Pot tale of the week

On Aug. 22, the Tahoe Daily Tribune ran a story about Incline Village prohibitionist Jason Guinasso. (The piece previously appeared in the North Lake Tahoe Bonanza.) The article carried this quote from Guinasso: “At the end of the day, when we just committed to the biggest tax increase toward education, now we’re legalizing marijuana to contribute to a lack of performance and addiction? … It impacts our ability to educate.”

The article also reported, “He [Guinasso] cites a study from Duke University that tells how a person’s IQ drops 8 percentage points by using marijuana.”

The Duke study Guinasso referenced was published Aug. 27, 2012 in the Proceedings of the National Academy of Sciences.

Part of the scientific method is reproducibility—repeating an experiment or study, either by the same researcher or an independent source, to determine if the same results can be duplicated. Had Guinasso followed up, he would have learned that, so far, no one has been able to duplicate the Duke results. In fact, a few months later, the same publication reported, “Although it would be too strong to say that the results have been discredited, the methodology is flawed and the causal inference drawn from the results premature.”

Subsequently, two much larger studies by University College of London—in October 2014 and January 2016—found no evidence of any link between lower IQ and marijuana use in the young.

Among other things, the subsequent research has found that the Duke study was flawed by a small sample of heavy users and because it did not allow for environmental factors associated with low socioeconomic status, mental illness, and use of other drugs such as tobacco and alcohol. The London studies both had larger groups of test subjects.

In any event, the issue has little to do with Nevada Question Two, which makes underage use of marijuana illegal at section two, lines D and E, but prohibitionists keep using children as a campaign argument because voters tend to react strongly to such tactics.