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YOUR BRAIN ON MARIJUANA: TWO VIEWS

Neuroscience writer Laura Sanders had little idea what she was walking into when she wrote a short news story about marijuana earlier this year.  The finding was interesting if not Earth-shattering: A hormone blocks some of the intoxicating effects of marijuana in rats and mice ( SN: 2/8/14, p.  12 ).  The work, she wrote, "may lead to drugs that help people curb cannabis dependence."

The scolding began as soon as the story went up on the Science News website.  Marijuana, many online commenters said, is simply not addictive.  One wrote: "Cannabis was proven to be nonaddictive quite a long time ago....  I am sad to see a respected publication like Science News, which I read and appreciate, spreading this misinformation."

Yet, in her reporting, Sanders had heard something quite different.  Most scientists believe that marijuana can be classified as addictive ( though less so than tobacco and alcohol ), with about 10 percent of users becoming hooked.  With recent moves toward legalization and decriminalization of marijuana, it seemed well worth a deeper look at what the evidence actually shows, or doesn't show, about marijuana's dangers and how it affects the brain. 

As revealed in the feature, "High Times: Legalization trend forces review of pot's dangers," many of the "facts" that people believe to be true about marijuana are not supported by science.  And while the pro-pot lobby cherry-picks data to support its arguments ( denying marijuana's addictiveness, for example ), so too do anti-marijuana groups, which play up pot's dangers.  Studies do show that marijuana may harm the developing brains of adolescents, but there's little science to support the idea that occasional use by an adult causes lasting damage. 

What strikes Sanders is that the fierce debate over whether to legalize marijuana is largely fought by people with personalized "facts." The disagreement seems rooted in conflicting world views.  "Science can help clarify some of these issues," she says, "but for research to have an effect on policy, people must first shed their biases and actually examine the evidence.  And that seems a tall order." But, for those of us interested in truth, it's also an especially worthy one.