Medical marijuana, which refers to the use of the whole, unprocessed marijuana plant or its extracts for medicinal purposes, has generated a lot of excitement for its potential role in treating diseases ranging from anorexia to Alzheimer’s.1
While the plant has impressive medicinal properties that are still being explored, emerging research also suggests that frequent cannabis use may be linked to heart risks, including an increased risk of heart attack and stroke.
The findings highlight the need for increased research into the most effective dosages and routes of administration for medical marijuana while also pointing to potential dangers for frequent recreational users.
Frequent Cannabis Use Linked to Erratic Heartbeat
In the first preliminary study, presented at a 2019 meeting of the American Heart Association (AHA) in Philadelphia, young people diagnosed with a cannabis (marijuana) use disorder had a 47% to 52% greater risk of being hospitalized for irregular heartbeat, also known as arrhythmia, compared to those without the disorder.2
It’s estimated that 2.5% of U.S. adults, or nearly 6 million people,3 may struggle with cannabis use disorder, a condition characterized by cravings for cannabis, recurrent cannabis use that leads to problems at school, work or home, unsuccessful efforts to cut down on cannabis use and other factors.
Generally speaking, the disorder is defined as, “A problematic pattern of cannabis use leading to clinically significant impairment or distress.”4 For the study, researchers used data from more than 67.5 million hospital patients, revealing that those aged 25 to 34 who compulsively used cannabis were 52% more likely to be hospitalized for irregular heartbeat, as were 28% of compulsive cannabis users aged 15 to 24.5
The effects on heartbeat depended on the dose, according to Dr. Rikinkumar Patel of Griffin Memorial Hospital in Norman, Oklahoma, who said in an AHA news release:6
“The effects of using cannabis are seen within 15 minutes and last for around three hours. At lower doses, it is linked to a rapid heartbeat. At higher doses, it is linked to a too-slow heartbeat …
The risk of cannabis use linked to arrhythmia in young people is a major concern, and physicians should ask patients hospitalized with arrhythmias about their use of cannabis and other substances because they could be triggering their arrhythmias.
Young Cannabis Users at Increased Risk of Stroke
The second study, which was also presented at the 2019 meeting of the AHA in Philadelphia, involved more than 43,000 adults between the ages of 18 and 44. Nearly 14% had reported using cannabis in the previous 30 days.
Among those who used cannabis for more than 10 days a month, stroke risk increased by nearly 2.5 times compared to nonusers.7 Frequent cannabis users who also smoked cigarettes or used e-cigarettes had an even greater risk of stroke — more than three times that of nonusers. Lead study author Tarang Parekh of George Mason University in Fairfax, Virginia, explained in a news release:8
“Young cannabis users, especially those who use tobacco and have other risk factors for strokes, such as high blood pressure, should understand that they may be raising their risk of having a stroke at a young age … Physicians should ask patients if they use cannabis and counsel them about its potential stroke risk as part of regular doctor visits.”
The study was observational in nature and does not prove that using cannabis caused the increased stroke risk, only that an association exists. However, past research has also found links between cannabis use and heart risks, as smoking marijuana is known to increase heart rate and blood pressure, and may increase the risk of heart attack in young men.9
This is particularly true in the first hour after marijuana usage, when the risk of heart attack by increase by a factor of 4.8. Daily marijuana users may also increase their annual risk of heart attack from 1.5% to 3% per year,10 possibly due to coronary arterial vasospasm, which is a muscle constriction of the coronary artery.
Cannabis Use Increases Heart Attack Risk in Youth
A separate study aimed at evaluating the risk of various substances on heart attacks in youth aged 15 to 22 years also found that cannabis increased the risk.11 Cannabis users in this age group had a 30% higher risk of heart attack compared to nonusers, while cocaine users’ heart attack risk was 3.9 times higher, and amphetamine users’ 2.3 times higher, compared to nonusers of those drugs.12
Further, 14.7% of cannabis users had severe illness when they were admitted — a higher proportion of severe illness cases compared to cocaine and amphetamine users. Cannabis users also had a higher mean total charge for their stay, coming in at $53,608.13
“Our study demonstrates a higher prevalence and a significant odds ratio of (acute heart attack) in the younger population with cannabis use, along with the potential cost burdens because of severity of illness, extended length of hospitalization, and higher use of treatment modalities,” the researchers noted.14
What’s more, 2% of the cannabis users who were hospitalized for heart attacks died during their stays, compared to none of the other drug users.15 It’s an interesting finding, particularly since lethal overdoses from cannabis and cannabinoids do not occur, as there are no cannabinoid receptors in the brainstem areas that control respiration.16
How Do Cannabinoids Affect Your Cardiovascular System?
