Is Marijuana Addictive?
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“I don’t get withdrawal. I just miss smoking it,” says one veteran pothead, an artist who can’t afford to buy as much since he and his wife lost their day jobs in the Great Recession. But another longtime toker, a college professor, says, “when I don’t smoke for a couple days, I get headaches.”
Scientists have not yet been able to explain why some people will get intoxicated compulsively and destructively, while others can take the same drug and not develop such problems. Starting use at a younger age and having had a traumatic childhood definitely increase the risks, but there are large and poorly understood variations in individuals’ personalities and neurochemistry. For similar reasons, it is hard to predict how depressed people will respond to various medications.
“It’s just like how people respond to meds. Not everything is pharmacological,” says Budney. “People are vulnerable. Some are more vulnerable than others.”
“That you have some sort of withdrawal really isn’t important,” Carl Hart avers. If treating withdrawal was all that was needed to get people to stop using a drug, he explains, it would be easy. The issue is more about how people use the drug than about the pharmacology of it.
“Whether or not our addiction is psychological, physical, or both, matters little,” Marijuana Anonymous says. “When it comes to the use of marijuana, we have lost the power of choice.”
The neurological basis for cannabis withdrawal is “still an open question,” says Lichtman. A Spanish researcher recently found that THC inhibits a brain-messenger chemical called cyclic AMP, and that quantities of cyclic AMP “overshoot” in the cerebellum during withdrawal. However, he cautions, this is just a correlation, not clear proof of changes in the brain.
Only a small percentage of marijuana users become dependent, he says, but “given the huge numbers of people smoking marijuana, even if [dependence] is a low amount, that’s still a huge number of people.”
Marijuana “doesn’t meet what I think are stringent definitions of addiction. Habit-forming it is, addicting it isn’t,” Dr. Hergenretter responds. “I have one patient out of 2,000 who describes himself as addicted to cannabis. He says that every time he gets some, he smokes it all and wants more. He’s really an exception. He’s one of the rare cases who describes a dysphoria the next day if he doesn’t smoke.”
The 9-percent dependence figure “doesn’t meet reality in any real way,” Hergenretter continues. While users develop tolerance, he explains, it’s very common for them never to increase how much or how often they smoke, and most are not “socially damaged by need for marijuana,” not compelled to use it to the point of “stealing their neighbors’ TV.”
With more than 800,000 people a year arrested for marijuana, the definition of “dependence” has been politicized, Mitch Earleywine says. “The distinction between ‘psychological’ and ‘physical’ addiction is completely invented,” he argues. “When later editions of the DSM came out, psychological was added primarily because cannabis wasn't creating withdrawal symptoms, and prohibitionists wanted there to still be some sort of cannabis dependence. So dependence suddenly became two types: ‘with physical’ and ‘without physical features.’ Essentially, if you had enough problems but didn't show tolerance or withdrawal, you could still get a dependence diagnosis.”
One of the main criteria for defining problematic drug use is continuing to get high even in the face of negative consequences. But if getting arrested is one of those consequences, responds Fred Gardner, “that’s a function of prohibition.”
Many marijuana users see risking arrest to grow, buy and smoke the herb as defying an unjust law, not a symptom of addiction.