The Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure Study (InterGEN): Design and Methods for Recruitment and Psychological Measures

Background Although studies show that genomics and environmental stressors affect blood pressure, few studies have examined their combined effects, especially in African Americans. Objective We present the recruitment methods and psychological measures of the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure (InterGEN) study, which seeks to investigate the individual and combined effects of genetic (G) and environmental (E) (psychological) stressors on blood pressure in African American mother-child dyads. Genetic methods are presented elsewhere, but here we present the recruitment methods, psychological measures, and analysis plan for these environmental stressors. Methods This longitudinal study will enroll 250 mother-child dyads (N = 500). Study participation is restricted to women who (a) are ≤21 years of age, (b) self-identify as African American or Black, (c) speak English, (d) do not have an identified mental illness or cognitive impairment, and (e) have a biological child between 3 and 5 years old. The primary environmental stressors assessed are parenting stress, perceived racism and discrimination, and maternal mental health. Covariates include age, cigarette smoking (for mothers), and gender (for children). The study outcome variables are systolic and diastolic blood pressure. Analysis The main analytic outcome is genetic-by-environment interaction analyses (G × E); however, main effects (G) and (E) will be individually assessed first. Genetic (G) and interaction analyses (G × E) are described in a companion paper and will include laboratory procedures. Statistical modeling of environmental stressors on blood pressure will be done using descriptive statistics and generalized estimating equation models. Implications The methodology presented here includes the study rationale, community engagement and recruitment protocol, psychological variable measurement, and analysis plan for assessing the association of environmental stressors and blood pressure. This study may provide the foundation for other studies and development of interventions to reduce the risk for hypertension and to propose targeted health promotion programs for this high-risk population.