The new average life expectancy for Americans is 78.7 years, which puts the U.S. behind other developed nations and 1.5 years lower than the Organisation for Economic Cooperation and Development (OECD) average life expectancy of 80.3. The OECD is a group of developed countries that includes Canada, Germany, Mexico, France, Japan, and the U.K.

So why has the U.S., a global leader in the length of life for its citizens in the 1960s, fallen so far in this metric for quality of the nation’s health?

A new study published in the BMJ journal looked into a broader cause behind the decline: despair.

“We are seeing an alarming increase in deaths from substance abuse and despair,” said Steven Woolf, an associate professor of emergency medicine at Virginia Commonwealth University and co-author of the report.

He added that the amount of the decrease in life expectancy is actually less alarming than the fact that addiction and a decline in the emotional wellbeing of Americans have been significant enough to drag down the country’s average length of life.

The research points to the opioid epidemic, backing up a CDC report from last year that linked the drop directly to a 21% increase in overdose deaths from the year before and cited a 137% increase in opioid-related deaths between 2000 and 2014.

The increase in deaths caused by drugs and alcohol, particularly among white Americans, is “unclear, complex, and not explained by opioids alone,” according to Woolf.

On average, 115 people in the U.S. die each day from an opioid overdose, and six Americans per day are dying from alcohol abuse—the highest rate in 35 years, according to federal data.

The report also highlights a rise in the suicide rate, which increased 24% between 1999 and 2014, as well as health conditions from diabetes to HIV/AIDS that are negatively impacting the lives of Americans.

The authors of the study point out that the solutions to problems politicians recognize as detrimental to the quality of life in the U.S. are often rejected when it comes down to policy making, and it’s American citizens who feel the impact of inaction.

“The consequences are dire: not only more deaths and illness but also escalating health care costs, a sicker workforce, and a less competitive economy,” the authors wrote. “Future generations may pay the greatest price.”