The US death rate just rose for the first time in a decade for an alarming reason

The American death rate has risen for the first time in ten years.

According to preliminary data from the Centers for Disease Control and Prevention, a greater portion of the population died in the United States last year than in any other year for a decade.

The cause? Deaths from drug overdoses (many of which are legal), suicide, and Alzheimer's disease.

This marks a sharp contrast from a decade-long trend toward lower death rates, a positive shift driven largely by improvements in health treatments and access to care.

A bigger killer of Americans than heroin

In 2014, opioid painkillers like OxyContin and Vicodin killed more Americans than heroin. Despite being perfectly legal with a doctor's prescription, opioid painkillers operate similarly to heroin in the brain and body - and they can be addictive.

In fact, many experts have said these drugs may open the door to later heroin use. A 2015 CDC report found that people who had abused opioid painkillers were 40 times as likely to abuse heroin as those who had not.

Nevertheless, the drugs are prescribed frequently. Health care providers wrote 259 million prescriptions for them in 2012, according ot the CDC. That's enough for every US adult to have a bottle of the pills.

Unfortunately, there are currently no standards of medical care for treating addiction in this country.

"Unlike what we see in other chronic conditions, such as diabetes and cardiovascular disease, there currently exists no road map of evidence-based best practices for physicians to follow to effectively and efficiently treat substance use disorders like opioid addiction," Douglas Nemecek, the chief medical officer of behavioral health for US health insurer Cigna, told Business Insider. The insurer unveiled an ambitious plan last month that aims to curb prescriptions for opioid painkillers by 25%.

"We know there are too many prescriptions being written for these drugs today that are not necessary, and our goal is really to eliminate those," said Nemecek.

Other disturbing factors behind the rise

Drug overdoses are not the only factor behind the rise in the US death rate. Suicide and Alzheimer's are also fueling the increase.

A CDC report released in April found that more Americans are dying by suicide today than at any other point in the past three decades. The rate has been steadily on the rise since 1999. Suicide is among the leading causes of death for both adolescents and young adults, but it's rising among middle-aged Americans as well.