Cannabis — also referred to as marijuana — is a psychoactive drug that many people use for recreational purposes and its purported medicinal benefits. But what does recent research say about it? Do the risks trump the benefits?
At the time of writing this feature, in the United States, 36 states and four territories have legalized cannabis-derived products for medical use. Additionally, 18 states, two territories, and the District of Columbia allow the recreational use of cannabis.
Although many people use the terms “cannabis” and “marijuana” interchangeably, the latter has racist roots and connotations that go back to nearly a century ago.
According to the Pew Research Center, nine out of 10 Americans favor some form of legalization for cannabis. The same poll found that 18% of Americans, equating to 48.2 million people, have used cannabis in the last year, with 11% saying they have done so in the previous month. Fewer than half — 46% — say they have ever used cannabis.
According to the National Institutes of Health (NIH), people have used cannabis for
It is obvious that many people enjoy the euphoric effects of cannabis, using it for recreational purposes. That latest data suggest that
Cannabis is currently illegal at the federal level and is classed as a Schedule I controlled substance. This classification level states that a substance must have “no currently accepted medical use and a high potential for abuse.”
It is a controversial classification, as it places this drug in the same category as heroin, methaqualone, LSD, and MDMA, or ecstasy.
This has made rigorous clinical cannabis research in the U.S. difficult to conduct, and it can be hard for the average person to find conclusive information regarding its health effects.
With so many states having legalized cannabis, research is accelerating, however. The Food and Drug Administration (FDA) has voiced its
The FDA is charged with the development and safety of medical products and has therefore not explicitly addressed the health effects of recreational cannabis.
Speaking of the FDA’s position, Dr. Tom Curran, of Upstate Medical University in New York, told Medical News Today that “they have one foot on the accelerator and another on the brake.”
He pointed out that until recently, all the cannabis used in U.S. research has come from a single source: a growing facility at the University of Mississippi.
Some experts have questioned the value of this cannabis for research. Speaking to NPR, cannabis researcher Dr. Sue Sisley described it as “an anemic greenish powder,” adding that “it’s very difficult to overcome the placebo effect when you have something that diluted.”
As a result, any research based on the University of Mississippi’s research stock may underreport its effects — positive or negative — adding yet one more element of uncertainty to existing studies. Therefore, since May, the federal National Institute of Drug Abuse has begun a protracted process of contracting with other suppliers.
Dr. Curran noted that among the institutions that have publicly advocated the removal of such obstacles to high-quality cannabis research are the following:
Medical cannabis research: In search of answers
Whether a person is a recreational user or interested in cannabis for medical purposes, it is natural to seek assurances that it is safe to use. The best available source of such information is medical cannabis research that measures its possible benefits and risks.
In 2017, a review from the National Academies of Sciences, Engineering, and Medicine (NAS) assessed more than 10,000 scientific studies on the medical benefits and adverse effects of cannabis conducted throughout 2016. This research remains the most comprehensive reference for the health effects of cannabis.
In 2021, researchers attempted a similar review for data from 2016 to 2019. They concluded that “we identified few recent studies conducted within U.S. populations [that] were of substantial rigor and quality to move the evidence base forward for many clinical conditions.”
In this article, we look at the most recent credible research exploring the medical benefits of cannabis to identify its health benefits and risks in an attempt to answer what seems to be a simple question: is cannabis good or bad?
Before we proceed, we should address a common question: what is the relationship between cannabis and CBD, which come from the same plant, cannabis sativa? Are they the same thing?
No, they are not.
Cannabis sativa contains some 450 chemicals, among which are a family of 80–100 chemicals called cannabinoids. Cannabinoids interact with the brain’s endocannabinoid system, which regulates a variety of activities, including mood, sleep, memory, and appetite.
The main cannabinoids in the plant are:
- delta-9 tetrahydrocannabinol (THC), which is responsible for the psychoactive effects of cannabis
- cannabidiol (CBD), which is believed to be anti-psychoactive and may moderate or control anxiety, chronic pain, sleep issues, and addictive impulses
When people refer to cannabis, they are referring to both THC and cannabidiol, as well as any other compound of the cannabis sativa plant.
The FDA has so far approved four medications containing cannabinoids:
Cannabis sativa plants with minimal THC are generally referred to as hemp, the source of much CBD. According to a 2019 Gallup poll, 14% of Americans use CBD, and sales are predicted to exceed $61 billion by 2027.
There are a variety of medical claims in support of CBD, many of which have not yet been clinically confirmed, largely due to the obstacles that hinder cannabis research.
Research has suggested that cannabis may be of benefit in the treatment of certain conditions listed below.
