A new study by the American Heart Association (AHA) reveals that smoking marijuana causes "substantial risks" to cardiovascular health, including increasing the chances of suffering a heart attack, stroke or other cardiovascular problems.
The AHA's study, published in a scientific paper in its flagship journal Circulation on Wednesday, was careful to observe that cannabis also has "potential therapeutic and medicinal properties," thanks to its famous compounds, THC and CBD. After reviewing the growing national and international efforts to decriminalize or legalize both recreational and medicinal marijuana, the authors noted that the chemicals in marijuana are associated with increased risks of atrial fibrillation (irregular heartbeats), heart failure and heart attacks, and that marijuana use has been associated with a greatly increased likelihood of stroke.
There are differences in how specific cannabinoids (chemicals found in cannabis) impact the body. The authors found that smoking THC (which produces an intoxicating effect) may induce abnormalities in heart rhythm, including atrial fibrillation, ventricular arrythmias, tachycardia and premature ventricular contractions. By contrast, CBD (which does not produce an intoxicating effect) can reduce one's heart rate, open up the arteries, lower blood pressure and reduce inflammation, which is linked to atherosclerosis and strokes.
The authors also noted that the act of smoking or vaping marijuana may increase the health risks associated with the drug, increasing the concentrations of carbon monoxide and tar in a manner analogous to smoking tobacco. At the same time, they observed that some clinicians believe marijuana use can help for treating neuropathic pain (typically associated with type 2 diabetes), decreasing prescription drug use and assisting patients suffering from age-related diseases like Alzheimer's and Parkinson's. The authors warned older potential users that, despite these potential benefits, marijuana use could also increase the risk of angina and interfere with a variety of cardiovascular and mental health medications.
"The purpose of our study was to explore the evidence and science in order to provide physicians and health care workers with the information that is available on the effects of marijuana, especially on the cardiovascular system," Dr. Robert Kloner, a co-author of the paper and chief science officer and scientific director of cardiovascular research at Huntington Medical Research Institutes, told Salon by email. "We have tried to provide a balanced paper that reviews both potential benefits but also covers some of the concerns about its effect on the cardiovascular system.
"An analogy might be to look at alcohol," Kloner continued. "Alcohol is legal but has both some positive and negative effects on the cardiovascular system. It is important for physicians and consumers to have information about what those positive and negative effects are so that they can make intelligent choices in their own lives as to whether and how to use alcohol. The same arguments can be applied to marijuana."
Kloner's observation about "the information that is available" on marijuana is reflected in the paper, which emphasized that there has not been enough research on the drug to comprehensively understand its impact on the human body.
"The public needs high-quality information about cannabis, which can help counterbalance the proliferation of rumor and false claims about the health effects of cannabis products," the authors write. "Furthermore, research funding must be increased proportionally to match the expansion of cannabis use, not only to clarify the potential therapeutic properties but also to better understand the cardiovascular and public health implications that now follow the decriminalization of cannabis."
Salon reached out to marijuana legalization advocates for their thoughts on the new paper's implications.
"It has long been acknowledged that cannabis is a mood-altering substance with some risk potential," Paul Armentano, deputy director of the National Organization for the Reform of Marijuana Laws (NORML), told Salon by email. He noted that prohibition of marijuana does not make sense given that whatever its risks, pot is not more dangerous than alcohol, tobacco and certain prescription medications. "By any rational assessment, the continued criminalization of cannabis is a disproportionate public policy response to behavior that is, at worst, a public health concern," Armentano continued. "But it should not be a criminal justice matter. These latest statements from the AHA do little if anything to change this fact."
Morgan Fox, media relations director at the National Cannabis Industry Association (NCIA), expressed concern that anti-marijuana advocates would seize on the report to further vilify the drug.
"Such broad studies are frequently used by proponents of the failed status quo to argue against further sensible cannabis reforms, but they consistently gloss over the fact that millions of people have and will continue to consume cannabis regardless of its legal status," Fox wrote by email. "Keeping the cannabis market underground and unregulated merely perpetuates and exacerbates public health and safety problems, and makes research much more difficult."
Dr. Sheila Vakharia, deputy director of the Department of Research & Academic Engagement for the Drug Policy Alliance, had a slightly different take.
"I am not concerned about anti-legalization advocates using this report against us," Vakharia argued by email. "Instead, it bolsters the very policies that the Drug Policy Alliance advocates for — the report clearly states that it is essential to remove marijuana from schedule 1 and states that a regulated and taxed market is best for public health and safety."
Vakharia noted that the AHA's study itself listed the "known, purported, and possible medical benefits" associated with marijuana use. Pot is known to reduce pain, can serve as an antiemetic, relieves certain symptoms of multiple sclerosis, treats cachexia (the wasting away of the body due to a severe illness) and is helpful to patients with epilepsy. There is also inconclusive evidence suggesting that marijuana can help with the muscular condition dystonia, the eye condition glaucoma and certain mental illnesses, like anxiety and depression. The Marijuana Policy Project (which Vakharia also referred to) claims in its model medical marijuana bill that the drug can also be prescribed for cancer, hepatitis C, AIDS/HIV, Crohn's disease or ulcerative colitis, certain types of autism and post-traumatic stress disorder (PTSD).
"The greatest harm associated with marijuana use is its criminalization," Vakharia told Salon when asked if the prohibition on the drug can be viewed as a public health problem. Despite widespread legalization, she said, arrests for marijuana possession still represent more than one-third of all drug-related arrests in the country. "The collateral consequences of a drug-related arrest can deprive you of opportunities for life — including access to federal financial aid for higher education, potential denial of job opportunities or certain professional licenses, being unable to live in public housing or access some social welfare benefits, and so much more."
As Fox pointed out, legalizing marijuana could also assist the government in regulating the drug, which in turn would help keep it out of the hands of minors.
"Licensed cannabis providers have a strong incentive not to sell cannabis to minors and obey all applicable state laws, whereas illicit dealers do not," Fox explained. "Regulated markets also have tools to ensure that retailers are in strict compliance, which does not occur in the underground market. Most states also use cannabis tax revenue to fund public education, which is often targeted at minors."
Armentano had a similar observation. "A pragmatic regulatory framework that allows for the legal, licensed commercial production and retail sale of marijuana to adults but restricts and discourages its use among young people — coupled with a legal environment that fosters open, honest dialogue between parents and children about marijuana's potential harms — best reduces the risks associated with the plant's use or misuse," Armentano wrote. "By contrast, advocating for marijuana's continued criminalization only compounds them."
Although public opinion now overwhelmingly favors legalization, both President Trump and his Democratic opponent, former Vice President Joe Biden, continue to oppose it.