Where there’s pot smoke, there’s fire

The claim: “Marijuana has a unique impact on the developing brain. It can prime your brain for addiction to other substances.” — Surgeon General Dr. Jerome Adams.

Adams made the statement at a substance abuse conference sponsored by Oxford House, a recovery center network. PolitiFact ruling: Half True. The implications are tricky, and it’s important to note the significant limitations on marijuana research, as well as how it compares to other drugs. It may have its own, unique mechanism of “priming” adult addiction.

Still, other substances have similar effects — even if they take a different brain path to get there. And since this idea about marijuana’s priming effect is central to Adams’ broader public health campaign, emphasizing that nicotine and alcohol also could function in this manner matters even more. The statement is partially accurate but leaves out important details and context.

Discussion: This is a reiteration of the old “gateway” argument: the idea that marijuana is frequently an entry to using other, harder drugs. And the surgeon general’s emphasis comes just as many states are loosening restrictions around its medicinal and adult recreational use.

But marijuana research is limited, and this particular hypothesis is fairly controversial. But is his central thesis — marijuana has a “unique impact” on developing brains and can “prime your brain for addiction” — accurate?

Adams’ office directed us to statements from the National Institute on Drug Abuse. NIDA noted that marijuana may have a gateway effect, but that most people who use the drug don’t progress to other, harder substances, and that alcohol and nicotine appear to have a similar impact. But the surgeon general’s office was also unequivocal on a related point: “From a public health perspective, no amount of drug use is safe for the developing brain.”

The idea that marijuana can