In 2015, a blockbuster study came to a surprising conclusion: Middle-aged white Americans are dying younger for the first time in decades, despite positive life expectancy trends in other wealthy countries and other segments of the US population.The research, by Princeton University’s Anne Case and Angus Deaton, highlighted the links between economic struggles, suicides, and alcohol and drug overdoses.Since then, Case and Deaton have been working to more fully explain their findings.They’ve now come to a compelling conclusion: It’s complicated. There’s no single reason for this disturbing increase in the mortality rate, but a toxic cocktail of factors.In a...