THURSDAY, Sept. 20, 2018 (HealthDay News) -- The opioid epidemic has been front-page news for a few years now, with rising overdose deaths driving an overall decrease in Americans' average life expectancy.

But a new study suggests that the opioid epidemic is, in fact, nothing new.

Death rates from drug overdoses in the United States have been on an exponential growth curve that dates back at least to the early 1980s, researchers report.

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"We found the epidemic has been continually growing in a predictable pattern for almost four decades now," said senior study author Dr. Donald Burke, dean of the University of Pittsburgh's Graduate School of Public Health.

"The number of deaths increase every year by about 8 percent, and that continues," Burke said.

But this steady trend has been masked by the fluid nature of America's illicit drug culture, Burke and his colleagues found.

"When we tried to look at this smooth continuous exponential growth, we found that the epidemic has been changing. The drugs change, the demographics of who's dying changes, the locations change," Burke said. "You have this paradox of the overall curve is a smooth growth process, but it's composed of all these different sub-epidemics."

For this study, researchers collected nearly 600,000 individual reports of drug overdose deaths maintained by the U.S. National Vital Statistics System since 1979. That's the year drug overdoses began to be reported in their own category on death certificates, Burke explained.

During the past four decades, deaths from drug overdose plot as a near-perfect curve. Each year's total overdose count falls almost exactly on a smooth upward exponential curve, researchers said.

But looking closer at overdose death rates for individual drug types, which has been tracked since 1999, researchers found that what appeared to be a smooth and predictable trend was anything but.

Instead, drugs like cocaine and heroin and methamphetamine go in and out of vogue, year by year and decade by decade.

What is now known as the "opioid epidemic" actually started in the mid- to late-1990s, when doctors began overprescribing opioid painkillers, Burke said.

State and federal lawmakers responded by toughening restrictions on opioid prescribing. This drove people hooked on opioid painkillers to take up the cheaper option of heroin. Since then, users have migrated to even cheaper and deadlier synthetic opioids like fentanyl.

"Particularly in the last seven or eight years, there has been a marked explosion in the number of heroin and fentanyl users," Burke said. Heroin also used to be confined mainly to metropolitan areas on either coast; now it's being used in small towns across the country.

The findings were published Sept. 20 in the journal Science.

The new study shows "how attempts to reduce drug overdose deaths are severely undermined by our nation's failure to address addiction with effective, evidence-based prevention and treatment approaches," said Linda Richter, director of policy research and analysis with the Center on Addiction, a national nonprofit organization.

"We typically focus our efforts -- most of which are underfunded and frequently not supported by scientific evidence -- on the scariest drug trend of the day, and we wait to respond until overdose deaths reach epidemic levels," Richter said.

"We throw a variety of interventions at the problem and then don't bother to devote the time and resources necessary to assess whether those interventions even work," she said.

Why do overdose deaths continue to rise? Burke said it's likely a combination of "push" and "pull" factors on either side of the illicit drug market.

On the "push" side, Burke noted that innovation is on the side of drug suppliers.

"Everything that is on the supply side helps make drugs more available," Burke said. "The cost of producing the drugs is getting cheaper, the actual sales price is cheaper, the purities are increasing, the technologies for delivery, communication is easier -- and that applies not to any one drug, but to drugs across the board."

On the "pull" side, American society seems to be evolving in ways that could promote drug use.

"There's widening economic disparity, with many people having lost a sense of purpose in daily life," Burke said. "There's been a dissolution of our sense of community, particularly in small towns.

"It raises questions about what the future is going to hold," Burke said. "The main issue we raise is, if we don't address these deeper social determinants, are we really going to be able to change the trajectory of the epidemic?"

Richter agreed that a renewed focus on prevention is needed to block this ever-rising tide.

"A smarter, more effective approach would be to implement a comprehensive, sustained and evidence-based approach to addiction prevention, early intervention and treatment that we invest in for the long-term," Richter said. "This approach would involve broad-based prevention that addresses all addictive substances and the reasons people use them, as well as significant changes in how addiction treatment is delivered in the United States."

More information

The U.S. National Institute on Drug Abuse has more about the opioid overdose crisis.