Introduction: Prior twin studies suggest that various types of social support (SS) are genetically influenced (h2ss up to 75% depending on the measure)1. One possible explanation for the observed heritability of SS is that the observed additive genetic contributions reflect effects on associated psycholopathology(ies) that might not have been measured/modeled (i.e., gene-environment correlation effects; e.g., personality traits). Given that it is still relatively unknown how SS affects depression and stress-related behaviors in African Americans, the present study examined the co-heritability of stress, depression, and perceived quantity and quality of emotional and instrumental support.
Methods: Data were collected from adult African American twins (MZ pairs=102 and DZ pairs=179 from 396 families; 41% male) who reported on SS provided by their friends and/or family over the preceding year. Participants described the quantity and quality of support in two distinct areas: (1) emotional support (i.e., activities such as being comforted when upset), and (2) instrumental support (i.e., receiving assistance in the form of advice, transportation, or money when needed). Additionally, an abbreviated 11-item Center for Epidemiological Studies-Depression (CES-D) scale was used to evaluate their depression over the past week, and the Perceived Stress Scale (PSS) was completed to measure participants’ appraisal of stress over the past month. Univariate twin models were run to determine the role of additive genetic (A), non-additive genetic (D), or common/shared environment (C) effects, and non-shared environmental effects (E). Bivariate twin analyses examined the relationship between instrumental SS and depression, as well as instrumental SS and stress. All models were run using Mplus (version 8) and controlled for variation in age and gender.
Results: The estimated broad-sense heritability differed across depression, perceived stress, and both indices of social support. AE models best described depression, perceived stress, and quantity/quality of instrumental support. The best fitting models were: 1) AE effects on perceived stress (a2=0.22) and depression (a2=0.47), 2) CE effects on the quality and quantity of emotional support (c2=0.18 and c2=0.19, respectively), and 3) AE effects on the quality and quantity of instrumental support (a2=0.23 and a2=0.17, respectively). Bivariate AE models testing the genetic and non-shared environmental covariance between depression and both types of instrumental social support indicated moderate genetic overlap (rADEPRESSION-QUALITY= -0.64, Δχ2rA-DEPRESSION-QUALITY = 1.852, Δdf =1, p=0.17, ΔBIC = -0.61; rADEPRESSION-QUANTITY= 0.79, Δχ2rA-DEPRESSION-QUANTITY = 0.73, Δdf =1, p=0.39, ΔBIC = -1.74). Similarly, additive genetic effects on perceived stress were common with instrumental quality (rASTRESS-QUANTITY= -0.74, Δχ2rA-STRESS-QUALITY= 1.79, Δdf =1, p=0.18, ΔBIC = -0.68) and with instrumental quantity (rASTRESS-QUANTITY= 0.65, Δχ2rA-STRESS-QUANTITY = 0.134, Δdf =1, p=0.71, ΔBIC = -2.33).
Discussion: The current study provides novel insight into the relationship between stress, depression, and social support in African Americans. Moreover, the possibility of a gene-environmental correlation (evocative/active) suggests cautionary use of social support indices as moderator variables of risk for depression and stress.
References: 1. Kendler, K. S. (1997). Social support: a genetic-epidemiologic analysis. The American journal of psychiatry, 154(10), 1398-1404.
Health (e.g., BMI, Exercise) , Positive Psychology/Wellbeing , Psychopathology (e.g., Internalizing, Externalizing, Psychosis) , Substance use: Alcohol, Nicotine, Drugs
