A new study claims marijuana is tied to a 3-fold higher risk of dying from high blood pressure - but there's a catch

• A new study claims marijuana users face a three-fold higher risk of dying from hypertension than non-users.
• The study has some limitations, including the fact that it defines users as anyone who's ever tried the drug.
• Still, the study highlights an important area for more future research: marijuana's impact on the heart.

A new study suggests that anyone who smokes marijuana faces a three-fold greater risk of dying from high blood pressure than people who have never used the drug.

Those findings sound alarming, but it's important to keep in mind that, like any study, this one has limitations. Those include the fact that it defines marijuana "users" as anyone who's ever tried the drug, and doesn't differentiate between multiple strains of a highly unregulated product.

Overall, however, the study does highlight some key areas for future study - including how using cannabis might impact the heart. Here's what you need to know.

'A greater than three-fold risk of death'

"We found that marijuana users had a greater than three-fold risk of death from hypertension and the risk increased with each additional year of [cannabis] use," Barbara Yankey, the lead author of the study and a doctoral student of epidemiology and biostatistics at Georgia State University, said in a statement.

For her paper, published Wednesday in the European Journal of Preventive Cardiology, Yankey looked at more than 1,200 people aged 20 or older who had been recruited previously as part of a large and ongoing national health survey. In 2005, researchers asked them the following question: "Have you ever used marijuana or hashish?". People who answered "yes" were classified as marijuana users; those who answered "no" were classified as non-users.

They then merged that data with statistics on death from all causes (pulled from the US National Center for Health Statistics), and adjusted it to rule out any factors that could muddle the results, like gender, race, and a history of smoking tobacco.

Overall, those classified as marijuana users were found to be 3.42 times more likely to die from hypertension, or high blood pressure, than those who said they had never used. That risk also appeared to rise 1.04 times with what the researchers labeled "each year of use."

Here's the problem: the study authors defined anyone who said they had ever tried marijuana as a "regular user."

Other research suggests this is a poor assumption. The majority of Americans (about 52%, according to a recent estimate) say they have tried cannabis at some point. Yet only 14% say they use the drug "regularly," something the survey defined as "at least once a month."

Also, the study was observational, meaning that it followed a group of people over time and reported on what happened to them.

That means the researchers cannot conclude a cause and effect - they can't say that smoking marijuana causes high blood pressure; only that the two things appear to be linked. As the authors wrote in their study: "From our results, marijuana use may increase the risk for hypertension mortality."

Another issue is the unregulated nature of the existing (largely illegal) cannabis market. People are using a wide variety of strains whose concentrations of compounds (there are up to 400 in marijuana, including THC and CBD) can differ drastically.

"There are so many strains of [marijuana] out there, with no quality standards … making it tough to generalize the effects," Charles Pollack, who directs the Lambert Center for the Study of Medicinal Cannabis and was not involved with the new study, told LiveScience.

Marijuana and your heart

While the study is far from conclusive, it does shed light on an important potential health risk linked with marijuana use. Scientists know that cannabis has some impacts on the heart, but because of the limited research available on the drug, it has been hard to suss out how marijuana effects things like high blood pressure.

We know, for example, that ingesting marijuana increases heart rate by somewhere between 20 and 50 beats a minute for anywhere from 20 minutes to three hours, according to the National Institute on Drug Abuse. But a large, recent report from the National Academies of Sciences, Engineering, and Medicine found "insufficient evidence" to support or refute the idea that cannabis might increase overall risk of a heart attack. The same report also found some limited evidence that using the drug could be a trigger for the phenomenon, however.

When it comes to cannabis' effect on blood pressure, the results are also pretty inconclusive. One very small study, for example, found a sharp increase in blood pressure immediately after regular pot users stopped using the drug. "Abrupt cessation of heavy cannabis use may cause clinically significant increases in blood pressure in a subset of users," the researchers wrote in their study. And according to the Mayo Clinic, using cannabis could result in decreased, not increased blood pressure.

Hopefully this new study will be the first of many more to come.