While research suggests marijuana use may not significantly affect long-term mortality, people with a history of heart disease or heart problems may be at increased risk of marijuana’s heart effects, in part due to the actions of cannabinoids. Cannabis contains more than 100 unique cannabinoids, which bind to receptors in your body.
Cannabinoids interact with your body by way of naturally occurring cannabinoid receptors embedded in cell membranes throughout your body. There are cannabinoid receptors in your brain, lungs, liver, kidneys, immune system and more; the therapeutic (and psychoactive) properties of marijuana occur when a cannabinoid activates a cannabinoid receptor.
Tetrahydrocannabinol (THC), the compound responsible for marijuana’s psychoactive effects, is one type of cannabinoid. Cannabidiol (CBD), the nonpsychoactive component of cannabis, is another, which has previously been found to offer many benefits for pain relief, seizures and other health conditions. As far as your heart health is concerned, Harvard Medical School noted:17
“One of the few things scientists know for sure about marijuana and cardiovascular health is that people with established heart disease who are under stress develop chest pain more quickly if they have been smoking marijuana than they would have otherwise.
This is because of complex effects cannabinoids have on the cardiovascular system, including raising resting heart rate, dilating blood vessels, and making the heart pump harder. Research suggests that the risk of heart attack is several times higher in the hour after smoking marijuana than it would be normally.
While this does not pose a significant threat to people who have minimal cardiovascular risk, it should be a red flag for anyone with a history of heart disease. Although the evidence is weaker, there are also links to a higher risk of atrial fibrillation or ischemic stroke immediately following marijuana use.”
Is Cannabis Linked to Schizophrenia?
Another area that deserves more research is marijuana’s potential link to mental health disorders, including schizophrenia. Cannabis use is associated with schizophrenia, particularly in young people who use it frequently.18
There could be a genetic variable at play as well, as if you have a type of AKTI gene, your risk of developing a psychotic disorder if you use cannabis increases. This is again intensified in frequent users, as daily cannabis users who have the genetic variant have a sevenfold increased risk of psychosis compared with daily users who do not have the genetic variation.19
It’s also been suggested that cannabis use by adolescents and young adults may increase the risk of schizophrenia in later life. Researchers wrote in World Psychiatry:20
“There is now reasonable evidence from longitudinal studies that regular cannabis use predicts an increased risk of schizophrenia and of reporting psychotic symptoms. These relationships have persisted after controlling for confounding variables such as personal characteristics and other drug use.
… A contributory causal relationship is biologically plausible because psychotic disorders involve disturbances in the dopamine neurotransmitter system with which the cannabinoid system interacts, as has been shown by animal studies and a human provocation study.”
Medical Marijuana Benefits
While there are risks to cannabis use to be aware of, through traditional plant breeding techniques and seed exchanges, growers have started producing cannabis plants that have higher levels of CBD and lower levels of THC for medical use.
It’s likely that both THC and CBD have a beneficial role in health. One study even found that CBD may buffer some of the psychoactive effects of THC and the two compounds may offer greater therapeutic results when administered together than alone.21
In states where medical cannabis is legal, its use may be allowed under certain medical circumstances only, and some allow only CBD oils or pills. What are people using it for? Pain and anxiety are top uses, but there is also potential for its use as a cancer treatment22 and much more, as cannabinoids have shown promise for a variety of medical uses, including:23
Irritable bowel syndrome
Chemotherapy-associated nausea and vomiting
Inflammatory and neuropathic pain
Post-traumatic stress disorder
Further, THC may offer hope for treating Alzheimer’s disease, according to a study on mice.24 A low dose of THC even reversed age-related decline in cognitive performance of mice aged 12 and 18 months.25
Cannabinoids May Benefit Heart Health and More
The fact is, it’s cannabinoids’ versatility that makes them so exciting. While cannabis has been linked to some heart risks, CBD has been found to lower blood pressure during times of stress26 and protect stroke patients from brain damage.27
Because cannabinoids work via multiple mechanisms, it’s possible they could be useful not only for certain aspects of heart health and Alzheimer’s but also for Parkinson’s disease, brain tumors, epilepsy and traumatic brain injury. Researchers writing in Frontiers in Integrative Neuroscience noted:28
“The inherent polypharmaceutical properties of cannabis botanicals offer distinct advantages over the current single-target pharmaceutical model and portend to revolutionize neurological treatment into a new reality of effective interventional and even preventative treatment.”
If you’re considering the use of medical marijuana, and you live in a state where it’s legal, you can get a recommendation for a medical cannabis card from your physician, then join a collective, which is a group of patients that can grow and share cannabis medicines with each other. By signing up as a member, you gain the right to grow and share your medicine.
There are different ways to administer medical marijuana, ranging from inhalation, vaporization and smoking to sublingual (under the tongue), oral ingestion and topically. The best form for you will depend on your medical needs, so ideally work with an experienced physician to determine the best route of administration and dosage.
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