Harsh Parenting and Serotonin Transporter and BDNF Val66Met Polymorphisms as Predictors of Adolescent Depressive Symptoms

Abstract

Depressive symptoms are prevalent and rise during adolescence. The present study is a prospective investigation of environmental and genetic factors that contribute to the growth in depressive symptoms and the frequency of heightened symptoms during adolescence. Participants included 206 mother–father–adolescent triads (M age at Time 1 = 13.06 years, SD = .51, 52% female). Harsh parenting was observationally assessed during a family conflict paradigm. DNA was extracted from saliva samples and genotyped for the 5-HTTLPR and BDNF Val66Met polymorphisms. Adolescents provide self-reports of depressive symptoms annually across early adolescence. The results reveal Gene × Environment interactions as predictors of adolescent depressive symptom trajectories in the context of harsh parenting as an environmental risk factor. A BDNF Val66Met × Harsh Parenting interaction predicted the rise in depressive symptoms across a 3-year period, whereas a 5-HTTLPR × Harsh Parenting interaction predicted greater frequency in elevated depressive symptoms. The findings highlight the importance of unique genetic and environmental influences in the development and course of heightened depressive symptoms during adolescence.

ACKNOWLEDGMENTS

We are grateful to the families who participated in this project. Our gratitude is also expressed to the staff and students who assisted on various stages of the project, in particular to Jana Lam for her assistance with the observational coding.

FUNDING

This research was supported by grant R01 MH57318 from the National Institute of Mental Health awarded to Patrick Davies and E. Mark Cummings and by the Spunk Fund, Inc., awarded to Dante Cicchetti. Support was provided to Kalsea J. Koss by National Institute of Mental Health training grants (T32 MH015755 and T32 MH018921) during the preparation of this article.

Notes

¹ Prior to fitting the full model with covariates, genetic variants, and interaction variables, harsh parenting was examined as the sole predictor in the LCS model. There was no main effect of harsh parenting on the intercept (β = .09, p = .28) or slope (β = .01, p = .97) of depressive symptoms.

² ZIP analyses were conducted examining harsh parenting as the sole predictor, and harsh parenting was not associated with being in the zero group (Β = –.86, SE = .87, p = .32) or the frequency of elevated depressive symptoms (Β = –.04, SE = .04, p = .29).

Additional information

Funding

This research was supported by grant R01 MH57318 from the National Institute of Mental Health awarded to Patrick Davies and E. Mark Cummings and by the Spunk Fund, Inc., awarded to Dante Cicchetti. Support was provided to Kalsea J. Koss by National Institute of Mental Health training grants (T32 MH015755 and T32 MH018921) during the preparation of this article.