After rising for decades, life expectancy in the U.S. decreased for three straight years, driven by higher rates of death among middle-aged Americans, a new study suggests.

Midlife all-cause mortality rates were increasing between 2010 and 2017, driven by higher numbers of deaths due to drug overdoses, alcohol abuse, suicides and organ system diseases, such as hypertension and diabetes, according to the report published in JAMA.

"There has been an increase in death rates among working age Americans," said Dr. Steven Woolf, director emeritus of the Center on Society and Health at Virginia Commonwealth University. "This is an emergent crisis. And it is a uniquely American problem since it is not seen in other countries. Something about life in America is responsible."

The rising rates of midlife mortality hit some regions of the country harder than others, Woolf and his co-author found. Increases were highest in northern New England and the Ohio Valley.

Economic hardship and the resulting despair may be to blame in those regions, Woolf suggested.

"While it's a little difficult to place the blame on despair directly, the living conditions causing despair are leading to other problems," he explained. "For example if you live in an economically distressed community where income is flat and it's hard to find jobs, that can lead to chronic stress, which is harmful to health."

Noting that a pattern of increasing mortality in middle age is not seen in other high-income countries, Woolf said this might be because "in other countries there are more support systems for people who fall on hard times. In America, families are left to their own devices to try to get by."

Stark regional differences

Data for the study came from the National Center for Health Statistics and the U.S. Mortality Database for 1959 to 2017. The researchers also scoured the medical literature for studies of U.S. life expectancy and mortality trends.

Based on the data, life expectancy had increased by almost 10 years over the course of nearly six decades — from 69.9 years to 78.9 years — but had been declining since 2014, to 78.6 years. And the overall decline was explained by increased mortality among the middle aged.

Death rates among the middle aged weren't uniform across the country. The largest relative increases in midlife mortality rates occurred in New Hampshire, 23.3 per cent, West Virginia, 23.0 per cent, Ohio, 21.6 per cent, Maine, 20.7 per cent, Vermont, 19.9 per cent, Indiana, 14,8 per cent and Kentucky, 14.7 per cent. Life expectancy actually increased or plateaued in some Western states, the researchers reported.

"The current problems we are seeing are decades in the making," Woolf said. "We used to have the highest life expectancy in the world. The pace at which life expectancy was increasing in the U.S. started to fall off relative to other countries in the 80s."

This is really evidence that mortality rates are increasing only in middle age while they're continuing to decline in children, adolescents and people over 65. - Dr. John Rowe, Columbia University Mailman School of Public Health

The new findings highlight some distressing trends, said Dr. John Rowe, a professor in Columbia University's Mailman School of Public Health in New York City.

"It is depressing," Rowe said, "but I don't think it's much of a surprise. We knew the opioid epidemic was taking a major toll with 250,000 who have overdosed and died."

What's striking is that the decline in life expectancy isn't the same for all age groups. "This is really evidence that mortality rates are increasing only in middle age while they're continuing to decline in children, adolescents and people over 65," Rowe said, noting that it's occurring as mortality rates from cancer and stroke are declining.

Part of the problem may be that middle-aged people are getting squeezed by health-care costs because they are less likely to have coverage than children and people over 65. In fact, another recent study found out-of-pocket costs were more likely to prompt middle-aged people to cut back on heart disease medications than people over 65.