The Science Behind Medical Cannabis: Separating Research from Hype

The debate around the pros and cons of medical cannabis has changed a lot since Colorado became the first state to legalize medical marijuana in 2000. For those who remember when they could only buy marijuana off the street, the push towards legalization has brought great relief and less stigma, especially for those who primarily use it for pain relief. But more research and studies are still necessary to determine the risks and benefits of cannabis for patients.

Whether you're a healthcare professional considering cannabis as a treatment option or simply want to understand the science behind the headlines, this guide separates fact from fiction about medical cannabis efficacy, safety, and legal parameters

From both a medical and legal perspective, it's important to distinguish the different terms that often get misconstrued when discussing medical cannabis:

• Cannabis refers to the dried leaves, flowers, stems, and seeds of the cannabis plant. The plant has many different chemical compounds.
• THC is the primary psychoactive compound in cannabis, responsible for the “high” associated with marijuana.
• CBD is non-psychoactive, meaning it doesn’t produce a “high.” It interacts with the ECS indirectly, modulating CB1 and CB2 receptor activity without binding directly to them, making it a preferred option for those who want to feel calm and relaxed without getting high.
• CBN forms as THC ages and oxidizes. Its weak affinity for CB1 receptors results in minimal psychoactive effects. CBN’s interaction with the ECS suggests potential for promoting relaxation and sleep.
• Hemp is a variety of the cannabis sativa plant explicitly grown for industrial and commercial uses, such as making paper, textiles, and food.

From laboratory to clinic: Cannabis research milestones

In 1964, Israeli chemist Raphael Mechoulam, along with his colleague Yechiel Gaoni, first isolated and identified the structures of THC (delta-9-tetrahydrocannabinol), the psychoactive compound in cannabis, and CBD (cannabidiol). Building upon that, scientists at the St. Louis University Medical School determined in 1988 that a rat’s brain has receptor sites—specialized protein molecules embedded in cell membranes—that are activated by THC. Initially identified by Professor Allyn Howlett and her graduate student William Devane, and cloned two years later, this cannabinoid receptor, dubbed “CB1,” turned out to be far more abundant in the mammalian brain than any other G-protein-coupled receptor (GPCR).¹

CB1 receptors regulate various bodily functions and are activated by endocannabinoids, which are the body's own cannabis-like molecules. CB1 receptors are most abundant in the brain; activating them can suppress the release of excitatory and inhibitory neurotransmitters, leading to effects such as euphoria, altered perception, reduced pain, and changes in motor control.  

Our body’s endocannabinoid system (ECS) is critical for almost every aspect of our moment-to-moment functioning. The ECS regulates and controls many of our vital bodily functions, such as learning and memory, emotional processing, mood, sleep, temperature control, pain control, inflammatory and immune responses, and eating.²

“The thinking is that when ingested or inhaled, THC or CBD binds to specific receptors on the brain and nerve cells, which slows pain impulses and eases discomfort. They also may provide anti-inflammatory effects, which may help reduce pain,” says Staci Gruber, director of the Cognitive and Clinical Neuroimaging Core and the Marijuana Investigations for Neuroscientific Discovery (MIND) program at Harvard-affiliated McLean Hospital.³

Because the THC in medical cannabis can activate or stimulate these brain receptors, it’s imperative to consider its effect on various parts of the brain, including the cerebellum and basal ganglia (movement, motor control), the cerebral cortex (higher cognitive function), the hypothalamus (appetite), the medulla (nausea), the hippocampus (memory and learning), and the spinal cord (pain, peripheral sensation).  

What conditions respond to cannabis treatment?

Over the past two decades, medical cannabis has been proven to alleviate a variety of ailments and disorders. One of its most common uses is to treat both chronic and mild pain. People use medical cannabis for arthritis, back or neck pain, joint pain, reducing inflammation, and even to relieve migraines and headaches.

In recent years, the study of medical cannabis has led to its usage for more serious disorders. In 2018, the FDA approved Epidiolex®, the first prescription drug derived from cannabis plants, to treat seizures associated with specific, severe forms of epilepsy. This FDA approval represented a significant shift—providing clinicians with an evidence-based, regulated option for previously treatment-resistant conditions. It also opened the door to exploring potential therapeutic uses of medical cannabis on many other serious conditions, including multiple sclerosis, Alzheimer’s, Parkinson’s, and more.

For years, many cancer patients have also relied on medical cannabis to help treat side effects that come with chemotherapy. In 1985, the synthetic THC drug Marinol® was approved by the FDA primarily for chemotherapy-induced nausea and vomiting, which some believe helped start the push to legalize cannabis on a broader scale. Medical cannabis has also been used to help stimulate appetite in AIDS patients who have become anorexic or elderly patients suffering from wasting syndrome.

