"'Ultimately, we see our story as about the collapse of the white, high-school-educated working class after its heyday in the early 1970s, and the pathologies that accompany that decline,' they conclude."

'Sea of despair': Death rates stay up for US working-class whites

Offering what they call a tentative but "plausible" explanation, they write that less-educated white Americans who struggle in the job market in early adulthood are likely to experience a "cumulative disadvantage" over time, with health and personal problems that often lead to drug overdoses, alcohol-related liver disease and suicide.

"Ultimately, we see our story as about the collapse of the white, high-school-educated working class after its heyday in the early 1970s, and the pathologies that accompany that decline," they conclude.