Marijuana: the Gateway Drug (to Nicotine)

New research suggests that smoking pot promotes an even more dangerous addiction.
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High school stoners have all kinds of pseudo-scientific theories about the harmlessness of cannabis. You can’t smoke yourself to death, the argument goes, the way an alcoholic can drink herself to death. Unlike meth, pot is a natural gift of Mother Gaia; unlike heroin, it’s not physically addictive; and unlike cigarettes, it’s not laced with formaldehyde. Some of these ideas are valid—it’s true that fewer than 10 percent of pot smokers will become clinically addicted—while others are, ahem, rather “doobieous.”

As legalization efforts gain traction around the country, there’s new demand for hard evidence on the health science of pot. (Marijuana is now licit in Washington and Colorado, and medical marijuana is sanctioned in 16 states, plus Washington, D.C.) Parents nervously await the dinner-table conversation in which they have to explain why it’s alright for them to roll a joint, but, as with booze and lotto tickets, their seventh-grade daughter has to wait till she’s 18. It’s a tricky topic to finesse, and an even harder policy to enforce. In his work, David Sedaris describes how drug laws went from strict to lax in his family: “‘No smoking pot’ became ‘No smoking pot in the house,’ before it finally petered out to ‘Please don’t smoke any pot in the living room.’”

Research from the National Institute on Drug Abuse, published last month in Neuropsychopharmacology, offers parents a new argument against lighting up: exposure to THC, the primary psychoactive compound in pot, encourages nicotine dependence. In other words, marijuana may be a “gateway drug” to cigarettes, which are far more addictive, and kill far more users, than the green stuff.

Marijuana is a young man’s game: Between work, kids, and the realization that “Adult Swim” really just isn’t that funny, many of even the heaviest pot smokers give up the habit by adulthood. Conversely, smoking cigarettes, like playing tennis, is a lifelong sport: According to the CDC, cancer sticks are responsible for 443,000 American deaths annually—more than HIV, drugs and alcohol, car accidents, suicides, and murders combined. The healthcare costs associated with smoking approach $96 billion.

Researchers at the NIDA exposed rats to THC for several days, and a week later offered them the ability to self-administer nicotine. Just 65 percent of control rats became addicted to self-administering nicotine, while 94 percent of THC rats did. The nicotine had a higher “reward value” for the stoner rats, too, leading them to work harder to get it.

These findings contrasted sharply previous NIDA research into the “gateway mechanism,” where THC-exposed rats were no more likely to develop cocaine or heroin addiction than non-exposed rats. The gateway hypothesis itself is widely accepted; as any recovering addict will tell you, little highs easily lead to bigger ones. But what psychologists don’t understand is whether the gateway is primarily neurological or behavioral. That is, does a pot smoker become a heroin junkie because her brain’s pleasure centers have been rewired, or simply because her boyfriend is a drug dealer and she runs in a high-risk crowd?

The recent NIDA study is important because it demonstrates that, even if THC doesn’t promote a neurochemical gateway for heroin and cocaine addiction, it does for nicotine.

Films such as “Requiem for a Dream” and “Blow” will continue to scare the bejeezus out of teenage stoners considering experimenting with heavier stuff, but the truth is, cigarettes are the more dangerous killer.

Parents and potheads, take note.

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