A newly published analysis out of Sweden potentially refutes a controversial Duke University study released in August 2012 and conducted in New Zealand that allegedly found regular consumption of cannabis by teenagers results in lower IQ scores in adulthood.
The original research tested over 1,000 participants for IQ at the age of 13 in 1986 and then again in 2011 when the members of the Kiwi grouping reached 38 years old. Participants were also administered five interviews between the ages of 18 and 38, which included questions about marijuana use. Researchers comparing the IQ scores of those at age 13 to those at age 38 apparently found only those who smoked pot regularly (by age 18) suffered a loss of IQ points, leading both Duke University and the mainstream media to trumpet that teen pot use is “dangerous for the developing brain.”
But not so fast – as Ole Rogeberg of the Ragnar Frisch Center for Economic Research in Oslo looked at the Duke findings from a different perspective, running a computer simulation tracing the possible influence of socioeconomic elements and level of education on IQ. And sure enough, Rogeberg found that the patterns of IQ point loss of his particular analysis were the same as the Duke study focusing solely on pot use.
In the subsequent period following Rogeberg's findings, Duke University researchers claimed to have conjured up new statistics that rule out Rogeberg's report, but Rogeberg has stated that Duke needs to conduct further research to completely rule out his hypothesis.
Rogeberg admitted that his findings may not be gospel truth but that the Duke study isn't capable of invalidating the profound effects of socioeconomic factors and education on the development of IQ in young adults compared to habitual marijuana use.
It should be noted, to its credit, the Proceedings of the National Academy of Sciences published both the original Duke study and the follow-up analysis from Oslo.