You can now read 10 articles in a month for free on BostonGlobe.com. Read as much as you want anywhere and anytime for just 99¢.

The Boston Globe

Health & wellness

Science lacking on Obama’s pot claim

When President Obama declared in a recent New Yorker magazine interview that he doesn’t think pot “is more dangerous than alcohol,” he seemed to contradict his own administration’s policy that’s firmly against the legalization of marijuana. He also seemed to indicate that the pot smoking he did in his teens had no major health impact.

“I view it as a bad habit and a vice,” he told the New Yorker’s David Remnick, “not very different from the cigarettes that I smoked as a young person up through a big chunk of my adult life.”

Continue reading below

That’s a position a lot of teens take today, judging by the fact that more teenagers smoke pot than cigarettes, according to a 2012 survey from the federal Centers for Disease Control and Prevention.

But there’s a scarcity of research to determine just how risky it is to use marijuana purely for recreational purposes—which is legal in Colorado and will be soon in Washington.

“I don’t know if we have any definitive answers about cannabis use and its long-term health impact,” said Dr. Yasmin Hurd, a professor of psychiatry and neuroscience at the Icahn School of Medicine at Mount Sinai in New York. “It hasn’t been studied as much as cigarettes and alcohol.”

That’s partly because it’s illegal under federal law and considered by the US Drug Enforcement Administration to be a Schedule I dangerous drug; researchers need to apply for special approval to study it—especially in people.

Hurd and drug policy researchers distinguish the recreational use of the drug from its medicinal use, which also hasn’t been well studied but has anecdotally been shown to ease pain, nausea and other symptoms in those with certain chronic health conditions. Marijuana dispensed for medical purposes was legalized last November in Massachusetts.

Even if smoking pot carries the same health risks as alcohol, as Obama claims, that doesn’t bring much comfort to Dr. Timothy Naimi, a substance abuse policy researcher at Boston Medical Center. “Excessive alcohol use is the third leading cause of preventable deaths in the U.S.,” he said, “and binge drinking in teens is associated with injuries, fights, and worse school performance.”

Regular marijuana use comes with a different set of problems: One in six adolescents who uses pot regularly will become addicted, according to Susan Weiss, associate director for scientific affairs at the National Institute on Drug Abuse. “Our studies indicate that 6.5 percent of teens use marijuana daily or almost daily,” she added, “and that’s likely an underestimate.”

She and other public health officials are most concerned about marijuana’s health effects on teens who use it recreationally because that’s a crucial time of brain development. A 2012 Duke University study found that IQ scores dropped in teens who started smoking pot and continued into adulthood, while other research suggests the habit may interfere with memory and lead to an impairment in assessing dangerous risks.

And a new animal study conducted by Hurd and her colleagues suggests that marijuana use in teens could impact the programming of certain genes that increase drug addiction tendencies in offspring conceived years later.

The study, published Wednesday in the journal Neuropsychopharmacology, was conducted in rats who were exposed to THC—the active ingredient in marijuana—during their adolescence.

“They had the equivalent of a joint every few days and then stopped in early adulthood before giving birth to offspring,” Hurd said. “Their offspring were more likely to seek out heroin that was offered to them and to exhibit withdrawal symptoms when not given the drug compared to those born to rats given a placebo.” All of the baby rats were raised by non-biological parents not exposed to any THC.

“It’s a very disturbing and intriguing finding,” Weiss said. “We’ve all been conscious of the fact that prenatal exposure to certain drugs and toxins can have long term consequences, but now we’re seeing that what we do as teens -- a vulnerable time of brain development -- may have an impact on our future offspring.”

More research is needed to determine whether this finding applies to humans, but Weiss said legalization of marijuana use in some states has “added an amount of urgency” in terms of the institute’s priority to learn more about pot’s health effects.

While Obama shouldn’t be too worried about his daughters drifting towards hard drugs because of his past “bad habit,” he’s certainly smart to discourage them from trying weed. “I’ve told my daughters I think it’s a bad idea, a waste of time, not very healthy,” he said in the New Yorker interview.

He also argued that legalizing marijuana would present some “difficult line-drawing issues” like people arguing that small calibrated doses of meth and cocaine should also be legalized if science can show they’re no more harmful than vodka.

The slippery slope argument might be a valid one against pot legalization, but here’s an even more compelling reason: “With any substance—alcohol, tobacco—availability in the general society means more availability to youth,” Naimi said, even if there are age restrictions that prohibit them from purchasing it.

Perhaps more troubling: The potency of pot has increased over the past few decades with a THC content that’s now about 15 percent in products seized during raids, according to Weiss, instead of 3 to 4 percent in the past. “We know that people exposed to higher levels can get more of the nastier effects like paranoia, increased heart rate, and psychosis,” she added.

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.

You have reached the limit of 10 free articles in a month

Stay informed with unlimited access to Boston’s trusted news source.

  • High-quality journalism from the region’s largest newsroom
  • Convenient access across all of your devices
  • Today’s Headlines daily newsletter
  • Subscriber-only access to exclusive offers, events, contests, eBooks, and more
  • Less than 25¢ a week