Stress links poverty to inflammation and heart disease

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Poverty can take a toll on health. People with lower incomes have a higher risk of many diseases, including heart disease, diabetes, and cancer. Some of this risk is driven by reduced access to health care. Lifestyle factors also play a role. For example, people with lower incomes have higher rates of smoking. But after accounting for such factors, extra unexplained risk remains.

Researchers have proposed that the body’s stress response may link poverty with disease risk. Long-term stress can increase inflammation in the body. Chronic inflammation is thought to play a role in the development of many health conditions.

In a previous study, researchers led by Dr. Ahmed Tawakol from Harvard Medical School used PET imaging to scan the bodies and brains of almost 300 people without known heart disease. They measured brain activity in an area called the amygdala, which helps regulate the body’s stress response. They also looked for markers of inflammation in immune cells and arteries.

That study found that people with higher levels of stress had increased activity in the amygdala and more inflammation in their arteries. They also had a higher risk of having a major cardiovascular event such as a heart attack or stroke over the next several years.

In follow-up research, Tawakol and his colleagues looked at the contribution of income to this inflammatory pathway. They focused on 289 of the study participants who had their current address recorded. The researchers used data from the U.S. Census to gather average neighborhood income for each participant. They then added this information to their model. The study was funded in part by NIH’s National Heart, Lung, and Blood Institute (NHLBI). Results were published on July 2, 2019, in the Journal of the American College of Cardiology.

People who lived in lower-income neighborhoods had higher levels of stress-related activity in their amygdalas. The increased amygdala activity was associated with greater inflammatory cell production in bone marrow and more inflammation in arteries.

The participants living in the lowest-income neighborhoods had 4-fold greater risk of a major cardiac event over the next 5 years than those living in the highest-income neighborhoods.