People have been using marijuana for a variety of health conditions for around 3,000 years. But if you’re tracking medical marijuana research studies, you know there are plenty of confusing and uncertain findings on its effects and efficacy—good and bad. Let’s look at some research around medical marijuana, including CBD and THC, to try to make sense of it.

What is medical marijuana?

The term medical marijuana refers to the whole, unprocessed marijuana plant. The plant and its extracts can be used to treat diseases, illnesses, and other conditions like chronic pain.

What are cannabinoids?

Cannabinoids are the chemicals found in marijuana used most often to treat patients. There are over 100 cannabinoids in a marijuana plant. Your body actually produces its own cannabinoids it uses for regulating memory, thinking, pleasure, body movement, appetite, concentration, pain, and your five senses.

It’s important to note that the US Food and Drug Administration (FDA) hasn’t approved the marijuana plant as a medicine; however, they do recognize three FDA-approved medications containing cannabinoids in pill form.

Researchers are most interested in the two main cannabinoids found in marijuana: THC and CBD.

What is THC?

THC is the mind-altering cannabinoid that gives people a “high.” As a treatment, it increases appetite and reduces nausea, important for cancer sufferers and others who can’t hold food down. The THC cannabinoid is also effective at decreasing pain, reducing swelling and redness, and easing muscle control problems.

What is CBD?

CBD is the cannabinoid that doesn’t produce a “high” in people. People don’t use CBD for recreational use; it’s mainly used to reduce inflammation and pain, controlling seizures, and treating addictions and mental illness.

The National Institutes of Health, the Center for Medical Cannabis Research, the National Center for Complementary and Integrative Health, and many more organizations continue to fund researchers exploring the potential uses for THC and CBD for medical treatment.

What cannabinoids are FDA-approved?

Per the National Center for Complementary and Integrative Health, the FDA has approved the following:

“In 2018, the agency approved Epidiolex (cannabidiol or CBD) oral solution for the treatment of seizures associated with two rare, severe forms of epilepsy. This drug is derived from marijuana. The FDA has also approved the synthetic cannabinoids dronabinol and nabilone to treat nausea and vomiting associated with cancer chemotherapy in people who have already taken other medicines to treat these symptoms without good results. Dronabinol is also approved to treat loss of appetite and weight loss in people with AIDS. Dronabinol contains synthetic delta-9-tetrahydrocannabinol (THC), a component of marijuana, and nabilone contains a synthetic substance with a similar chemical structure. In 2016, the FDA approved Syndros, a liquid form of dronabinol.”

Research papers supporting medical marijuana use

As CBD and THC gain traction in treating certain diseases, illnesses, and conditions, research is picking up. Here are a few of the research papers published on the effectiveness of cannabis as a medical treatment.

  • Association Between US State Medical Cannabis Laws and Opioid Prescribing in the Medicare Part D Population. This research looked at Medicare Part D prescriptions for opioids and found that filled prescriptions decreased in states with legalized medical marijuana. A similar study of Medicare Part D population found lower opioid prescribing rates in states with both legalized medical marijuana and adult recreational use.
  • Marijuana Legalization linked to Reduction in Prescription Opioid Overdoses. Two studies, both funded by the National Institute on Drug Abuse, found an adverse link between marijuana legalization and prescription opioids. One study found in states where marijuana use is legal, overdose deaths from opioid pain relievers decreased and continued to decrease each year after legalizing marijuana. The other study found patients having access to medical marijuana dispensaries had fewer opioid prescriptions, lower use of prescription opioid use, lower admissions for treatment of prescription opioid use disorders, and a reduction in opioid overdoses.
  • CBD Enhances the Anti-cancer Effects of Radiation. A research study using animals found that purified extracts of THC and CBD used to treat certain cancers in mice can slow the growth of cancer cells and kill or reduce the size of others. For example, purified extracts from the whole marijuana plant slows the growth of cancer cells involved in one of the most serious types of brain tumors. And when used with radiation, THC and CBD extracts increased its cancer-killing effects.

On the other hand, several research studies have shown adverse effects of marijuana on mental health such as:

  • Marijuana Use Linked to Psychiatric Disorders. Several studies show an increase in certain psychiatric disorders like depression, schizophrenia, anxiety, and substance use disorders for those using marijuana. However, these studies don’t point to marijuana causing these conditions; they just show a link. The strongest link is between people using marijuana who have pre-existing genetic risk factors for psychiatric disorders.
  • AKT1 Gene Carriers Using Marijuana at Risk of Developing Psychosis. Some adolescents carrying the AKT1 gene are identified with a genetic vulnerability to psychosis developed later in life. This gene manages an enzyme that triggers the neurotransmitter dopamine, which when altered can lead to schizophrenia.
  • European Study Links High Potency Marijuana to Psychosis. A major study of London, Amsterdam, 9 other major European cities, and Brazil found a link between high potency marijuana strains containing over 10% THC and an increased rate of psychosis. They found people who used high potency cannabis on a daily basis were 5 times more likely to be diagnosed with a new or first episode of psychosis compared to those who never used marijuana. Others in the medical field were quick to point out it could be “reverse causation,” meaning that people with psychosis are more likely to use marijuana than those without the mental health condition.

