The U.S. death rate rose for the first time in a decade, according to a preliminary report from the Centers for Disease Control and Prevention.

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In the report released by the CDC last week, researchers found that more Americans died last year than any other time in the last 10 years. In 2015, the death rate rose to nearly 730 deaths per 100,000 people, a jump from 723 deaths per 100,000 people in 2014, the Associated Press reported. The last time the death rate "jumped" was in 2005, according to Fortune.

This goes against the general recent trend of falling death rates, which have been influenced by the advent of "better medical technology and disease management," Fortune explained. Better medical technology has particularly been effective at "slowing the number of cancer-related deaths," Fortune reported, which have been at their lowest in recent years.

CDC researchers emphasized that the report is just preliminary and that the data could be a "blip."

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“There’s no smoking gun here,” Farida Ahmad, mortality surveillance lead at the National Center for Health Statistics at the CDC, told the Washington Post. “It’s something that we’re going to be looking into, and watching to see if it holds for 2016. It could be that it’s just a blip as it was 10 years ago.”

Although researchers are looking to see if these findings hold for 2016, Ahmad said there is evidence in the data to draw a conclusion about the overall U.S. death rate.

The final data will be out later this year, according to the New York Times.

“It’s an uptick in mortality and that doesn’t usually happen, so it’s significant," Robert Anderson, the chief of mortality statistics at the National Center for Health Statistics, part of the Centers for Disease Control and Prevention told the Times. “But the question is, what does it mean? We really need more data to know. If we start looking at 2016 and we see another rise, we’ll be a lot more concerned.”

Many factors have contributed to the rise in death rate. Of the causes of death that increased, these three were most interesting to ATTN:.

1. Drug overdoses

"Since 2000 the rate of deaths from drug overdoses has increased by 137 percent including a 200 percent in the rate of overdose death involving opioids," according to a separate report from the CDC. More than 61 percent of all overdose involve opioids, CNN reported. The most common opioids involved in drug overdoses are Methadone, Oxycodone, and Hydrocodone.

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According to Business Insider, the recent CDC report found that "the age-adjusted drug overdose rate for all types of drugs for 2015 was 15.2 in 2015, compared to 14.1 in 2014."

2. Suicide

Suicide is the tenth leading cause of death in America, causing more than 42,000 Americans to die; year, according to the American Foundation for Suicide Prevention. The annual age-adjusted suicide rate is 12.93 per 100,000 deaths, with men 3.5 times more likely to commit suicide than women.

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According to Business Insider, a previous CDC report found that more Americans were dying by suicide than at any time in the last 30 years.

3. Alzheimer's disease

Alzheimer's disease is the sixth leading cause of death in the U.S., killing more than breast cancer and prostate cancer combined, according to the Alzheimer's Association. Currently there are more than 5 million people living with Alzheimer's disease, and by 2050 the number of people 65 or older living with Alzheimer's disease is projected to reach 13.8 million. Age and genetics are two of the greatest factors that places someone at risk of contracting the disease; nearly 1 in 3 people 85 or older have Alzheimer's disease, according to the Alzheimer's Association.