The increasing rate of deaths due to opioids, alcohol and suicides are part of a public health crisis described as “deaths of despair” in a new report published this week.

Life expectancy in the United States has decreased for the second year in a row because of these factors, researchers wrote in BMJ. The drop was particularly steep among middle-age white Americans and people living in rural areas, USA Today reports.

“Why white Americans are dying at higher rates from drugs, alcohol, and suicides is unclear, complex, and not explained by opioids alone,” the researchers wrote. They note that possibilities include the collapse of industries and the local economies they supported, the erosion of social cohesion and greater social isolation, economic hardship, and distress among white workers over losing the security their parents once enjoyed.