Despite these benefits, one of the biggest concerns is whether cannabis will interfere with a patient’s cancer treatment or make immunotherapy treatments less effective. It can be hazardous if a patient doesn’t reveal to their doctor that they’re using non-medical cannabis for pain relief. While many doctors are embracing this treatment, others remain hesitant to incorporate medical cannabis due to a lack of research on its long-term effects and safety.

The benefits of medical cannabis are not just physical. Many people use it to treat anxiety, depression, and PTSD. But for more serious mental health conditions such as schizophrenia, bipolar disorder, or severe psychotic disorders, more research is needed, especially about using medical cannabis in combination with SSRIs and other prescription medications for these disorders.

Medical cannabis has been around long enough to prove many medical benefits. Still, the amount of research and studies needed to fully understand its efficacy will take many more years to complete. Always see a doctor who is highly knowledgeable about medical cannabis and license to prescribe it if you’re going to pursue this type of treatment.

What patients need to know about medical cannabis safety

Every medication carries risks, and medical cannabis is no exception. Understanding these risks helps clinicians make informed treatment decisions. One common misconception is that medical cannabis is harmless because it’s natural and plant-derived, but that is not entirely true. The effects of using medical cannabis depend on the type of strain, the dosage level, the amount of cannabis being ingested daily, and a patient’s physical and psychological makeup. It also depends on the patient’s lifestyle and any other medications or drugs they are taking.

Dr. Randall Tackett, adjunct MS in Clinical Psychopharmacology faculty at Alliant University and a professor and associate department head at the University of Georgia College of Pharmacy, provides this pharmacological perspective: “Cannabinoids have medical value, they do. Are they superior to existing medications? Not always. And since they are natural substances, many people say they have no side effects. That is not correct. Every drug has side effects, and not all cannabinoids have the same effects. It depends on what is in each preparation. Just because it comes from state-approved sources doesn't necessarily mean it's a consistent amount of cannabinoids.”⁴

Because cannabis affects CB1 receptors in the brain, every patient’s response to it is unique. While it’s used to help calm spasms and seizures in some patients, in others it can cause difficulty with movement and walking. Many healthcare professionals are also concerned about people under 25 using it in excess because of its effects on cognition, which can impact receptors in the cerebral cortex.

The delivery method is also an important consideration. Medical cannabis is primarily delivered in the form of edibles or gummies. Those who vape or smoke cannabis open themselves up to other problems, such as lung damage or the risk of other impurities that may be present in vape pens. This is why regulations on how cannabis is grown and cultivated are important; until it becomes legal on a federal level, however, these will vary from state to state.

“Ultimately, someone has to make a decision: what is the benefit versus the harm?” asks Dr. Tackett. “If there's a hypersensitivity to it, if there is a history—either personally or family history—of psychosis or schizophrenia, cannabis use disorder, or any other active substance use disorder, it's not recommended. Pregnant or breastfeeding, we know these drugs will get across the milk and get into the fetus also. And then if there's any significant cardiovascular or pulmonary disease, that's sort of the general contraindications for this use of cannabis.”⁵

Cannabis use disorder: Myths and realities

Let's address a common misconception: While cannabis has a lower addiction potential than many substances, cannabis use disorder is a real clinical concern. “We know that marijuana acts in the Mesolimbic Reward Center,” says Dr. Tackett, “so that is one of the reasons that we get the euphoria, and it could also contribute to the potential addiction aspects of marijuana.”⁶

Even if there is a risk of addiction or dependence, some people still argue that it’s a safer option, stating that there has been no known lethal overdose reported with THC and that, unlike alcohol, no one has killed themselves by driving after ingesting too much medical cannabis, but there have been exceptions.

In March 2014, the Colorado Department of Public Health and Environment (CDPHE) learned of the death of a 19-year-old man after he consumed an edible marijuana product. A police report indicated the man initially ate only a single piece of his cookie, as directed by the salesclerk. Approximately 30–60 minutes later, not feeling any effects, he consumed the remainder of the cookie. During the next two hours, he reportedly exhibited erratic speech and hostile behaviors and eventually jumped off a fourth-floor balcony and died from trauma. The autopsy, performed 29 hours after the time of death, found marijuana intoxication as a chief contributing factor.⁷

While not fatal, in another case, a 52-year-old man with a fast-growing, malignant cancerous brain tumor (anaplastic astrocytoma) was admitted to the emergency room with acute delirium after ingesting a liquid marijuana formulation (not prescribed by a physician) two days earlier, to stimulate his appetite. The packaging described approximately 500 mg of 65.9% THC in a 1-ml syringe, of which two-thirds had been administered.⁸

While it appears to be rare, the medical profession cannot rule out addiction to cannabis or claim that it is 100% safe.

