Marijuana and IQ Loss "Study" is Discredited

So much for the scary IQ "study" that claimed teens are vulnerable to an 8-point IQ loss if they use marijuana frequently. The findings were discredited by a thorough review of the data by an outside investigator. There are solid reasons that teens should not be using marijuana regularly, unless they are ill, and these horror stories only muddy the water. Whenever you see a report on a study that claims terrible harm from marijuana, be suspicious, very suspicious. There are numerous so-called clinical investigators who I call researchstitutes (prostituting researchers) who have access to hundreds of millions of dollars from the federal health bureaucracy to fund studies designed and calculated to find harm from marijuana. This is not honest research and the sad thing is that the investigators who pull these scams justify their dishonesty with 20th century reefer madness fallacies, they believe that the end goal of discouraging marijuana use justifies them torturing data and shading results to conform to their expectations. They conduct small studies with patients populations at risk for the maladies they want to associate with marijuana and they ignore contradictory evidence and highlight insubstantial evidence, taken out of context, that seems to offer confirmation of their beliefs. When one conducts small studies, confounding variables sometimes appear and stand out because of the small number of other subjects. When larger studies are done these anomalies disappear. The dishonest researchstitutes who promote disinformation about marijuana take the unusual results when they happen to appear and assert their importance in the face of contrary evidence. Unfortunately, most news reporters are not scientifically literate enough, or even curious enough to look at the actual studies behind the scary press releases. Thank goodness there are other more honest scientists willing to devote the time and resources to double check spurious claims by sleazy, money-grubbing federal henchmen. Oh, another way bogus results are generated is by injecting rats and mice with synthetic cannabinoids (similar to the "bath salts" marketed to avoid marijuana laws) and then claiming the negative results apply to human use of marijuana.

Marijuana Study Tying Teens' Pot Use To I.Q. Drop Is Flawed, New Paper Suggests

Anytime you see a highly-publicized study that claims to have absolute proof that marijuana is harmful, be suspicious, very suspicious. There are hundreds of millions of dollars available from the federal government for researchers who seek to find damage caused by regular marijuana use. Some are honest scientists (like Dr. Donald Tashkin) who do research to find harm and instead find benefits which they report without self-censorship while others are what I term "researchstitutes" who work to support an agenda not the free discovery of knowledge. They tailor study protocols and select patient populations in order to have the best chance of producing dire results, and yet, time after time they come up with data that indicates benefits. It is almost certain that many of these misfires have never seen the light of day because as one investigator stated, you don't get funding to continue studies which show benefits. Upon closer investigation, the scary conclusions are frequently discredited, as we apparently see here. Thank goodness for honest scientists. Marijuana Study Tying Teens' Pot Use To I.Q. Drop Is Flawed, New Paper Suggests

By MALCOLM RITTER 01/14/13 03:47 PM ET EST AP

NEW YORK — A new analysis is challenging a report that suggests regular marijuana smoking during the teen years can lead to a long-term drop in IQ. The analysis says the statistical analysis behind that conclusion is flawed.

The original study, reported last August, included more than 1,000 people who'd been born in the town of Dunedin, New Zealand. Their IQ was tested at ages 13 and 38, and they were asked about marijuana use periodically between those ages.

Researchers at Duke University and elsewhere found that participants who'd reported becoming dependent on pot by age 18 showed a drop in IQ score between ages 13 and 38. The findings suggest pot is harmful to the adolescent brain, the researchers said.

Not so fast, says an analysis published online Monday by the Proceedings of the National Academy of Sciences.

Ole Rogeberg of the Ragnar Frisch Center for Economic Research in Oslo, says the IQ trend might have nothing to do with pot. Rather, it may have emerged from differences among the study participants in socioeconomic status, or SES, which involves factors like income, education and occupation, he says.

He based his paper on a computer simulation. It traced what would happen to IQ scores over time if they were affected by differences in SES in ways suggested by other research, but not by smoking marijuana. He found patterns that looked just like what the Duke study found.

