People who smoke weed are three times more likely to die from high blood pressure than those who do not, new research suggests.
Scientists in the US analysed data from marijuana users against non-users to determine the risk of death from hypertension (high blood pressure).
They found that compared to non-users, marijuana users had a 3.42-times higher risk of death from hypertension.
The researchers also found that the amount of time a person has spent smoking weed makes a difference, with a 1.04-times greater risk for each year of use.
However, Dr Willie Lawrence, an interventional cardiologist and spokesperson for the American Heart Association, has called the research “flawed”.
Lead author Barbara Yankey, a PhD student at Georgia State University, Atlanta, investigated the subject due to ongoing debate about the legalisation of marijuana in the US.
“Steps are being taken towards legalisation and decriminalisation of marijuana in the United States and rates of recreational marijuana use may increase substantially as a result,” she said.
“However, there is little research on the impact of marijuana use on cardiovascular and cerebrovascular mortality.”
The researchers conducted a retrospective follow-up study of NHANES (National Health and Nutrition Examination Survey) participants aged 20 years and above to gather results.
In 2005-2006, participants were asked if they had ever used marijuana. Those who answered “yes” were considered marijuana users. Participants reported the age when they first tried marijuana and this was subtracted from their current age to calculate the duration of use.
Information on marijuana use was merged with mortality data in 2011 from the National Centre for Health Statistics.
The researchers estimated the associations of marijuana use and duration of use, with death from hypertension, heart disease, and cerebrovascular disease (a vascular disease caused by problems with blood supply to the brain), controlling for cigarette use and demographic variables including sex, age and ethnicity.
Among a total of 1,213 participants, 34% used neither marijuana nor cigarettes, 21% used only marijuana, 20% used marijuana and smoked cigarettes, 16% used marijuana and were past-smokers, 5% were past-smokers and 4% only smoked cigarettes. The average duration of marijuana use was 11.5 years.
The study concluded that marijuana users had a three times higher risk of dying from hypertension. There was no link between marijuana use and death from heart disease or cerebrovascular disease.
Yankey pointed out that there were limitations to the way marijuana use was estimated. For example, it cannot be certain that participants used marijuana continuously since they first tried it.
“Our results suggest a possible risk of hypertension mortality from marijuana use,” she said. “This is not surprising since marijuana is known to have a number of effects on the cardiovascular system.
“Marijuana stimulates the sympathetic nervous system, leading to increases in heart rate, blood pressure and oxygen demand. Emergency rooms have reported cases of angina and heart attacks after marijuana use.”
The authors stated that the cardiovascular risk associated with marijuana use may be greater than the risk already established for cigarette smoking.
“This indicates that marijuana use may carry even heavier consequences on the cardiovascular system than that already established for cigarette smoking,” said Yankey.
“However, the number of smokers in our study was small and this needs to be examined in a larger study.
“Needless to say, the detrimental effects of marijuana on brain function far exceed that of cigarette smoking.”
Yankey said it was crucial to understand the effects of marijuana on health so that policy makers and individuals could make informed decisions.
“If marijuana use is implicated in cardiovascular diseases and deaths, then it rests on the health community and policy makers to protect the public,” she concluded.
Dr Willie Lawrence called the research “flawed” as the study was based on a self-reported survey and did not include information about the amount of marijuana people used or an accurate overview of how long they had used it.
“Everything in life is dose-dependent and duration-dependent, and those kind of questions are not answered in a study like this,” he said, according to United Press International.
“There’s also no way to tell whether a person had been using other drugs that could affect their blood pressure, or whether their pot was laced with another substance.
“It could be these elevations in blood pressure are a manifestation of marijuana being laced with other things that are more cardio-stimulating.”
The study is published in the European Journal of Preventive Cardiology.