As the legalization and decriminalization of marijuana continue to spread across the U.S., so too have usage rates for the drug, especially in younger demographics. Over the years, research into the long-term effects of marijuana usage has been paltry and difficult to undertake due to legal restrictions and social stigmas. Yet, a handful of researchers have taken strides to push the limits of various research endeavors, to better understand the underlying biology of cannabis’ effects on the body. This is exactly what a team of investigators at the Georgia State University (GSU) School of Public Health set out to accomplish, reporting their recent study findings in the European Journal of Preventive Cardiology in an article entitled “Effect of Marijuana Use on Cardiovascular and Cerebrovascular Mortality: A Study Using the National Health and Nutrition Examination Survey Linked Mortality File.”
“Steps are being taken toward legalization and decriminalization of marijuana in the United States, and rates of recreational marijuana use may increase substantially as a result,” explained lead study investigator Barbara Yankey, a doctoral candidate in the School of Public Health at GSU. “However, there is little research on the impact of marijuana use on cardiovascular and cerebrovascular mortality.”
Due to the lack of longitudinal data on marijuana use, the researchers designed a retrospective follow-up study of National Health and Nutrition Examination Survey (NHANES) participants aged 20 years and above. 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.
“We linked participants aged 20 years and above, who responded to questions on marijuana use during the 2005 US National Health and Nutrition Examination Survey to data from the 2011 public-use linked mortality file of the National Center for Health Statistics, Centers for Disease Control and Prevention,” the authors wrote. “Only participants eligible for mortality follow-up were included. We conducted Cox proportional hazards regression analyses to estimate hazard ratios for hypertension, heart disease, and cerebrovascular mortality due to marijuana use. We controlled for cigarette smoking and other relevant variables.”
In the current study, the research team estimated the associations of marijuana use, and duration of use, with death from hypertension, heart disease, and cerebrovascular disease, controlling for cigarette use and demographic variables, including sex, age, and ethnicity. Death from hypertension included multiple causes, such as primary hypertension and hypertensive renal disease. Among a total of 1213 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.
Interestingly, marijuana users had a higher risk of dying from hypertension. Compared to nonusers, marijuana users had a 3.42 times higher risk of death from hypertension and a 1.04 greater risk for each year of use. There was no association between marijuana use and death from heart disease or cerebrovascular disease.
Previous research has also shown that marijuana does increase the risk of stress-induced cardiomyopathy, lending weight to the growing evidence of the extended use of the drug and increased risk of cardiac injury—albeit more research is essential.
“We found that marijuana users had a greater than threefold risk of death from hypertension and the risk increased with each additional year of use,” Ms. Yankey noted. “Our results suggest a possible risk of hypertension mortality from marijuana use. 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.”
Amazingly, the authors commented that the cardiovascular risk associated with marijuana use might be greater than the cardiovascular risk already established for cigarette smoking.
“We found higher estimated cardiovascular risks associated with marijuana use than cigarette smoking,” Ms. Yankey concluded. “This indicates that marijuana use may carry even heavier consequences on the cardiovascular system than that already established for cigarette smoking. However, the number of smokers in our study was small, and this needs to be examined in a larger study.”