Bad science, and really bad reporting

Note: An article about this very study was published in the News-Gazette this week. The paper uncritically reports on this sort of flaky stuff, but rarely notes any of the numerous much more rigorous studies that suggest significant medical benefits from cannabis, because those contradict the N-G Editorial Board's assertion that cannabis has no medical value.

by Pete Guither

So, of course, everyone in the media has been gushing about the study that proves that even casual pot smoking damages the brain. Of course, that’s not even close to what the study showed, even if you accept the study itself as legitimate.

The people who really know, know better.

Here’s John Gever, Deputy Managing Editor, MedPage Today: Striking a Nerve: Bungling the Cannabis Story

Correlation does not equal causation, and a single exam cannot show a trend over time. Basic stuff, right?

But judging by coverage of a study just out in the Journal of Neuroscience, these are apparently foreign concepts for many folks in the media. [...]

Sad to say, the Society for Neuroscience (SfN), which publishes the Journal of Neuroscience, may have driven these dramatic overinterpretations by promoting the study in a press release headlined “Brain changes are associated with casual marijuana use in young adults.”

Also note that the study did not identify any cognitive or behavioral abnormalities in the cannabis users versus controls — it was strictly an MRI study.

That, however, didn’t stop senior author Hans Breiter, MD, of Northwestern from opining in the SfN press release that the study “raises a strong challenge to the idea that casual marijuana use isn’t associated with bad consequences.”

Um, no, it doesn’t — not without before-and-after MRI scans showing brain structure changes in users that differ from nonusers and documentation of functional impairments associated with those changes.

Lior Pachter, a computational biologist, was even harsher about the actual science: Does researching casual marijuana use cause brain abnormalities?

This is quite possibly the worst paper I’ve read all year (as some of my previous blog posts show I am saying something with this statement). [...]

First of all, the study has a very small sample size, with only 20 “cases” (marijuana users), a fact that is important to keep in mind in what follows. The title uses the term “recreational users” to describe them, and in the press release accompanying the article Breiter says that “Some of these people only used marijuana to get high once or twice a week. People think a little recreational use shouldn’t cause a problem, if someone is doing OK with work or school. Our data directly says this is not the case.” In fact, the majority of users in the study were smoking more than 10 joints per week. There is even a person in the study smoking more than 30 joints per week (as disclosed above, I’m not an expert on this stuff but if 30 joints per week is “recreation” then it seems to me that person is having a lot of fun). More importantly, Breiter’s statement in the press release is a lie. There is no evidence in the paper whatsoever, not even a tiny shred, that the users who were getting high once or twice a week were having any problems.

Pachter then gets into an analysis of the study’s bad math (which is completely out of my knowledge base and totally over my head, so I can’t really comment on it, but it sounds damning.

And finally:

This issue is one of the oldest in the book. There is even a wikipedia entry about it. Correlation does not imply causation. Yet despite the fact the every result in the paper is directed at testing for association, in the last sentence of the abstract they say “These data suggest that marijuana exposure, even in young recreational users, is associated with exposure-dependent alterations of the neural matrix of core reward structures and is consistent with animal studies of changes in dendritic arborization.” At a minimum, such a result would require doing a longitudinal study. Breiter takes this language to an extreme in the press release accompanying the article. I repeat the statement he made that I quoted above where I boldface the causal claim: “”Some of these people only used marijuana to get high once or twice a week. People think a little recreational use shouldn’t cause a problem, if someone is doing OK with work or school. Our data directly says this is not the case.” I believe that scientists should be sanctioned for making public statements that directly contradict the content of their papers, as appears to be the case here.

Agreed.

Copyright © 2014 Drug WarRant

http://www.drugwarrant.com/2014/04/bad-science-and-really-bad-reporting/

More on that ‘study’

by Pete Guither

The scientific malpractice and grossly ignorant reporting regarding the study of a single brain scan from 20 widely disparate marijuana smokers and 20 controls is getting a lot of pushback. Maybe there are limits after all to the deceptions that this area of research can put forward.

In the PolicyMic article Here’s the Real Story behind the ‘Marijuana-Changes-Your-Brain’ Study, which, of course, was also not the complete real story, co-researcher Jodi Gilman was defensive about one charge in particular:

Some people criticize the […] funding source, the National Institute on Drug Abuse, among others (which got a laugh out of Gilman: “Your data is your data”).

Um, no, it isn’t. At least not when the people involved are blatantly lying in press releases, among other scientific transgressions. It’s perfectly legitimate to question the funding source’s influence on those lies.

Unfortunately, the media pushes these lies out there and then mostly ignores the corrections, retractions, and criticisms. But we’re getting better at educating the people.

Here are three more interesting articles pushing back against the willful misuse of science.

The very political neuroscience of cannabis by Mark Kleiman

If instead you wanted to score points in the culture wars, push your political agenda, and perhaps please your sponsors at the National Institute on Drug Abuse and the Office of National Drug Control policy, you’d behave differently. […]

… and he goes on to describe exactly what one of the researchers did.

No, Weed Won’t Rot Your Brain by Maia Szalavitz

Here’s the first big problem. The 20 marijuana-smoking participants, who took the drug at least once a week, were deliberately selected to be healthy. If they had any marijuana-related problems—or any psychiatric problems or other issues—they were excluded from participating.

Are you beginning to see what’s wrong? Although the pot-smoking participants showed brain differences in comparison to the controls who were also selected to be normal—both groups were normal! If the smokers had any marijuana-related problems or any type of impairment, they would not have been included in the first place. Therefore, the brain changes that the researchers found were—by definition—not associated with any cognitive, emotional, or mental problems or differences.

Why the Media’s Fearmongering on Marijuana Effects on the Brain is Faulty by Paul Armentano

Such fear-mongering and sensationalism by the mainstream media in regards to the supposed harms of pot upon the brain are nothing new. It wasn’t long ago that the mainstream media was boldly claiming that cannabis use permanently lowered IQ, a finding that marijuana prohibitionists and anti-drug bureaucrats were happy to repeat ad nauseam.

Copyright © 2014 Drug WarRant

http://www.drugwarrant.com/2014/04/more-on-that-study/

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