There is a marvelous book called Unhealthy Societies written by Richard Wilkinson. He takes a look at different societies, and most important is the size of the gap between the rich and the poor. As a general rule, a society that has a narrower gap between the rich and the poor, has better health, significantly longer life expectancy, better mental health, fewer people in prison. There are a whole series of positive things tat go along with a narrower gap. In those countries with the widest gaps, you have the worst health and the shortest life expectancy.
Poverty is one of the major causes of mental and emotional problems.
Yes, the United States is way down on the list. Interestingly, the top two countries in terms of narrow disparity between rich and poor, the best two countries in that respect are Sweden and Japan. It is also interesting that in Japan very few people go to jail. Instead they are in rehabilitation of some kind. The police are seen as kind of counselors, and their prisons are almost a last resort.