NEW YORK -- A study last year suggested that regular marijuana smoking during the teen years can lead to a long-term drop in IQ. Now a new analysis is challenging that conclusion.
The original study focused on more than 1,000 people in New Zealand. Researchers found a drop in IQ between ages 13 and 38 in participants who had become dependent on pot by age 18. The study concluded that pot may harm the adolescent brain.
Now a Norwegian researcher questions that conclusion. He says the IQ decline may have been due to socioeconomic factors like income, education and occupation. But the authors of the original study reply that they have ruled out that explanation.
The new work was published online Monday by the Proceedings of the National Academy of Sciences.