According to the Chair of environmental epidemiology at Imperial College London, professor Paolo Vineis, after smoking, physical activity and diabetes, socioeconomic position (SEP) is the fourth most common factor that leads to a reduced life expectancy. So, what exactly is SEP and why does it have such a tremendous impact on health?

The SEP of an individual encompasses both their status or prestige and their occupation, which relates to power and chances in society. It has long been known that communities of individuals from low SEPs are more susceptible to drugs, alcohol and smoking – perhaps, as a coping mechanism.

SEP and substance abuse

The Centres for Disease Control and Prevention (CDC) considers individuals with a low-income to be at high risk of overdose. In fact, there have been a number of experiments conducted on animals to test the association between addiction risk and environment.

A study conducted by Michael Nader using male monkeys, showed that monkeys who were dominant within their social group self-administered less cocaine than more subordinate monkeys and solitary ones.

Evidence suggests that the reason for this connection is that brain circuitry in the insula, which is an important area for processing emotions, may have lowered dopamine-receptor availability, depending on social status. And this can turn into a vicious cycle, as many addicts may know – increased drug use can result in further isolation, which in turns makes them crave for more. Coping is not the only reason though, it is also true that these communities have poorer access to quality health care.

Does genetics play a role?

Vineis performed a study on the association between SEP and life expectancy, accounting for risk factors such as smoking and drinking. The results of this study, which was published earlier this year in The Lancet showed that the number of years of life lost between the category with the highest SEP and the category with the lowest, was 2.1. Vineis, however, noted that there were only three categories of SEP in their study. Had there been more, he said, the number of years could have gone up to eight. Vineis believes this is because SEP affects DNA methylation, or the modulation of the functioning of genes, which plays a role in ageing.

This is not a far-fetched theory. As a matter of fact, the Social Epigenomics Research Focused on Minority Health and Health Disparities initiative in the US has allocated money to ten research projects which aim to better understand the connection between genetic factors, SEP and health outcomes.

“Early life adversity, such as exposure to emotional or physical abuse or neglect, might alter DNA methylation levels creating an epigenetic signature, which in turn might influence risk of cardiovascular disease, cancer, stroke, and mental illness,” said the National Institutes of Health in America (NIH).

What about on an individual level?

Meena Kumari, professor for biological and social epidemiology, at the University of Essex, has studied the association between systemic inflammation in individuals and SEP. There are two reasons why individuals in low SEP environments face systemic inflammation.

According to the NIH, “higher levels of exposure to environmental hazards” is one reason. As Meena explains, some individuals could be breathing in pollutants because they live in a mouldy home, for example.

The second reason is the relationship between the inflammatory system and the stress system. Over time chronic stress causes systemic inflammation. The study, which was published in the Scientific Reports journal earlier this year, took blood samples of nearly 40,000 individuals and used the biomarkers C-reactive proteins and fibrinogen to measure inflammation.

Whilst there is evidence that C-reactive protein is raised in elderly disadvantaged people, Kumari wanted to learn if there is a correlation across all adults. She found that between ages 30 and 50, both biomarkers increased but they increased faster in individuals with a low SEP. Even adjusting for risk factors like smoking and drinking, Kumari’s team found that individuals with a low SEP suffer chronic stress and systemic inflammation far more than their higher SEP counterparts.

How can all of this information be used?

In Iceland, it is already being used as preventative medicine. Teenage substance abuse has dramatically reduced by creating more enriched environments through increased parental involvement and youth participation in team sports. Also on a community level, population health management will help to reduce health disparities among underserved patients.

Better understanding of the effect of variations in SEP will be able to help public health officials, lawmakers, and clinicians develop new strategies to address the negative variations. Genetically, “by identifying epigenetic modifications early before the onset of diseases, it may be possible to tailor interventions to prevent chronic conditions or diseases later in life,” the NIH notes.

Vineis believes doctors should be aware of a patient’s SEP whilst diagnosing and treating. MIMS

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