But is it true? Or should we have some flashing warning lights going off?
First, the basic findings: The New Zealand participants were tested for IQ at age 13 to provide an initial baseline, or reference mark. This age was chosen as likely to be before any marijuana use. The IQ test was then repeated at the age of 38. The results showed that a notable (e.g. 8 point) mental decline between the two ages was evident only for those who regularly began smoking pot before 18. In other words, if a kid at 13 had an IQ of 100 (average on most IQ scales, e.g. Stanford -Binet) then at 38 if his IQ had fallen to 92 he'd be within one standard deviation of being labeled "mentally deficient" (Marked at an IQ of 80). "Moron", technically, doesn't begin until an IQ below 70, so pardon the title of the blog - used, I admit, to grab attention.
The authors noted this is a significant finding given there are anywhere from 119 million to 224 million users in the world, as of 2010, according to UN reports.
In the U.S. alone, according to surveys (as noted in the AP press report), 23% of high school students admitted to recently smoking pot. And this is likely an under-estimate, since maybe 1 in 3 kids wouldn't admit doing it for any survey - even one promising anonymity. Even if the 23% figure is accurate, it would make pot even more popular than cigarettes.
Of course, the voices of authority chirped up. Lead author Meier warned:
"Parents should understand that their adolsecents are particularly vulnerable."
And from Staci Gruber, of Harvard-affiliated MacLean Hospital in Belmont, MA:
"The idea that marijuana harms the adolescent brain is something we believe is very likely".
She did add, to her credit, that this finding "warrants further investigation". You don't say!
Meanwhile, other innominate "experts" threw in their two cents by adding "the new research is an advance because its methods avoid criticisms of earlier work, which generally did not measure mental performance before marijuana use began."
Okay, it's time to enumerate some other problems I have with this study:
A primary one is that it's been published (according to the AP report) in the Proceedings of the National Academy of Sciences, a journal from a government agency and we know the feds are currently waging a vigorous battle against the use of medical marijuana in at least 6 states, including California and Colorado. The last straw for may Coloradans, indeed, was a recent ruling by a lower court judge that the federal anti-MJ law may trump Colorado's existing law that permits medical MJ dispensaries. Well, a bad time in the election cycle for THAT ruling!
Beyond that, the NAS is still notorious in the minds of many of us in deep politics because of their "acoustic study" after the original House Select Committee on Assassinations (1978-79) MIT team found a 95% probability for conspiracy in the JFK assassination. But no, the NAS team under Dr. Norman Ramsey entered and attempted to refute the findings of the original Weiss' team. Among the complaints of researcher W. Antony Marsh:
"The NAS did not allow any dialogue with critics to review and challenge such a study. They worked in total secrecy. In fact, they did not even make their raw materials available so that other researchers could try to duplicate their work."
The above is extremely pivotal, since in any bona fide scientific milieu, reproducibility of results is all important. Since the Ramsey analysis - whatever its merits or otherwise - lacks the benefit of confirmation, and hence can't be adopted as any "replacement" conclusion for the original. In my own book, I also go into more details on Ramsey et al's deficiencies.
Then there is the issue of selection bias. In other words, did the researchers cherry pick their results, to get the desired outcome? There are also dozens of other suspect techniques in statistics which can be employed to nudge conclusions in particular directions, especially if the sample sizes aren't properly taken into account when using a method - whether the chi-squared test, z-test or any others. I could highlight here an example noted in my book, 'The JFK Assassination: The Final Analysis' wherein I point out how the Ramsey team misidentified the nature of a Poisson distribution in their attempted criticisms of the Weisss-Barger study. (I compared their alleged Poisson, with a genuine one published by me in a 1984 paper in Solar Physics.)
One of the most notorious examples of biased statistics was for a paper produced by solar workers Sallie Baliunas and Willie Soon, which attempted to overturn or challenge an earlier IPCC result. In it, critics only later pointed out that the duo's choice of 50-year data periods, increments was egregious when the IPCC scientists already disclosed anthropogenic engendered warming requires a resolution of at 30 -year levels. In effect, Baliunas and Soon employed what we call a 'selective effects filter' to exclude the data they prefer not to deal with. Or rather, retain only that which serves their agenda and that of their corporate (and right wing) benefactors. Interested readers can read more of the kerfuffle here
Then there's the point that any one who's ever taught at college level or lower knows that alcohol, as beer or even hard liquor, are more accessible and widely used than marijuana. So why was a parallel study not performed to either: a) exclude that any of the NZ users were imbibing beer or other alcoholic beverages, or b) assessing the ability of any alcohol use to have similar effects to MJ.
Other factors are also evident since we know "de-myelination" occurs about age 11 (cf. 'Evolution's End', by John Chilton Pearce, pp. 100-101). Pearce observes (p. 101) that at age 11, "80 percent of the neural mass of the brain disappears", in preparation for new connections to be established. Thus, we end up with the same brain weight as at 18 months. This occurs as all neural structures not myelinated are removed from the scene, a kind of chemical cleaning up. The loss of mass is, of course, compensated for by greater numbers of new neural connections and hence more efficient brain operation. But Pearce still warns "use it or lose it".
Might it not be possible that some other factor makes it more plausible for teen MJ users to lose the ability for their neurons to re-establish new patterns, to replace what was lost? Have the researchers ruled out all other agents? I mentioned alcohol, but what about others? We know kids in the U.S. are into everything from licking toads' to sniffing cans of mom's hairspray. Have all these been absolutely ruled out?
Finally, a hidden "demon" lurks and threatens to hurl a major spanner into the works. That is, the finding that teen IQ seems to change over time . Did the researchers take this into full account? (It also appears that, apart from teens, IQ can change over time for people of any age.
We need to wait and see what further results are forthcoming and especially if this study's conclusions can be confirmed.