Pot use-low IQ link challenged in study

by Randy Dotinga, Healthday Reporter
Pot use-low IQ link challenged in study
New report suggests poverty plays a role, and may have thrown off results of first study.

(HealthDay)—A new analysis challenges previous research that suggested teens put their long-term brainpower in danger when they smoke marijuana heavily.

Instead, the analysis indicated that the earlier findings could have been thrown off by another factor—the effect of poverty on IQ.

The author of the new analysis, Ole Rogeberg, cautioned that his theory may not hold much water. "Or, it may turn out that it explains a lot," said Rogeberg, a research economist at the Ragnar Frisch Center for Economic Research in Oslo, Norway.

The authors of the initial study responded to a request for comment with a joint statement saying they stand by their findings. "While Dr. Rogeberg's ideas are interesting, they are not supported by our data," wrote researchers Terrie Moffitt, Avshalom Caspi and Madeline Meier. Moffitt and Caspi are psychology professors at Duke University, while Meier is a postdoctoral associate there.

Their study, published in August in the Proceedings of the National Academy of Sciences, attracted media attention because it suggested that smoking pot has more than short-term effects on how people think.

Based on an analysis of given to more than 1,000 New Zealanders when they were 13 and 38, the Duke researchers found that those who heavily used marijuana as teens lost an average of eight IQ points over that time period. It didn't seem to matter if the teens later cut back on smoking pot or stopped using it entirely.

In the short term, people who use marijuana have and trouble focusing, research has shown. So, why wouldn't users have problems for years?

"The question reminds me of something adults say when kids make weird faces: 'Careful, or your face will stay that way,'" Rogeberg said. "It is certainly possible that in the long term, heavy cannabis use has permanent or persistent effects on the brain. But to find out what these changes are and what they mean is not easy. We can't just look at the short-term effects and assume that these gradually become fixed and permanent over time."

In his report, Rogeberg used simulation computer modeling to argue that the initial study was possibly flawed because of the effects of poverty on IQ.

"Recent research indicates that IQ and are kind of like muscular strength: strengthened if it is regularly challenged. IQ is strengthened or sustained by taking education, studying hard, spending time with smart, challenging people, doing demanding work in our jobs," he said. "Some kids, unfortunately, are burdened with a poor home environment, poor self-control and conduct problems. These kids are likely to gradually shift away from the kinds of activities and environments that would exercise their IQs."

Rogeberg, whose report appears in this week's online issue of the , suggests that the initial study didn't properly take this into account. "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," he wrote.

In their response, the Duke researchers said that only 23 percent of the people they studied were from poor families, making it unlikely that these participants threw off the overall results. And, they added, their results were the same when they only focused on people from middle-class families.

The Duke team also noted that another group shows similar results from marijuana exposure: rats. And, as they pointed out, rats don't go to school or fall into rich, middle-class or poor categories.

More information: For more about marijuana, visit the U.S. National Library of Medicine.

Paper: "Correlations between cannabis use and IQ change in the Dunedin cohort are consistent with confounding from socioeconomic status," by Ole Rogeberg, PNAS, 2013.

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baudrunner
2.6 / 5 (5) Jan 14, 2013
Rats do so fall into rich, middle class, and poor categories. you got your sewer rat, your muskrat, your alley rat, your street rat, your gated community rat, your pet rat. Come on now.

Taxi drivers who smoke pot actually have the highest IQ's in the general population. At the other end you got your politicians, your cops, your pro-establishmentarianists, etc. In between you got teachers.

You want to know, just ask.
cmn
not rated yet Jan 14, 2013
Rats do so fall into rich, middle class, and poor categories. you got your sewer rat, your muskrat, your alley rat, your street rat, your gated community rat, your pet rat. Come on now.


Uhm. Then you have lab rats, which are usually the rats used when conducting experiments. All the same environment, all the same "type" of rat.

I think a better argument against the pot/IQ connection would be in regard to the standardized IQ tests used. It could be that these pot smokers benefit in other areas of intelligence (i.e. creativity, or spacial reasoning). See the below article regarding the "IQ myth":

http://medicalxpr...yth.html
Jeddy_Mctedder
4 / 5 (2) Jan 14, 2013
i see this pattern in life time and again---

an absurd statement based on false assumptions is made, and then people are argue for an against the statement , with only about 1 in 30 people being both astute and interested enough to feel the desire to point out the underlying problem of the statement and how it's used to bait people into a false discussion.