In an interview, Rogeberg said he's not claiming that his alternative explanation is definitely right, just that the methods and evidence in the original study aren't enough to rule it out. He suggested further analyses the researchers could do.

via Marijuana Study Tying Teens' Pot Use To I.Q. Drop Is Flawed, New Paper Suggests.

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Dr. Wenk discusses the effects cannabis use has on the youthful, developing brain and why something that is not harmful to adults can harm teens. This is a good companion piece to the study recently released that showed that regular teen use of marijuana can lower IQ points later in life. In my chapter "Who Should Not Use Marijuana" I suggest that teens not use cannabis. People should wait until they are over 18 y.o. to seek the protective benefits that marijuana offers.  

How chemicals control your thoughts and feelings.

by Gary Wenk, Ph.D. Does it matter when you start smoking marijuana?

Does it matters whether you're a boy or a girl?

Multiple studies during the past few years have shown that adolescence is a period of particular vulnerability for the brain to the effects of many different chemicals and nutrients.  The question that parents often ask is "when is the most vulnerable period?" A recently published study measured the effects of marijuana use upon the cognitive performance of a very large group children who started smoking marijuana daily during their early adolescence, i.e. prior to age 15, as compared to those adolescents who started smoking marijuana after age 15.

Sadly, the researchers were able to recruit an impressive number of young children (104!) who fell into one of these categories. About half of these children had started using marijuana prior to age 15.  They were all tested using a sophisticated set of behavioral tasks that can determine executive functioning abilities.  Executive functioning includes those abilities that we tend to associate most often with complex thought processes. We use executive functioning to perform activities such as organizing our behaviors, planning our next action and controlling our current action (some might call this impulse control), forming strategies, paying attention to important cues in the environment, and remembering details related to what's going in our current environment. The performance of these subjects was compared with the performance of children who had never used marijuana.

The scientists carefully designed their study.  For example, subjects who were diagnosed with a significant mental disorder, were currently using psychoactive medications or had a history of head trauma with loss of consciousness, or were somehow intellectually disabled, were excluded from the study.  The patients in the three groups were carefully matched for the age they started daily marijuana use, their pattern of use, the number of years of daily use and their estimation of lifetime consumption. Finally, they were also matched for their age, years of education and IQ at the time of the testing.

The results were quite interesting.  Those children who started using marijuana prior to age 15 performed more poorly on all aspects of executive function tasks as compared to people who starting using marijuana after age 15 or those who had never used marijuana. Thus, chronic marijuana use prior to age 15 will have far more deleterious effects on complex brain functioning than if one begins using marijuana after age 15. In addition, both males and females who started regular marijuana use prior to age 15 were physically smaller in height and weight; this effect was most dramatic in the males. The effects of marijuana use prior to age 15 were still evident in people who were age 55 at the time of behavioral testing!  Why?

Prior to age 15 the brain is still developing in many substantial ways.  Indeed, that's why these scientists chose this cut-off point for their investigation. Humans have complicated brains that continue to develop and make new connections long after birth. Humans finish developing the most recently evolved brain regions last: that would include the most complex regions of our cortex, particularly the frontal lobes where executive functioning and impulse control is managed.  Overall, these few brain regions are far more vulnerable to any toxin, drug or chemical in our diet. Some regions of the frontal cortex do not finish wiring themselves for service until the early twenties for females and late twenties for males. If you ever wondered why females are charged much lower car insurance rates than males at comparable ages, this is it: the frontal lobes of females are simply "on line" many years before they are in males.

Anything that impairs the normal development of these vulnerable brain regions will impair impulse control, verbal fluency, and complex problem solving.  Furthermore, any impairment in the maturation of these abilities might continue to play a central role in the development of addictive behaviors later in life.  Taken together, these findings suggest that exposure to marijuana during critical periods of brain development will have a long term effect upon higher cognitive functions.

What was also quite surprising was that the scientists did not find differences in executive functioning abilities of people who started smoking marijuana after age 15 as compared to people who had never smoke marijuana!  Therefore, starting marijuana use after age 15 is apparently not as offensive to normal cognitive development.

