“Most men lead lives of quiet desperation,” Henry David Thoreau wrote in “Walden.” Now that despair may be killing more of them too, especially if they’re white, middle age and without a college degree.

An analysis published Thursday by the Brookings Institution finds though midlife mortality rates are falling among all education classes in most of the rich world, middle-age, non-Hispanic whites in the U.S. with a high school diploma or less are dying faster, many due to “deaths of despair” — deaths involving drugs, alcohol and suicide. A slowdown in progress against heart disease and cancer also has contributed to the trend.

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In 2015, the rate of whites with no more than a high school education was 30 percent higher than blacks. The reverse was true in 1999.

Princeton Professors Anne Case and Angus Deaton found for people 45-54 years of age, sex made no difference when it came to deaths of despair, nor did geographic location, blaming the increase instead on the deterioration of economic and social well-being.

“The story is rooted in the labor market, but involves many aspects of life, including health in childhood, marriage, child rearing and religion,” the authors wrote.

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The trend began in the 1970s as high-paying union manufacturing jobs began disappearing to globalization and automation, hitting working-class whites particularly hard.

“This doesn’t seem to be just about income. This is about accumulating despair for these people,” Ms Case told the Financial Times. “The white working class may see itself now as the bottom rung of the ladder [in America].”

The analysis stemmed from a 2015 study Case and Deaton published in the Proceedings of the National Academy of Sciences that noted the trend but did not explore the reasons behind it.

“As the labor market turns against them, and the kinds of jobs they find get worse and worse for people without a college degree, that affects them in other ways too,” Deaton told the Atlantic.

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More white, middle-age Americans are dying deaths of despair as economic opportunities dwindle and the social fabric frays. Creative Commons

Deaton said members of the age group see themselves doing worse than their parents, shattering expectations and leading them to turn to risky behaviors like overeating, alcohol abuse or drug use.

“We are trying to say that low income and low job opportunities, after a long period of time, tears at the social fabric,” Deaton said. “It’s the social fabric that keeps you from killing yourself.”

Government statistics indicate more Americans die of drug overdoses (47,000 in 2015) than car accidents (35,000).

Research by Shannon Monnat, an assistant professor at Pennsylvania State University, noted President Donald Trump did better than 2012 Republican presidential candidate Mitt Romney in counties with higher drug, alcohol and suicide death rates.