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Brain on drugs: SciCafe

American Museum of Natural History
(Free admission, www.amnh.org/SciCafe

It's 7 P.M. in the Gottesman Hall of Planet Earth at the American Museum of Natural History in Manhattan and almost time for the monthly SciCafe. Tonight's topic: the effects that illegal drugs such as methamphetamine and cocaine have on the brain.

The speaker is Columbia University psychologist Carl Hart. After a short introduction, Hart hits the audience with a doozy. “What many of us have been told is that drugs destroy brain cells,” he pronounces. “But the dose that's required to do that is so excessive, we don't usually see it.” In other words, he says, the doses of meth and cocaine that most drug abusers take are not enough to harm the brain.

To bolster his point, Hart mentions a famous 2004 study in the Journal of Neuroscience that found that the volumes of the brain's limbic lobes and hippocampi—regions responsible for emotion, behavior and memory—in chronic meth users were 11 and 8 percent smaller, respectively, than in people who did not use drugs. At the time, the New York Times explained this result as “a forest fire of brain damage,” but Hart counters this argument, stating that “the notion that these folks exhibit brain deficits or cognitive impairment is simply not supported by the weight of the evidence.” Changes in brain volume are not necessarily indicative of cognitive impairment, he adds. In fact, studies have consistently shown the doses of methamphetamine drug users take boost cognitive function, not the other way around.

Hart's point is provocative, but that, he says, is entirely the point: “One of the instructions I was given when I accepted this invitation was, ‘Don't bore people.’
Melinda Wenner Moyer

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