A new analysis challenges previous research that suggested teens put their long-term brainpower in danger when they smoke marijuana heavily.
Instead, the analysis indicated that the earlier findings could have been thrown off by another factor—the effect of poverty on IQ.
The author of the new analysis, Ole Rogeberg, cautioned that his theory may not hold much water. "Or, it may turn out that it explains a lot," said Rogeberg, a research economist at the Ragnar Frisch Center for Economic Research in Oslo, Norway.
The authors of the initial study responded to a request for comment with a joint statement saying they stand by their findings. "While Dr. Rogeberg's ideas are interesting, they are not supported by our data," wrote researchers Terrie Moffitt, Avshalom Caspi and Madeline Meier. Moffitt and Caspi are psychology professors at Duke University, while Meier is a postdoctoral associate there.