IQ has demonstrably been proven as a hoax. the entire notion of general intelligence quotients that can be objectively tested is absurd. if you want to call pot smokers lazy amotivated thinkers , fine, but why argue about IQ. screw IQ.
JijiDuru
not rated yet Jan 14, 2013
i see this pattern in life time and again---

an absurd statement based on false assumptions is made, and then people are argue for an against the statement , with only about 1 in 30 people being both astute and interested enough to feel the desire to point out the underlying problem of the statement and how it's used to bait people into a false discussion.

IQ has demonstrably been proven as a hoax. the entire notion of general intelligence quotients that can be objectively tested is absurd. if you want to call pot smokers lazy amotivated thinkers , fine, but why argue about IQ. screw IQ.


Judging by your spelling you must be smoking it already. How's your IQ lately?!
Moebius
4 / 5 (3) Jan 15, 2013
The government has been deeply involved in a disinformation campaign about MJ since I can remember. It's how I learned to mistrust anything they say. They are liars. There should be a constitutional amendment making it illegal for the government to lie about anything. They have no need to lie. If they don't want us to know something, silence will serve them better than lies which make the people lose trust. How many people have tried other drugs when they found out everything the government said about MJ was a lie?
VendicarD
2.6 / 5 (5) Jan 15, 2013
Lying to the American people to further the Conservative ideological agenda is the highest form of patriotism.

Extremism in the defense of Liberty is no vice.
MandoZink
4 / 5 (4) Jan 15, 2013
"Recent research indicates that IQ and brainpower are kind of like muscular strength: strengthened if it is regularly challenged. IQ is strengthened or sustained by taking education, studying hard, spending time with smart, challenging people, doing demanding work in our jobs"

I'm 59 yrs old. Smoked all my life. When I do, I typically begin perusing science articles, then start investigating new terminologies and visiting educational websites for further insights. Then I may find myself programming a spreadsheet to calculate the sun's declination at noon for any day at any latitude on earth. Next I may add a secondary function for earth's rotational speed at that latitude with corrections for elevation.

Then the music I am streaming beckons me to refocus. I pick up my mandolin and begin finding new jazz chord inversions, so I write them down. I discover more. Then my wife asks me if I'm ever coming to bed.

There may also a connection between pot and incessant brain use. No kidding.
MandoZink
5 / 5 (1) Jan 15, 2013
I must admit that the previously described activities may seem of limited value to those researchers whose methodologies would endeavor to ignore them.
M_N
5 / 5 (1) Jan 15, 2013
What's the bet that Rogeberg is a pot user himself? In my experience, pot users tend to be pretty desperate to "prove" their habit isn't harmful.

As someone whose friend committed suicide after a pot-induced psycotic episode (no history of mental illness before he started using), I can assure you pot it NOT harmless.
barakn
1 / 5 (1) Jan 18, 2013
Sorry about your friend, M_N, but that doesn't mean you haven't committed a classic mistake - confusing an anecdote for a statistic. And it's not even a particularly compelling anecdote. What if your friend suffered some other sort of brain crisis that caused him to seek out pot and then kill himself?
SteveL
5 / 5 (1) Jan 20, 2013
My experience with pot users is that they on average haven't exactly been mental role models. Knowing that I don't need to reduce my cognitive capacity, I choose to abstain. Besides, I dislike the smell of the smoke. I don't drink alchohol or coffee either as I'm no fan of stimulants of any type. That said, it's difficult for me to say that what is the rule for one adult should be the rule for others. What adults do on their own time, as long as it can not harm or endanger others, is their own business. Corporations should have the ability to protect themselves though. If they feel use of any stimulant reduces or otherwise adversely effects the capacity of the physical and/or mental attributes they are paying for they should have the right to limit such use by their employees.
pjvc
not rated yet Jan 20, 2013
I would suggest smoking may influence any research. Ingestion should not imply combusting and inhaling.