Your Brain on Drugs: Neuroscientists Narc on Legal Marijuana

That heady scent of open-air pot-smoking is just another sign of springtime come to D.C. nowadays. (Move over, cherry blossoms.) Wednesday near dusk I met an otherwise upstanding young guy on the sidewalk in leafy residential Northwest, waiting for a ride with a crackling joint in hand—not an unusual sight, but it was the eve of the “marijuana holiday,” I remembered: April 20, or 420, reportedly popularized by goofball friends of Grateful Dead bassist Phil Lesh.

The District legalized recreational and medical marijuana in 2015, but stodgy Congress is still blocking its recreational commercial sale—which means that girl who called her dealer from the Trader Joe’s line the other day might have been breaking the law. On Election Night, California, Massachusetts, Nevada, and Maine legalized recreational marijuana, joining Oregon and Alaska—and Washington state and Colorado, who’d blazed (get it?) the trail back in 2012. But even they’ve found no functional regulatory framework to manage the mind-altering herb’s non-criminal commercial distribution. And there’s no simple solution for its dangerous neuropsychological side-effects either, proven to disturb teenagers’ growing brains. (Like alcohol and cigarettes, recreational marijuana finds its way into the possession of the wily underaged.)

Disturbing your teenaged brain might sound like a great time to some. But it’s not quite as simple as feeding your head, as Grace Slick said, or opening the “doors of perception” the way they did in good old days. That’s because the concentration of tetrahydrocannabinol (aka THC, the drug’s main psychoactive ingredient) in today’s weed blows the doors off the leaf your papa rolled. Back in the 1960s and ’70s, marijuana had a relatively even distribution of THC and cannabinoid compounds—chemicals whose effects cancel each other out—and so the dangers to neurodevelopment were not nearly so grave in those days, Dr. Steven Laviolette explained to me.

To better understand the correlation between THC exposure and schizophrenia, Laviolette, a professor in the department of Anatomy and Cell Biology and Psychiatry at the University of Western Ontario’s medical school, studies the effects of THC on lab rats. In his lab, he exposes “the rat equivalent of the teenaged brain to chronic levels of THC”—the only way, pre-clinically, to control exactly how much of the chemical the brain received. He’s found that “exposure to high levels of THC during the adolescent period of brain development increased the likelihood of developing schizophrenia-related symptoms into adulthood.”

An adult brain exposed to the same amount of THC shows minor deficits in memory and cognition, he said—but “nothing comparable with the sorts of changes we see with adolescent exposure.” In Canada, where handsome young prime minister Justin Trudeau has made legalizing marijuana a high priority for the year, “the biggest concern really is exposing the teenaged brain to strains of marijuana that have really high levels of THC.” As it should be here in the U.S.

But, when asked whether he worried Canadian and American legalization efforts were risky and reckless, motivated by political fashion more than good legislative sense, Laviolette declined to go full narc with me. “It’s definitely moving ahead ahead of the science,” he allowed.

Indeed your garden-variety store-bought marijuana won’t likely be well-regulated. And it may not be accurately marked. Laviolette confirmed the potential discrepancy between real and reported THC levels by testing a strain purchased in Colorado: Its label read a lower THC count than he measured in the lab. “You can draw comparisons to the tobacco industry,” he said. “Once the tobacco industry realized that the addictive compound in cigarettes was nicotine, they started breeding the plants to have higher and higher levels of nicotine—so we’re sort of seeing a similar sort of market-driven increase in THC content.” And the mislabeling? It’s as much a product of imprecision as it a symptom of dangerously cynical salesmanship.

And conflating cannabinoid therapies for cancer patients and opioid addicts with the dried marijuana flower is another. “It’s not about medicine, it’s about economics,” Dr. Hoover Adger, Jr., a professor of pediatrics at the Johns Hopkins University School of Medicine, told me—noting that, “Medical marijuana is an oxymoron.” (You don’t pull the digitalis root out of the earth and give it to a heart patient to chew on, Dr. Adger added.)

“The fact that this is now being decided by ballot initiatives? That’s just contrary to everything that most of us know about medicine. Campaigns and public decisions by residents of 28 states to make medical and/or recreational marijuana legal ignore medical data on cognitive impairment, the likelihood of addiction and abuse, and the simple fact that “when you dump mood altering substances into the middle of a key formative period for young adults and adolescents, that’s a major problem.”

And Dr. Sion Kim Harris, pediatrics professor at Harvard and co-director of the Center for Adolescent Substance Abuse Research at Boston Children’s Hospital, would frame marijuana legalization as “Big Tobacco redux.” Massachusetts is in the midst of managing its recreational marijuana legalization rollout, thanks to a successful ballot measure last year. The likeness to big tobacco, Harris said, is obvious—”in terms of advertising and creating products that are very attractive for young people, even children, and the advertising that says ‘marijuana is harmless,’ ‘it’s natural,’ ‘the war on drugs hasn’t worked, and this is a social justice issue.’ They’re coming at this from all different angles.”

Meanwhile, “Those of us who are in pediatric health, the vast majority of us, in terms of who I know and my colleagues, are against legalization,” Dr. Harris said. Because of the teenage brain’s high neuroplasticity—its formative capacity to learn and grown, to stretch and adapt to stimuli—potential for addiction is at an all-time high, so to speak. Contrary to popular myth, addiction to marijuana is an increasingly common condition. Like any drug, Dr. Harris said, marijuana “activates the same circuitry in the brain that every single other addictive substance activates, and hijacks it.” Indeed, several of the cannabis studies compiled in a volume published this January by the National Academies of Science, Engineering, and Medicine monitor addicts’ withdrawal symptoms and record rates of cannabis dependence.

While April 20 is still a secular high holiday, a day that could lose its specialness in an era of unrestricted ganja, April 21 is a day to withdraw. Lighter and more manageable than those experienced by addicts to opiates or prescription sedatives like Xanax, weed withdrawal still brings the sort of symptoms that make some people want to smoke it in the first place. Irritability, sleeplessness—sort of like seasonal allergies. April is supposed to be the cruelest month after all.

This post originally appeared on Weekly Standard

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