There has been an increasing disparity between the higher- and lower-income groups since the 1970s, with rapid growth for income earners at the top and middle- to low-income earners growing at a slower rate.

The disparity, however, is not always just economic.

The trend poses obvious issues, including rates of poverty and wealth concentration, but what does it mean for the growing population's stress levels and overall health?

Those among the higher-income Americans report having lower stress levels and being in better health compared to their lower-income counterparts, according to the Brookings Institution's economic policy initiative The Hamilton Project. This finding, based on self-reported health as well as laboratory-based measures, such as blood pressure and cholesterol levels, is directly associated with long-term stress on the body.

Self-reported Health Of Higher-Income vs Lower-Income Earners

In the study, individuals were grouped by their family income history: whether they were within the top, middle or low income bracket in the years covered by the survey. The data revealed that those with high family incomes reported being in very good health, and that those among the top third of the income bracket were twice as likely to report being in excellent health as compared to those in the lower income bracket.

However, it should be noted that reports of being in good or excellent health declined over time across all income groups, but the decline was insignificant among top income earners.

Obesity

The increase in the likelihood of obesity among all demographic groups is being widely documented, with more than one third of U.S. adults now considered obese. In the late 1970s, the relationship between income and obesity was particularly strong compared to more recent years. But what is surprising is that, while higher income individuals are less likely to be obese, they are still 50 percent more likely to be obese than low income earners in the 1970s.

Stress Load

Taking a look at the basic indicators of general health in relation to stress — cholesterol levels, blood pressure and kidney and liver function to name a few — it was concluded that those with higher income experience lower stress loads regardless of time period, while those with lower income experience heavier stress loads that could lead to various health problems.

Supportive of previous studies regarding stress and its contributing factors, the paper highlighted data collected from 1976 to 1980 and from 2009 to 2014, and took a closer look at the different income groups' self-reported health, obesity and stress levels.