Science and policy are often in tension with one another, but in the case of cannabis, as medicinal or recreational marijuana, science seems to be playing catch-up.
“Cannabis was scheduled [made illegal] in the absence of science,” and now is being legalized in some areas, still in the near-absence of science, said J. Michael Bostwick, a practicing psychiatrist and a senior associate dean at Mayo Medical School. In 1970, when Congress classified cannabis as Schedule 1 (“drugs with no currently accepted medical use and a high potential for abuse”), scientists did not know which neuronal receptors it activated or what exactly in the substance was causing which effects.
More than four decades later (and 5,000 years since people first started using it as pain reliever), we still don’t know much more of the botanical substance’s potential as a medicine, because its Schedule 1 status means US researchers have to jump through hoops at several different agencies to get access to the legal federal supply. That’s just the start, science-wise: As with any plant, cannabis varies widely in quality, strength, and in what other compounds are bound within the plant, so research—and comparing previous studies in the US and elsewhere—can be tricky.
“Since 1970, we’ve really learned to understand this endocannabinoid system,” the nervous system receptor that cannabis links to, Bostwick said. The system influences pain and stress responses, memory, appetite, metabolism, immune function, neurogenesis, and more. If we could tease out the effects of compounds in cannabis (and dose ranges), we might find new treatments for many diseases, “if we could actually do the research,” he said during a forum at the American Association for the Advancement of Science (AAAS) in Washington, DC, on Wednesday. [See event video, below.]
Meanwhile, we are learning more specifics about cannabis’s harms, especially to teenagers, said Nora Volkow, director of the National Institute on Drug Abuse (NIDA) and a member of the Dana Alliance for Brain Initiatives. Adolescence is a “sensitive period,” when the brain is making many rapid changes. “At age 17, your risk to become addicted is much, much higher” than in later adulthood, Volkow said, describing data from the long-term Dunedin studies in New Zealand. Additionally, “the more the period of consumption [in adolescence], the greater the decrease in IQ points” [see study].
The Dunedin study and work in Europe has found links between chronic consumption and the onset of psychoses including schizophrenia, she said. “I wouldn’t say marijuana by itself could cause psychosis,” Volkow said, but it could trigger an episode that might not otherwise have been triggered, “and it could lead people to develop psychosis that might never have otherwise emerged.” [See Cerebrum 2015 essay by Sir Robin Murray for a European perspective.]
To learn more, the US National Institute of Health has started its own prospective study, planning to follow 10,000 healthy children ages 9-10 for 10 years, measuring environment, social, genetic, and other factors and seeing how they affect brain and cognitive development and the young people’s life trajectory. “So if you ask me in 10 years, we will have many, many more answers,” Volkow said.
Some states and jurisdictions, such as the District of Columbia, aren’t waiting. David Grasso, a member the DC city council, described that city’s path to legalizing cannabis for adults. “The reality is no one has all the science… but as we moved forward with medical marijuana we did it with a lot of caution.”
“For us it was not a question of the science of marijuana, but the science of incarceration,” Grasso said. “I certainly don’t encourage people to smoke or use marijuana, but I do know that when we send people to jail [for nonviolent offenses] … we were hurting more people than we were helping.”
This puts people in DC, as well as two-dozen states, in a strange bind: Something increasingly legal at home is illegal across a state line and to the federal agent next door. Doctors, who are licensed by their state but given permission to prescribe medicine by the federal government, are also in a bind, Bostwick said. His right to speak about marijuana as medicine to his patients is protected under Free Speech rights, not under his license (because Schedule 1 drugs have “no currently accepted medical use”).
“The states have gone rogue on this,” he said, which might push the federal system to act. It appears “there’s a shaky détente at the federal level,” with agents mostly going after illegal trafficking, not small-scale users. Meanwhile, there is no consistency state to state on how to certify a patient needs medical marijuana, or how to dispense it, or how to ensure it is processed properly. “It’s very odd to have a patient traveling to one state to get medical marijuana, and then [coming home and] asking me if it is harming her,” Bostwick said, not to mention her telling him how she’s hiding it in the toilet of her RV so she won’t get caught crossing state lines.
A lack of consistent regulation hasn’t stopped entrepreneurs, though. “There are literally more dispensers of marijuana than there are Starbucks” in Colorado, which has legalized marijuana for both medical and recreational use, said Volkow.
The legal status of substances such as alcohol and tobacco has made them widely available and socially acceptable, even though some percentage of people are harmed (through addiction and accidental injury). While an aggressive campaign against cigarette smoking has led to a steep drop in the number of high-schoolers who smoke tobacco, the number who smoke pot has stayed steady for the past five years. People start to think: If it’s legal, it must be safe, right?
“For the past five years, we have seen that smoking cannabis is more common than smoking cigarettes,” Volkow said. “I would say that marijuana is much more dangerous for a teenager than nicotine,” she said, because the brain changes during adolescence will last the rest of a person’s life, while people can pollute their lungs for decades before the damage starts to affect their her daily routine. “Hopefully we have learned from tobacco and we can offset the adverse effects” of legalizing cannabis, she said, by explaining risks.
Grasso warned against over-strident messaging, though: “I think there’s a difference between scaring our youth and educating them. When I was growing up, the War on Drugs was raging… When you thought that prohibition was controlling it? If you grew up in Petworth [neighborhood] like me, it did not work.”
This event was part of the Neuroscience and Society series, supported by AAAS and the Dana Foundation. Previous sessions include Creativity, Genius, and the Brain (story, video); Mental Illness Across the Ages (story, video); The Neuroscience of Infant Development (story, video); Stress and the Brain (story, video); and The Science of Sleep (story, video). The next session, on cognition and aging will be Wednesday, June 15.
– Nicky Penttila