Long-awaited changes in drug policy could bring scientists one step closer to understanding the harms and benefits of marijuana, the most commonly used federally illegal substance.
On Thursday President Donald Trump signed an executive order who moved to reclassify cannabis from a Schedule I substance to a Schedule III substance, following regulatory changes first proposed during the Biden administration.
“For decades, federal drug control policies have ignored the medical uses of marijuana,” the order states. “This oversight has limited the ability of scientists and manufacturers to complete the necessary safety and effectiveness studies to inform physicians and patients.”
Although the reclassification is intended to support medical marijuana research and will not legalize cannabis At the federal level, the move comes at a time when use in the United States is at a high level. Gallup data An estimated 15% of adults will smoke marijuana between 2023 and 2024, up from 7% in 2013.
The survey, which did not distinguish between medicinal and recreational use, found the highest use (19%) among young people aged 18 to 34, a group for which research has shown cannabis has devastating psychiatric effects. For example, a study published Tuesday in the journal Pediatrics found that using marijuana just once or twice a month was associated with emotional distress and poorer school performance among adolescents.
Medical marijuana is commonly prescribed to relieve chronic pain; control nausea and vomiting, often in people receiving chemotherapy for cancer; and stimulate appetite in people with certain medical conditions. It is unclear whether the cannabis deadline will impact funding for recreational marijuana research.
Scientists like Ziva Cooper hope the reclassification could revolutionize public health through more comprehensive research on marijuana.
“It is extremely difficult to study cannabis, also known as marijuana, for both potential side effects and therapeutic effects,” said Cooper, director of the UCLA Center for Cannabis and Cannabinoids. “The industry is evolving at a very fast pace and consumer behavior is evolving along with it.
“It's very difficult for us as scientists and people interested in public health to keep up with changes, in part because the research is complex.”
Schedule I is the most restrictive of the five categories of controlled substances recognized Drug Enforcement Administrationreserved for drugs with “no current medical use and a high potential for abuse,” including ecstasy, heroin, LSD and peyote. Schedule III drugs, which include ketamine, testosterone And anabolic steroidAccording to the agency, they have a “moderate or low potential for physical and psychological dependence.”
Even though she works in a cannabis-friendly state, Cooper said she faces the same research obstacles as her colleagues in states like Idaho, where marijuana use is not legal at all.
“Researchers can't test what's readily available on the market, they just ask basic questions about what's in the products that are available at the pharmacy that I can see outside my lab window, for example,” Cooper said. “This also means that there are certain restrictions on where we can obtain the cannabis we are researching on.”
The harms and benefits of marijuana require further study
Last year National Institutes of Health committed $75 million to therapeutic cannabinoid research, up from $70 million in 2023. In addition, $217 million went to cannabinoids, or cannabis compounds, and $53 million went to cannabidiol or CBDnon-psychoactive cannabinoid.
However, administrative bureaucracy means that cannabis research is often observational in nature compared with the rigorous clinical trials required for pharmaceutical research, said Dr. Brooke Worster, medical director of the master's program in medical cannabis science and business program at Thomas Jefferson University in Philadelphia. Their findings were mixed.
For example, a 2024 study published in the journal Current Alzheimer's Disease Research found that recreational cannabis use among adults aged 45 years and older was associated with a 96% lower risk of subjective cognitive decline compared with non-cannabis users. However, a 2025 study published in The JAMA Network is open found that among adults aged 22 to 36 years, heavy marijuana smokers had impairments working memory.
A study published this year in the journal Biomedicines found cannabinoids to be a “promising” alternative to opioids for the treatment of chronic pain, but pointed out the urgent need for large-scale randomized controlled trials. Meanwhile, a study published last year in The JAMA Network is open found that older adults with Medicare were more likely to see a doctor for cannabis use disorders from 2017 to 2022.
The reclassification will allow researchers to categorize and study specific marijuana formulations, Worster said. Now, even in states with medical marijuana programs, the quality and potency of cannabis products can vary widely from dispensary to dispensary.
“We can actively monitor immediate symptoms or levels of substances in the blood, as well as long-term effects,” she said. “Everything that you would want to do if you were studying a drug, everything that the federal government would otherwise require us to do to study a drug.”
Although marijuana may have some medical benefits for some people, Jonathan Caulkins, the H. Guyford Steve University Professor of Operations Research and Public Policy at Carnegie Mellon University in Pittsburgh, denies that administrative checkpoints prevent cannabis from treating diseases such as cancer or Alzheimer's disease.
“They are not limiting research to Canada, France or Israel,” Caulkins said. “I don't think we should imagine that the only reason cannabis hasn't become a miracle drug is because of any U.S. laws, because we're not the only country in the world that has a pharmaceutical industry and a research base.”
However, Worster said the changes bring new responsibilities to the medical community. inhalation products any concentration or composition is not safe for everyone.
“What remains to be figured out is how do we provide the right patient with the right medicine and the right guidance?” she said. “Existing products are often unregulated. There are real risks to mental health, to young people who use them too regularly, and of course to some cardiovascular effects We need to pay more attention to this.”
Cannabis policy to be reviewed after 55 years
regulatory obstacles Researchers were faced with a problem that arose more than half a century ago. During the Nixon administration, the Controlled Substances Act of 1970 made cannabis a Schedule I drug.
Almost 60 years later, much of marijuana's medical potential, or lack thereof, remains unknown. From a legal perspective, Worster said, “it's just a drug.”
Susan Ferguson, director of the Institute on Addiction, Drugs and Alcohol at the University of Washington School of Medicine, expects it will soon be easier for scientists to obtain licenses for cannabis research. Currently, she said, researchers can obtain a broad license to study any drug in Schedules II through V. Those who want to study a Schedule I drug must obtain a separate license for each substance.
“This involves extensive protocol writing,” she said. “It involves DEA agents coming out and inspecting the lab and telling me about the research and experimental plans. It gets very, very complicated.”
Moving marijuana, Ferguson said, would “open the floodgates” for clinical research. First, people may be more willing to participate in studies of Schedule III rather than Schedule I drugs.
Ferguson compared cannabis to alcohol And tobacco – the products are ordinary, but not harmless. Medical research is the reason why their harm is well known.
“We haven’t done any cannabis research,” Ferguson said. “Eventually it will be able to tell people what the risks are, what the benefits are, and just give people more information.”