One area that the 2017 NAS study looked at closely was the use of medical cannabis to treat chronic pain.
The research found that cannabis, or products containing cannabinoids, may effectively relieve neuropathic pain caused by damaged nerves.
However, beyond that, according to the
Depression, post-traumatic stress disorder, and social anxiety
It has been alleged that cannabis may help address depression, post-traumatic stress disorder (PTSD), and anxiety.
While some have proposed the use of cannabis as an antidepressant, a 2020 study found little evidence supporting this — instead, it found that the opposite is more likely true.
In March 2021, the first FDA-approved, placebo-controlled, double-blind
It reported that veterans who smoked cannabis experienced no greater improvement in the severity of their PTSD symptoms than those of a placebo group.
On the other hand, a nonplacebo study from December 2020 reported that veterans who smoked cannabis were 2.57 times more likely to no longer qualify as having PTSD.
A 2021 randomized, controlled trial found that smoking cannabis on days when alcohol is consumed
However, the 2017 NAS review cited concerns that cannabis use may lead to an increased risk of harmful use for and dependence on other substances.
The confirmed value of cannabinoids for people with cancer is that drugs, such as Marinol and Syndros, can relieve post-cancer chemotherapy nausea and vomiting.
There has been and continues to be a substantial amount of research exploring cannabis’ usefulness in fighting cancer.
Some promising results indicate that it can arrest the growth of
At the time of writing, a drug containing equal parts THC and cannabidiol and sold worldwide as Sativex is in the midst of phase 3 clinical trials in the U.S. as Nabiximols.
The drug is a second-line medication for situations where primary multiple sclerosis medicines do not satisfactorily relieve symptoms of spasticity.
However, no benefit from smoking cannabis has been clinically reported for treating symptoms of MS so far.
At the other end of the spectrum are studies that have investigated negative associations between cannabis use and health.
Mental health issues
There are anecdotal reports that smoking cannabis can help people with bipolar disorder (BD) alleviate its symptoms.
However, there is a substantial body of evidence that it is associated with more extreme bipolar episodes, as well as symptoms of psychosis, accelerated cycling between moods, suicide attempts, a reduction in long-term BD remission, increased disability, and poorer functioning overall.
Fortunately, these associations last only as long as cannabis smoking continues.
A June 2021 NIH study of adults aged 18–35 years identified a strong association between smoking cannabis and an
A meta-study of available research in 2020 concluded that THC
The primary conclusion of the analysis was that further research is necessary to better understand the relationship between cannabis and these disorders.
A 2017 study contained a curious finding among people with schizophrenia and other psychoses: a history of cannabis use was linked with improved performance on tests assessing learning and memory.
A study from the University of Queensland published in January 2021 looked at how smoking cannabis regularly can affect people’s lives. The study found that individuals who smoked daily or weekly were more likely to:
- partake in high risk alcohol consumption
- smoke cigarettes
- take other illicit drugs
- not be in a relationship at 35 years of age
- be depressed
- not have a job
Cannabis use disorder
While cannabis is not classically addictive, there is evidence that the more someone uses the substance, the more likely they are to develop a dependence on it, referred to as “cannabis use disorder.”
According to the CDC,
Testicular and lung cancer
The 2017 NAS study identified evidence suggesting an increased risk for the slow-growing seminoma subtype of testicular cancer.
The study concludes that further epidemiological study of the possible connection to cannabis is warranted, perhaps incorporating smoke-free vaping as an ingestion vehicle.
The same ingredients may also increase the risk of lung cancer when cannabis is smoked as opposed to eaten or vaped. However, the NIH’s National Institute of Drug Abuse reports there is little convincing evidence of a link between cannabis and lung cancer:
“While a few small, uncontrolled studies have suggested that heavy, regular [cannabis] smoking could increase [the] risk for respiratory cancers, well-designed population studies have failed to find an increased risk of lung cancer associated with [cannabis] use.”
Regular cannabis smoking has been linked to an increased risk of chronic cough, but it is unclear whether smoking cannabis worsens lung function or increases the risk of chronic obstructive pulmonary disease or asthma.
There is evidence that demonstrates both the health benefits and adverse effects of cannabis. It is also apparent that some claims of the substance’s effects may be overstated at best and inaccurate at worst.
While many people enjoy smoking cannabis recreationally, it is clear that more and better research is needed to understand its health effects fully.
If you happen to live in a state where the use of cannabis is legal, you and your doctor should carefully consider the various reported benefits and risks and how they relate to your illness and health history before using the substance.
Additionally, remember to always speak with your doctor before taking any new medicine.