Long-term users of marijuana, for purposes medicinal or mundane, take heart: though a recent study in the Proceedings of the National Academy of Sciences suggested that consistent pot smoking erodes cognitive functioning, a brand-new study of the same data, published in the same journal, finds no such link.
As the Smithsonian's Surprising Science blog explains, the data comes from a years-long tracking survey of over 1,000 people in New Zealand. Some of those folks are chronic potheads, and some of them showed drops in IQ over time, leading the first study's authors to posit a link. But correlation, as ever, is not the same as causation. In the new study, as the Smithsonian's Joseph Stromberg writes, a researcher at Norway's Frisch Center for Economic Research "analyzed the same survey results and found that the declines in cognitive abilities could be entirely attributed to socioeconomic factors. As a result, 'the true effect' of marijuana use, (the researcher) argues, 'could be zero.'"
IQ-wise, that is. In an earlier blog post, the sharp-eyed Stromberg flags another study, this one on marijuana's pain-fighting properties. Researchers at Oxford using brain-scanning MRIs found that pot doesn't actually stop pain the way aspirin or Oxycontin does; rather, it seems to distract you from feeling it as much. Sure, these are only preliminary conclusions based on a small handful of test subjects, but it makes perfect sense. What's a little pain next to the burning need to really figure out what happened at the end of Inception?