Navigating federal and state cannabis laws

For prescribers, understanding cannabis law isn't optional—it's essential for protecting both your practice and your patients. As more states legalize medical and/or recreational cannabis, new products are being developed every year: gummies, pain relief gels, beverages, even pet foods tout the positive effects of THC and CBD. This was partially accelerated by the Hemp Farming Act of 2018, which removed hemp (defined as cannabis with less than 0.3% THC) from the federal Controlled Substances Act. This legalized hemp’s cultivation, processing, and sale as an agricultural commodity, making it eligible for federal crop insurance, grants, and banking services.

However, this bill should not be interpreted as a federal legalization of cannabis, which is still considered a Schedule 1 drug under the Controlled Substances Act. Schedule 1 drugs are illegal at the federal level, defined as having a high potential for abuse and no accepted medical use. This federal law is not typically enforced in states that have legalized medical or recreational use, though the DEA is constantly reviewing the parameters.

For anyone prescribing medical cannabis, it’s crucial to know the laws where you practice, since they vary by state. This is where legal complications and confusion can arise, as many patients believe that their medical cannabis prescription is acceptable wherever they travel in the United States. However, their prescription is only valid in their state of residence. With air, auto, and train travel falling under federal jurisdiction, traveling with marijuana—even with a prescription—is prohibited because you are crossing state lines. For those who use CBD, there is also still a risk of failing a drug test; a medical marijuana card does not always translate to a “get out of jail free” card.

Without federal legalization, there are also no FDA regulations on most products, except for the FDA-approved synthetic THC medications: Marinol®, Syndros®, Cesamet®, and Epidiolex®, whose active ingredient is CBD. This means buying products at dispensaries requires a great deal of trust in reputable companies to ensure these products are safe and that their dosage labels are correct.

For states that have only legalized medical cannabis and not recreational cannabis, a prescriber usually must pass an exam on medical marijuana and verify that a patient has a qualifying condition approved by the state before writing a prescription. In some cases, they must also prove that conventional therapy or medical treatment has failed before they can prescribe medical cannabis. The patient then must show proof of state residency, purchase a medical marijuana card, and be entered into a registry before they can receive the prescription.

Alliant University: A pioneer in prescriptive authority

Although cannabis has existed for thousands of years, the journey of cannabis from illegal substance to medical use to recreational use has been decades in the making, and medical cannabis is still in its infancy. There is substantial evidence that medical cannabis provides great benefits to patients in a variety of ways, from mental stress relief to pain management to controlling epileptic seizures. That said, it remains essential for healthcare professionals to understand both the science and regulations behind medical cannabis for effective patient education and informed treatment decisions.

This is precisely why Alliant University developed its online MS in Clinical Psychopharmacology program—to bridge the gap between psychology and pharmacology in an era of expanding treatment options. Becoming more knowledgeable about the potential benefits of medical cannabis is crucial if you are a licensed psychologist looking to expand your practice in psychopharmacology. If you're curious to hear more of Dr. Randall Tackett's expertise in pharmacology, toxicology, and substance abuse, check out his medical cannabis-focused episode of Alliant's Psychopharmacology Today podcast here.

Ready to earn your degree from a pioneer in the prescriptive authority movement? Contact an admissions counselor at Alliant University today.

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Sources

1. Lee, M.A., “Endocannabinoid Discovery Timeline 25 years of groundbreaking research — an annotated history.” Project CBD, July 1, 2020, https://projectcbd.org/science/endocannabinoid-research-timeline/
2. Grinspoon, P., MD. “The endocannabinoid system: Essential and mysterious,” Harvard Health Publishing, Harvard Medical School, August 11, 2021, https://www.health.harvard.edu/blog/the-endocannabinoid-system-essential-and-mysterious-202108112569
3. Solan, M. “Can cannabis help relieve pain?”, Harvard Health Publishing, Harvard Medical School, April 1, 2023, https://www.health.harvard.edu/pain/can-cannabis-help-relieve-pain
4. Tackett, R. Dr. (Guest). (2025, July 24). “Medical Cannabis: Separating Science from Hype” (No. 3) [Audio podcast episode]. Psychopharmacology Today. Alliant University. https://www.alliant.edu/podcasts/psychopharmacology-today
5. Tackett, “Medical Cannabis: Separating”
6. Tackett, “Medical Cannabis: Separating”
7. Hancock-Allen, J. B., Barker, L., VanDyke, M., Holmes, D. B., “Notes from the Field: Death Following Ingestion of an Edible Marijuana Product — Colorado, March 2014”, Centers for Disease Control and Prevention, July 24, 2015, https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6428a6.htm
8. Author unknown, “Medical Marijuana Miscalculation”, New England Journal of Medicine, Vol. 381, No. 11, September 11, 2019, https://www.nejm.org/doi/full/10.1056/NEJMc1907013