The effects of nonshared environments on adolescent depression: Findings from a sample of monozygotic twins

Purpose: Behavioral genetic research has revealed that nonshared environments are associated with depression and depressive symptomatology. Research examining specific nonshared environments related to adolescent depression remains relatively limited. To address this gap in the published data, we analyzed a sample of monozygotic (MZ) twin pairs from the National Longitudinal Study of Adolescent Health (Add Health) to examine the effects of nonshared environmental variables on adolescent depression. Methods: We used the MZ-twin-difference-scores method on data from MZ twins (n = 289 twin pairs) drawn from the Add Health to examine the effect of specific nonshared environments on adolescent depression. Results: Findings from the MZ-difference-scores analyses revealed that between-twin differences in maternal disengagement were significantly related to differences in adolescent depression. Additional analyses revealed that the association between adolescent depression and maternal disengagement was largely a child-driven effect. Conclusion: Compared with previous research that has implicated maternal socialization in the development of depression among adolescents, the results of the current study revealed that differences in maternal socialization were a response and not a cause of adolescent depression.