New study by two Princeton University economists has found that less educated middle-age Americans are increasingly dying younger compared to other middle-aged US adults. The researchers believe the trend was driven by dwindling economic opportunities.

The study was released on Thursday where Anne Case and Nobel Prize-winner Angus Deaton argued that the loss of steady middle-income jobs for those with high school degrees had triggered broad problems for the group. Compared to their college-educated counterparts, the group is more likely to be unemployed, unmarried, or afflicted with poor health.

Deaton said that this is the story of the collapse of the white working class. They helped fuel the rise of President Trump, who won support among whites with only a high school degree.

The new study is a follow up on previous research that Case and Deaton released in 2015, which first documented the sharp increase in mortality among middle-aged whites according to Boston Globe.

Part of their previous work, the researchers found that white men and women between the age of 45 to 54 have had an increase in deaths of despair since 1999. It included suicides, drug overdoses, and alcohol-related deaths.

In the new study, researchers draw a clearer relationship between rising death rates and changes in the job market since the 1970s. They found that men without college degrees are less likely to receive rising incomes. Men are consistently moving to lower and lower skilled jobs.

Researchers said it is not clear why these trends affect whites more than African-Americans or Hispanics, whose death rates happen to be improving. African-Americans have become more resilient to economic challenges given their long-standing disadvantages in the job market.

In 1999, high school-educated whites aged 50 to 54 had a 30 percent lower death rate from African-Americans. But by 2015, it went 30 percent higher. The researchers found that the rates for whites who are college graduates are also declining.

The spike in mortality rates started in the Southwest. Now it has spread across the country, affecting men and women from both cities and rural areas according to CBS News.