© Gary L. Wenk, Ph.D. Author of Your Brain on Food (Oxford University Press, 2010)

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Dr. Wenk discusses the effects cannabis use has on the youthful, developing brain and why something that is not harmful to adults can harm teens. This is a good companion piece to the study recently released that showed that regular teen use of marijuana can lower IQ points later in life. In my chapter "Who Should Not Use Marijuana" I suggest that teens not use cannabis. People should wait until they are over 18 y.o. to seek the protective benefits that marijuana offers.  

How chemicals control your thoughts and feelings.

by Gary Wenk, Ph.D. Does it matter when you start smoking marijuana?

Does it matters whether you're a boy or a girl?

Multiple studies during the past few years have shown that adolescence is a period of particular vulnerability for the brain to the effects of many different chemicals and nutrients.  The question that parents often ask is "when is the most vulnerable period?" A recently published study measured the effects of marijuana use upon the cognitive performance of a very large group children who started smoking marijuana daily during their early adolescence, i.e. prior to age 15, as compared to those adolescents who started smoking marijuana after age 15.

Sadly, the researchers were able to recruit an impressive number of young children (104!) who fell into one of these categories. About half of these children had started using marijuana prior to age 15.  They were all tested using a sophisticated set of behavioral tasks that can determine executive functioning abilities.  Executive functioning includes those abilities that we tend to associate most often with complex thought processes. We use executive functioning to perform activities such as organizing our behaviors, planning our next action and controlling our current action (some might call this impulse control), forming strategies, paying attention to important cues in the environment, and remembering details related to what's going in our current environment. The performance of these subjects was compared with the performance of children who had never used marijuana.

The scientists carefully designed their study.  For example, subjects who were diagnosed with a significant mental disorder, were currently using psychoactive medications or had a history of head trauma with loss of consciousness, or were somehow intellectually disabled, were excluded from the study.  The patients in the three groups were carefully matched for the age they started daily marijuana use, their pattern of use, the number of years of daily use and their estimation of lifetime consumption. Finally, they were also matched for their age, years of education and IQ at the time of the testing.

The results were quite interesting.  Those children who started using marijuana prior to age 15 performed more poorly on all aspects of executive function tasks as compared to people who starting using marijuana after age 15 or those who had never used marijuana. Thus, chronic marijuana use prior to age 15 will have far more deleterious effects on complex brain functioning than if one begins using marijuana after age 15. In addition, both males and females who started regular marijuana use prior to age 15 were physically smaller in height and weight; this effect was most dramatic in the males. The effects of marijuana use prior to age 15 were still evident in people who were age 55 at the time of behavioral testing!  Why?

Prior to age 15 the brain is still developing in many substantial ways.  Indeed, that's why these scientists chose this cut-off point for their investigation. Humans have complicated brains that continue to develop and make new connections long after birth. Humans finish developing the most recently evolved brain regions last: that would include the most complex regions of our cortex, particularly the frontal lobes where executive functioning and impulse control is managed.  Overall, these few brain regions are far more vulnerable to any toxin, drug or chemical in our diet. Some regions of the frontal cortex do not finish wiring themselves for service until the early twenties for females and late twenties for males. If you ever wondered why females are charged much lower car insurance rates than males at comparable ages, this is it: the frontal lobes of females are simply "on line" many years before they are in males.

Anything that impairs the normal development of these vulnerable brain regions will impair impulse control, verbal fluency, and complex problem solving.  Furthermore, any impairment in the maturation of these abilities might continue to play a central role in the development of addictive behaviors later in life.  Taken together, these findings suggest that exposure to marijuana during critical periods of brain development will have a long term effect upon higher cognitive functions.

What was also quite surprising was that the scientists did not find differences in executive functioning abilities of people who started smoking marijuana after age 15 as compared to people who had never smoke marijuana!  Therefore, starting marijuana use after age 15 is apparently not as offensive to normal cognitive development.

© Gary L. Wenk, Ph.D. Author of Your Brain on Food (Oxford University Press, 2010)