Secondary prevention is when you see some of the beginning signs, you rush in and try to keep it from getting worse. The third area of prevention is tertiary and that really means doing something to reduce the handicap after it has been established. Those who live at poverty levels are the highest risk group. For example, the group with the highest rate of alcoholism, drug abuse, mental disorders, is the 5,000,000 migrant farm workers. They live in poverty, they move all the time, their children cannot get adequate schooling, their kids work in the fields with them, they never earn enough money to pay their bills from the company that supplies them with food, drink and cigarettes, so they are an exploited group.
Any exploited group is high risk.
People in the northern countries, Scandinavia, Finland, and Iceland have better health and lower rates of mental disorder. England is somewhere in the middle. 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.