Biological pathways for historical trauma to affect health: A conceptual model focusing on epigenetic modifications.

Despite their unique histories, environments, and lifestyles, historically subjugated populations consistently show poorer health outcomes compared to the general population. The theory of historical trauma, which argues that a collective trauma experienced by one generation can negatively impact the wellbeing of future generations, is a potential framework to understand the adverse health outcomes seen among populations with histories of subjugation. However, the biological pathways through which historical trauma actually impacts health have been unclear. In this paper, we present a cumulative, two pathway model that describes how historical trauma can impact health in contemporary generations. The first pathway suggests that personal exposure to trauma or stressors, which are more common among populations that have experienced historical trauma, can induce epigenetic modifications that can contribute to the development of poor health. The second pathway posits that poor health can occur through intergenerational epigenetic modifications in response to parental and grandparental trauma or stressor exposures. Taken together, these pathways can provide insight into the higher rates of adverse health outcomes among individuals from populations that have historically endured collective trauma. Importantly, the potential reversible nature of epigenetic modifications suggests that these trauma-induced epigenetic effects are not necessarily permanent and that improvements in environmental conditions could reduce the high prevalence of poor health among historically disadvantaged communities.