Developmental Programming: Priming Disease Susceptibility for Subsequent Generations.

Racial and/or ethnic minorities carry the highest burden of many adverse health outcomes intergenerationally We propose a paradigm in which developmental programming exacerbates the effects of racial patterning of adverse environmental conditions, thereby contributing to health disparity persistence. Evidence that developmental programming induces a heightened response to adverse exposures ("second hits") encountered later in life is considered. We evaluated the evidence for the second hit phenomenon reported in animal and human studies from three domains (air, stress, nutrition). Original research including a gestational exposure and a childhood or adulthood second hit exposure was reviewed. Evidence from animal studies suggest that prenatal exposure to air pollutants is associated with an exaggerated reaction to postnatal air pollution exposure, which results in worse health outcomes. It also indicates offspring exposed to prenatal maternal stress produce an exaggerated response to subsequent stressors, including anxiety and hyper-responsiveness of the hypothalamic-pituitary-adrenal axis. Similarly, prenatal and postnatal Western-style diets induce synergistic effects on weight gain, metabolic dysfunction, and atherosclerotic risk. Cross-domain second hits (e.g., gestational air pollution followed by childhood stressor) were also considered. Suboptimal gestational environments induce exaggerated offspring responses to subsequent environmental and social exposures. These developmental programming effects may result in enhanced sensitivity of ongoing, racially patterned, adverse exposures in race/ethnic minorities, thereby exacerbating health disparities from one generation to the next. Empirical assessment of the hypothesized role of priming processes in the propagation of health disparities is needed. Future social epidemiology research must explicitly consider synergistic relationships among social environmental conditions to which gestating females are exposed and offspring exposures when assessing causes for persistent health disparities.