hand of researcher picking up a cannabis bud from a glass container

The science of cannabis, a work in progress

Cannabis touches everything from public policy to molecular biology to psychiatry, and there are risks and benefits to its use. However, whether you are currently for or against legalized cannabis use, you’re surely short on information. 

“Cannabis is a pharmacologically complex plant, with constituents that have the potential for producing both medical benefit and abuse,” says Margaret Haney, PhD, professor of neurobiology in psychiatry at Columbia University Vagelos College of Physicians and Surgeons and director of Columbia’s Cannabis Research Laboratory. She is one of only a handful of scientists who directly test the effects of cannabis on people and study its effects. “It's the most polarizing drug I've ever studied. It's even polarizing among scientists.” 

Margaret Haney, PhD, Columbia University Irving Medical Center

Margaret Haney

Haney believes the plant and its constituents have therapeutic potential but is concerned there is not enough scientific data to guide clinicians, politicians, voters, or others on how to really evaluate cannabis use. “You do not have to be anti-cannabis to want data,” she says.   

Cannabis has rarely undergone randomized, placebo-controlled evidence testing, the process required of every other prescribed medication. That’s mainly because the drug is illegal on the federal level, which makes it difficult to study. But with politicians and voters, rather than evidence, deciding what is medicine, cannabis can be deemed efficacious to treat anxiety and migraines in one state (e.g., New Jersey) but not another (e.g., New York). “Imagine if that were the case for antibiotics or antidepressants,” says Haney. 

Conflating the two aspects of cannabis legislation—recreational and medical—is a disservice to everyone, she says. “People need to think clearly about recreational and medical use of cannabis as separate issues. Let’s decide as a country about recreational use, but voters should not decide what’s a medication.” 

Is cannabis good or bad?  

It's both. 

“Cannabis is an old drug with new science,” says Haney, noting that the FDA has approved certain cannabinoids to treat anorexia, nausea, and vomiting in AIDS and cancer patients and to prevent seizures in some children with severe epilepsy.  

Current potency is an important issue. In the 1970s, when daily cannabis use was at its peak among high school students, the average potency of the flower was 1% to 4% THC. In 2014 it was 12% to 19%. Today you can buy concentrates that are 80% to 90%. “It’s really a whole different can of worms,” says Haney.  

For every claim that cannabis, including CBD, can cure cancer or diabetes, help someone lose weight, or calm pets is the issue of how much to take (dosage) and in what form (tinctures, pills, smoking, vaping, lotions). Again, asks Haney, how is the public to evaluate the essential principles of pharmacology and drug development?  

What’s actually inside cannabis products on the market is another unknown. Anything that reportedly has CBD in it, for example, may or may not include CBD. 

“I'm not throwing the baby out with the bath water,” says Haney. “I really do want to understand the therapeutic potential of CBD and THC and all the other cannabinoids. But we need randomized control trials, using a safely manufactured product of known composition.” 

Current cannabis research 

Female scientist examining cannabis sample in middle of green farm

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Cannabis studies are almost impossible to do. Even though cannabis is legal in many states for recreational or medical use, state laws do not allow scientists to conduct studies of cannabis. The FDA only permits scientists to study cannabis products with precise information about manufacturing. Cannabis dispensaries and companies do not have the information the FDA needs to allow scientists to test cannabis products.  

“We’re so woefully behind in determining what might be useful. One million studies need to be done,” says Haney. Currently, she and her colleagues are testing different types of cannabis to see how they compare in terms of relieving pain and producing intoxication. Are they effective? Do they stay effective over time? Do people who start using cannabis as a medicine develop a cannabis use disorder? 

Haney and her team are also studying the interaction between nicotine and THC. “Every drug of abuse [drug taken for nonmedical reasons] is associated with increased use of nicotine,” says Haney. How do the two interact? What changes if someone quits smoking cigarettes?  

“It’s a very exciting time to be studying cannabis and cannabinoids. In the past 20 years there have been marked advances in our understanding of endocannabinoids [the body’s THC-like chemicals] at the synaptic level, their role in neural circuits, and the impact of cannabis and its constituents. But there’s so much more to learn.” 


Margaret Haney, PhD, is professor of neurobiology in the Department of Psychiatry and director of the Cannabis Research Laboratory at Columbia University Vagelos College of Physicians and Surgeons. 

Cannabis | Columbia University Department of Psychiatry