The Smoking Gun

Alright, here's the abstract:
-Epidemiology and heart disease
-Heart disease -- more about what you do or where you do it?
-Fundamental causes
-Contextualizing risk factors
-"Stress is the new tobacco."
-A big bunch of links to several academic webpages and articles.

So I've discussed a bit about epidemiology and my interest in the social determinants of health (SDH). Traditionally, epidemiology focuses on individual behaviors as causal factors for non-infectious disease risk (non-infectious diseases such as diabetes, heart disease, cancer, etc. A case can be made that SDH plays a role in incidence of infectious diseases as well. I'll touch on that another time).

I'll use not only the most deadly non-infectious disease, but the number one killer in the U.S. as an example: heart disease.
Epidemiology focuses on population level risk factors for heart disease. As such, perhaps we should take a step back and contextualize individual behaviors within the broader picture of where and how people live. What factors have an effect on behaviors? Can there be earlier interventions for better preventive measures? What I'm talking about here is what puts people at "risk of risk," as Jo Phelan and Bruce Marmot called it.

What is the fundamental cause of heart disease? Bio-medically speaking, we can talk about artery blockages that reduce blood flow to the heart, starving tissues of oxygenated blood and eventually causing a cardiac event (heart attack or stroke). But what causes the blockages? Physicians consider many factors: Does the patient have a healthy diet? Is the patient obese? Does the patient take time to exercise daily? Does the patient smoke? What is the racial identity of the patient (this can make a difference, I'll explain further in a moment)? There are several measurements taken into account by physicians, and often times a regimen including better diet and exercise, smoking cessation, and medication are prescribed.

I'll contextualize these factors, and address each one individually. Studies have shown that those in poverty are less likely to have a healthy diet, a factor which is directly related to obesity. Those in poverty are less likely to exercise, and this often isn't a choice. In fact, there is evidence to support the idea that regardless of income level, living in a "poor area" has a negative impact on your health. Furthermore, we know that those living in poverty are far more likely to smoke, increasing risk of heart disease. Read more on the links between poverty and tobacco use here. Multiple studies have shown that there is a major link between poverty and race, and people who identify as African Americans and non-white Hispanic suffer the most. The links between race, poverty, and disease have been discussed and researched again and again and again. A simple perusing of the available research quickly demonstrates a clear link between socioeconomic status and heart disease. The ability to treat and recover from heart attacks is also directly related to socioeconomic status. The stresses involved in dealing with our complex medical and insurance system has cost lives and hope in the battle toward recovery, and that stress is increased for those of low socioeconomic status.

Then what about stress? There's a lot of talk out there about how stress is the "new tobacco." Stress responses were originally present in our bodies as a way to protect ourselves from danger. The old "fight or flight" response. The opposite of this is the perhaps less known "rest and digest." So the difference in our modern world is the lack of life-threatening saber tooth tiger attacks and the over-filled bag of deadlines and schedules. Fight or flight is supposed to be temporary, to subside once we've flown or fought. A sustained state of fight or flight cuts down our body's ability to rest and digest, to repair itself, to do the upkeep necessary to stay healthy. What that means is that sustained levels of stress cause cortisol buildup in the body, interfering with the rest and digest state, causing damage to our internal organs and processes. Modern day stress is a major contributor to heart disease. It's killing us.

So let me make my point in no uncertain terms: There is an undeniable link between health and socioeconomic status. Inequality is deepening, and the poor of our country are suffering and dying at increasing relative rates, while our medical technology and life-saving measures keep getting better. It is unethical and unacceptable. We see here that simple behaviors or biomedical measurements are important, but they aren't the smoking gun. To get a true understanding of health in our country, we must fully understand the effects of socioeconomic status.