It’s important to note the many critics of the theory that weed use contributes to a higher risk of psychosis. They counter with the fact that while more people are using marijuana around the world today, the rates of psychosis haven’t increased. These studies don’t prove causality. In fact, many factors influence whether and how mental health disorders occur. Both genetics and environmental factors play a major role in the risk of mental disorders, much more than marijuana use.

There have also been studies showing that chronic marijuana use may have serious effects on the brain, much like those caused by addiction. In studies, some people expressed withdrawal symptoms when not using marijuana like mood swings, irritability, decreased appetite, restlessness, and sleeping problems. Researchers chalk it up to an increase in THC potency over the past few decades which leads to users needing more weed to get the same effect.

A study in New Zealand found that teenagers who started smoking marijuana heavily and continued into their adult years had an 8 point drop in IQ between the ages of 13 and 38. Even when they quit later in life, they didn’t regain those lost IQ abilities. But individuals who started smoking pot as adults showed no decline in IQ.

On the other hand, a study of twins looked at both twins who used marijuana and showed a significant decline in IQ between teen years and adulthood. However, the same study showed that when one twin used marijuana and the other twin didn’t, there was no predictable difference in IQ between their teen years and early adulthood. This points to something other than marijuana as responsible for their IQ decline, such as genetics or family environment.

Ongoing preclinical and clinical medical marijuana trials

Several ongoing cannabinoid clinical studies are looking at how the marijuana plant and its extracts can treat symptoms of the following illnesses and conditions:

  • Immune system disorders and diseases such as HIV/AIDS and multiple sclerosis
  • Inflammation and pain
  • Seizures caused by epilepsy and other disorders
  • Substance abuse disorders
  • Mental health disorders

For instance, researchers are currently studying:

Research doesn’t support marijuana as a “gateway drug”

Whether it’s a “gateway drug” or not depends on which research studies you read. For example, animal research shows that when they’re exposed early to THC, it changes the way their brains respond to other drugs. For example, if a rodent is repeatedly exposed to THC when young, it responds later to other addictive substances like morphine or nicotine.

However, the majority of people who use medical or recreational marijuana don’t go on to “hard” drugs. In fact, your environment and biological factors like genetics play a bigger role in your risk of drug use and addiction.

Why we need further research

The cannabinoid research performed to date hasn’t identified causal links, nor have researchers studied large populations for more reliable results. We need further research to determine the long-term effects of both medical marijuana and recreational use.

Much like alcohol and tobacco, marijuana has mood-altering effects that people enjoy. But the fact that so many people find relief from serious medical conditions, diseases, and disorders can’t be ignored. These same medical issues that others take prescription drugs for are now well-recognized as responding to the effects of medical marijuana use. This is why 33 states in the US have legalized the use of medical marijuana.

Clearly, we need more clinical evidence; everyone agrees. But since the US federal government still classifies marijuana or cannabis as a Schedule I drug, no one will invest hundreds of thousands or millions of dollars in large-scale clinical trials. Nor could they get trials approved by the federal government easily even though it has great potential for legitimate medical treatments.

For now, the medical marijuana and cannabis industry must rely on research conducted in other countries. Canada and Israel are leading the world in studying the efficacy and safety of medical marijuana. In fact, you can find many published studies on its benefit in treating epileptic seizures, multiple sclerosis, chemotherapy-induced nausea, and chronic pain of all types. Compared to the current opioid crisis, it makes sense that the federal government turn its attention to marijuana or cannabis as a potential alternative. We need to calculate the risks and the benefits and make informed decisions about what’s best for the population.

There may be hope on the horizon. In the government’s Fiscal Year 2020 budget, funding for the National Center for Complementary and Integrative Health is cut by about $20 million. But this isn’t stopping the center from reporting it will “support research on the diverse components of cannabis to explore if the pain-relieving properties can be separated from the psychoactive properties and to further characterize those components that may reduce pain.”

In an additional federal health agency push, the Agency for Healthcare Research and Quality is soliciting public input on marijuana as an alternative or supplement to using opioid painkillers.

Medical marijuana is now accessible in 33 states and the nation’s capital. Recreational use is now legal for adults over 21 in 10 states. As the cannabis industry rapidly grows and matures, like any grassroots effort started at the individual state level, the federal government will eventually succumb to the will of the people and decriminalize both medical marijuana and recreational use.

If you’d like to see where all 50 states stand in legalizing marijuana, click here for an interactive map. It details the laws in each state, and you’ll also find a table with legal status on a state-by-state basis.

Christopher Wright

Meet Christopher Wright, aka Blue, successful radio host and creator of Cannabis Talk 101. As well as CEO of Cannabis Talk Network. For over a decade now, Chris has had his hands in all faucets of the Cannabis Industry. From medicinal marijuana dispensaries and cultivations to controversial cannabis activism, Chris is a pioneer for the cannabis movement.