CitationJeong, Yeongmi (2022). The Effects of Peers' Genetic Predisposition to Depression on Own Mental Health. 2022 Add Health Users Conference. Chapel Hill, NC.
AbstractThe goal of this research is to examine whether peers’ genetic predisposition for depression affects one’s own mental health in the short- and longrun. Depression is a common mental disorder in the US (NIMH, 2020) and there has been growing concern about adolescent depression. Adolescents with depression are about three times more likely to be depressed in adulthood compared to non-depressed adolescents (Johnson et
al., 2018). Therefore, understanding the factors that affect adolescent depression is key for preventing and treating depression. Since peers have particularly strong impacts on each other during adolescence (Brown and Larson, 2009), peers’ mental health may be an important determinant of own mental health. Using linear regression models, I examine how peers’ genetic predisposition for depression affects one’s own mental health
during adolescence and later in adulthood. I define same-gender grademates' as peers and exploit genetic variation in peers’ genetic propensity for depression within schools across grades. For the analysis, I use the Add Health core files and genetic file. Core files include detailed individual characteristics such as age, gender, and mental health questionnaires that allow me to construct the Center for Epidemiological Studies
Depression Scale (CES-D-10). The CES-D-10 score is used to construct a binary measure of own depression, which is my main outcome of interest. The files also include detailed school, family, and parental information, which are used as controls in the analysis. The genetic file includes the polygenic risk score for major depressive disorder (hereafter, MDD score), a composite measure of genetic markers that are correlated with MDD. A higher MDD score implies a higher genetic risk for depression. I construct same-gender grademates’ average MDD score, which is the main explanatory variable of interest. I find that an increase in same-gender grademates’ average MDD score is significantly associated with an increase in the probability of being depressed in adulthood for both males and females, with weaker effects on adolescent own depression. I plan to explore the mechanisms underlying the relationship, including substance use, labor market choices, and educational performance and attainment. Findings from this research contribute to the literature in several ways. First, this study adds to the literature on the impact of peers on own mental health by considering peers’ genetic predisposition to depression, avoiding many of the empirical challenges associated with identifying peer effects (i.e., the reflection problem). Second, the results have implications for whether interventions to curb adolescent depression should be individual- or group-based. Third, this work contributes to the growing literature on social-genetic effects in the context of mental health.