I have a Google news search set up on my homepage for the term "Marijuana." Most of the time, this just show the top five stories about the biggest grow-op or trafficking busts that occurred recently, but occasionally something a little more interesting shows up. Like Yesterday.
Yesterday, the top story was from CNN. The headline read "Heavy Marijuana Use Linked to Memory and Learning Deficits."
Plausible, but it flies in the face of most recent research on the subject, so I decided to dig. The CNN article was reporting on an article published in the journal Neurology (Published by the American Academy of Neurology). The actual data, however, does not bear out either the author's conclusions or those reported by CNN (among others, I'm just picking on them because they're a big target) that "heavy, long-term frequent cannabis use leads to subtle deficits in specific neuropsychological domains."
In fact, comparison of the results from long-tem users vs. the control group did not result in statistically signifigant differences in measured cognitive ability in 11 of the 14 tests performed. Additionally, there are serious methodological problems with this study:
1) This study involved a grand total of 64 people. 20 "long-term" users, 20 "short-term" users, and a control group of 24- not enough of a sample size to derive any kind of meaningful results.
2) Among the groups, the overall "cannabis users" group is 62.5% Male, while the control group is only 54.2% Male
3) The mean age of the "short term" group was 4 years younger than the control group, while the mean age of the "long-term" group was 4 years older than the control group.
4) The "control group" had more mean years of education than either "users" group in the study.
5) Only the "control group" had members under 21 (the youngest was 17)
So- to summarize: CNN is running a story about a study from which no meaningful conclusions can be drawn. Shame on you, CNN. The American Academy of Neurology published this study despite serious flaws in its methodology and its conclusions not being borne out by the underlying data. Shame on you, AAN. The News Media as a whole picked this up as a story and ran with it. Whatever happenned to responsible journalism? Checking sources? Doing anything more that rewording a press release? I understand that most people are cows, but I'm more likely to punch the guy with the cattle prod than to go along with the herd.