“Epigenetics is an emerging frontier of science that involves the study of changes in the regulation of gene activity and expression that are not dependent on gene sequence . . . the origins of health and susceptibility to disease are, in part, the result of epigenetic regulation of the genetic blueprint.”
– NIH Roadmap Epigenomics Project
Lana Jones (not her real name) was a very pleasant yet timid young woman I met when I was a senior medical student on a public health elective. She could have passed for your average twenty-something, except she was in the medical exam room at a homeless clinic in downtown Phoenix. She had arrived by shuttle bus from a nearby women’s shelter for domestic violence survivors. Lana was on the run from an abusive husband and had barely escaped with her life, but not with her ID, money, or basic necessities. She was in the clinic with uncontrollable panic attacks, headaches, stomach upset, insomnia, and likely PTSD. For the first time, I became painfully aware of just how quickly a person who didn’t fit any of my stereotypes could become homeless.
Often, when an individual is homeless, it is easy to conclude that self-destructive or reckless behaviors are to blame, such as in the cases of drug use or financial irresponsibility. But the real answer is multifactorial and never one-size-fits-all. Genetic predispositions are important contributors, such as those related to severe mental illnesses or addictions. Both risk factors and confounding factors in people experiencing homelessness, they pose significant hazards for premature mortality. Beyond genetics, epigenetics and social determinants play a weighty but poorly addressed role in the onset, severity, and outcomes of homelessness and linked conditions.
The World Health Organization defines social determinants of health as “the conditions in which people are born, grow, live, work and age, including the health system. These circumstances are shaped by the distribution of money, power and resources at global, national and local levels, which are themselves influenced by policy choices.” Adding complexity, there are also “upstream” factors of the social determinants that are relevant to the risks of homelessness. Examples include a history of abuse/trauma (as in Lana’s case), recent incarceration, veteran status, and family/social rejection of individuals with transgender status. Stressors, trauma, and related co-morbidities do not change a person’s genome, but they do have profound effects on how genes are expressed and regulated. These epigenetic changes can result in higher incidence of anxiety, depression, suicidality and substance abuse, alongside other co-morbidities of cardiovascular, metabolic and infectious diseases.
Lana’s past medical history, including family history, provided no evidence for significant genetic risks. However, her social determinants increased her risk of homelessness. Epigenetic changes increased her risk of life-altering and life-threatening conditions like depression/suicidality, traumatic brain injury, and premature heart diseases. In addressing Lana’s concerns, I realized that providing meaningful care would involve a lot more than just treating her symptoms that day.
Looking at individual patients as members of a population, we can see that social determinants plus geocoded data, such as zip code, may factor more loudly in potential for wellness than genetic code. Population trends in how genes are expressed in response to environmental and biopsychosocial factors could serve as a roadmap to how we can best design our preventive, public health, and treatment measures. Perhaps, in seeing “people experiencing homelessness” as patients who have fallen through the cracks of the healthcare system, we can find the will to build a better system, a system that takes into account all of the data regarding social determinants of health. We can work with policymakers to promote funding for universally accessible, integrated physical and mental healthcare, institute comprehensive services for people with mental health disabilities, create widespread addiction prevention and treatment, and launch effective root-cause-related measures against domestic violence and other sources of trauma. If we invest in a system that addresses social and behavioral determinants of health, then we will improve population health, social justice, and equality and lower costs compared to our current reality. In doing so, we will also more effectively care for those in our society who are most vulnerable to risks from the epigenetics of homelessness.
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Dr. Hartmark-Hill is a Mayo Clinic-trained family medicine physician who works as full-time faculty at The University of Arizona College of Medicine – Phoenix and sees patients at the Cholla Clinic (an FQHC underserved medicine clinic). She also serves as the medical director of Student Health Outreach for Wellness (SHOW), an interprofessional student-run free clinic. She completed her MD (and a year-long faculty development fellowship) through The University of Arizona College of Medicine. Her hobbies include watching stand-up comedy, reading (especially travelogues), hiking and camping in Arizona, urban farming (raised bed gardens and five chickens), and spending time with her wonderful husband, four sweet rescue dogs, and two plotting cats.