As a society becomes more and more unequal, status anxiety increases across all income deciles, not just the poor. People tend to worry more about whether or not they appear as successful or as a failure, causing considerable stress around work and social situations. Regardless of an individual’s level of income, how income is distributed within a society has been seen to greatly influence its levels of depression.
As the gap between the top and bottom earners widens, feelings of insecurity and shame increase among those on the lower end. This is known as the “psychosocial theory” of income inequality and health. These feelings are particularly dangerous in a society such as the U.S. where the majority of people, even the poor, tend to believe that everyone is able to achieve the “American Dream” — even as research suggests that social mobility in America is worse than many other countries across the world. One result of the disparity between aspirations like these versus reality is that when individuals attempt and fail to achieve socio-economic success, they often blame themselves, leading to feelings of shame, hopelessness, and demotivation.
As previously noted, income inequality may also decrease social cohesion, leading to poor protection of those most vulnerable, and consequently increase their social exclusion and isolation. To make note of its pervasiveness in the natural world, the link between a low social rank and psychological distress has also been observed in animal studies. Researchers at Wake Forest School of Medicine used brain scans to look at the neurobiological changes in 20 macaque monkeys when introduced into situations of social hierarchy. The monkeys began in individual cages and were then separated into groups of four so researchers could observe the hierarchies that developed, noting which monkeys were dominant and which were subordinate. They then taught the monkeys that they could administer cocaine to themselves by pushing a lever, and allowed them to take as much or as little as they liked.
What they found was that the monkeys that became dominant in the hierarchies exhibited higher levels of dopamine than they had before becoming dominant, whereas monkeys that became subordinate in their groups showed no changes in dopamine. When it came to cocaine distribution, the dominant monkeys consumed significantly less than the subordinate monkeys, while the subordinate monkeys appeared to medicate themselves against the impact of their low social status. These results serve to reinforce the theory that inequality is causally related to mental illness and its associated outcomes, and that this is a phenomenon that is not solely limited to humans.