Does Marijuana Make You Stupid? Jonah Lehrer

Via Francisco Capella.

Extract:

Marijuana is currently regulated by the United States government as a Schedule I drug, placing it in the same category as heroin, MDMA and LSD. This is largely due to the first condition of Schedule I drugs, which is that the substance “has a high potential for abuse.” The language in that clause is deliberately vague. Does abuse equal addiction? Probably not, since marijuana is not addictive like other Schedule I drugs. Rats don’t self-administer the compound in a lab, it’s virtually impossible to fatally overdose on the drug, and the physiological effects of marijuana withdrawal, if they occur, are far milder than those experienced by chronic amphetamine, alcohol, nicotine or opiate users. Put another way, if “abuse” means “addiction” then cigarettes should be Schedule I, not marijuana.

Rather, the case for marijuana “abuse” has always stemmed from its cognitive effects. While cigarettes are like caffeinated smoke — they increase attention and productivity, marijuana is the drug of choice for slackers, hippies and Seth Rogen characters. In popular culture, all it takes is one hit from a bong before people become ridiculously dumb, unable to solve the simplest problems or utter a coherent sentence. Potheads eat a lot and laugh at stupid jokes. The larger worry, of course, is that such damage is enduring and that “smoking dope” permanently impedes learning and memory.

That, at least, has been the collective stereotype for decades. There’s even been some science to back it up, especially when the marijuana use begins at an early age. But now a different answer is beginning to emerge, thanks to an authoritative new study led by Robert Tait at the Australian National University. 

This study builds on previous work by Harvard researchers demonstrating that the learning and memory impairments of heavy marijuana users typically vanish within 28 days of “smoking cessation.” (The slight impairments still existed, however, one week after smoking.) While several days might sound like a long hippocampal hangover, heavy alcohol users typically experience deficits that persist for several months, if not years. In other words, heavy marijuana use appears to be a lot less damaging than alcoholism.

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