NEW YORK (January 14, 2013)--A study released last year suggested that regular marijuana smoking during the teen years could lead to a long-term drop in IQ, but a new analysis is challenging the 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 and the study concluded that pot could harm the adolescent brain.
But a Norwegian researcher is questioning the conclusion.
He says the IQ decline may have been because of such socioeconomic factors as 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.