginning as early as age 30. Another study by sociologist Taylor Hargrove and team found that women reported more depressive symptoms than men, and underrepresented racial and ethnic groups reported more depressive symptoms than their white peers. Results also exposed a difference in depression symptoms by race and ethnicity within each gender group and at varying times in the life course. By highlighting these vulnerable populations and understanding the age trajectories for depressive symptoms, it is easier to determine when interventions would be best suited in the life course.
These are just a few examples of how social, economic, and biological factors during adolescence and young adulthood can affect health outcomes later in life. Answers on how best to intervene and when can only be derived by a longitudinal study like Add Health that tracks individuals over decades. And while Add Health has garnered international recognition and many awards, including the 2016 Golden Goose, it is just one impressive research program of the many within social and behavioral sciences at UNC. Our programs in these disciplines were recently ranked number-one in the U.S. I look forward to following the continued findings from Add Health, and the survey’s critical contributions to society, for years to come.