A recent UK-based study says that there is no connection between non-habitual teen cannabis use and IQ. The was study conducted on 2,612 children born in the Bristol area of the United Kingdom between 1991 and 1992. Each child’s IQ was tested at the age of 8, then again at the age of 15. Each student at the age of 15 was also surveyed on their use of cannabis for this study.
Although there seemed to be correlation of lower test scores to cannabis use, the correlation was also tied to use of alcohol, tobacco, drugs, and other risky teen behaviors. After these factors were taken into account, researchers found that there was direct correlation between cannabis use and IQ. However, teens who used marijuana heavily did show measurable signs of cognitive damage. This group of heavy users showed a 3% drop in test scores as the result of using cannabis at least 50 times by the age of 15.
“People often believe that using cannabis can be very damaging to intellectual ability in the long-term, but it is extremely difficult to separate the direct effects of cannabis from other potential explanations,” researcher Claire Mokrysz explained. She went on to say that, “The belief that cannabis is particularly harmful may detract focus from and awareness of other potentially harmful behaviours.”
It may come surprising (or not) that alcohol use was found to be strongly associated with IQ decline, but no other factors were found to be predictive of IQ change. This study comes as a significant contradiction to many American studies which try to tie the drug to memory loss or long-term impaired cognition. As recent as 2012, a study by Duke University reported a link between heavy marijuana use and lower IQ scores. The study came under heavy fire by researchers who pointed out significant flaws in their methodology; not surprising considering that Duke is located in the heart of tobacco country. The study was discredited shortly after it’s publication.
With many areas of the world inching toward legalization, proper studies have a tremendous impact on public perception of cannabis. While use is restricted to adults, the prospect of losing brain cells is no less a worry to anyone using cannabis. This new study’s findings may help to curb fears of losing a few IQ points from smoking a joint. It will be presented at the European College of Neuropsychopharmacology next March.
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Among the five panelists at Saturday’s “Blunt Talk” in New York City, there appeared to be only one point of agreement: Recreational cannabis, when and if legalized, should not be available to minors. All other points were hotly and passionately debated. This was the scene at the panel discussion that took place as part of the annual New Yorker Festival.
Here are the highlights:
ON PROHIBITION OF MARIJUANA IN THE US
In a failed attempt to extract an area of agreement amongst the panelists, Patrick Radden Keefe, panel moderator and contributor to The New Yorker, asked if they could all agree that prohibition has failed.
Carl Hart, associate professor of psychology at Columbia University and member of the National Advisory Council on Drug Abuse, disagrees: “Prohibition has been largely successful. Otherwise it wouldn’t have been around for so long.” He cites several industries as making large amounts of money from prohibition: law enforcement and the prison system, for example.
Mark Kleiman, a professor of public policy at U.C.L.A., also challenged the assertion that prohibition has failed, but on a different basis than Hart. According to Kleiman, prohibition made cannabis more expensive and stigmatized to get. As a result, he argued, the fraction of problem users is lower than it otherwise would have been under alcohol-style legalization. “From that point of view,” he said, “it hasn’t been futile, but I’d say it’s no longer sustainable.”
ON MARIJUANA LEGALIZATION
“We ought to be arguing now, not about whether to legalize because we’re gonna, but how to legalize. And, at the moment, because the drug warriors are insisting ‘no absolutely not’ and the legalizers say ‘oh, you know, this stuff is great everybody should smoke it,’ we’re getting a set of legalizations on the worst possible model,” says Kleiman.
Steve DeAngelo, long-time cannabis activist, advocate, and educator, questioned the moral justification for punishing people who choose to use marijuana over alcohol. Kevin Sabet, director of the Drug Policy Institute at the University of Florida and the co-founder of SAM (Smart Approaches to Marijuana), responded to DeAngelo by discouraging the comparison of marijuana and alcohol, what he called an “unmitigated disaster,” citing that, for every dollar the US earns on alcohol tax, another ten is spent on “social costs.” DeAngelo and Sabet could agree on one thing, however: Cannabis can be used responsibly.
ON THE EFFECTS OF MARIJUANA ON THE BRAIN
“We know a lot about marijuana’s acute effects on the brain,” says Jodi Gilman, a neuroscientist and an instructor at Harvard Medical School/Massachusetts General Hospital with the Center for Addiction Medicine. “The earlier age of onset is associated with poorer outcomes. That’s been pretty consistently studied. We know that adolescents probably shouldn’t be using marijuana on a daily basis. Gilman noted many gaps in the research; most notably the absence of literature on the long-term effects of marijuana use and what amount of is safe for use.
According to Gilman, “We know that it [marijuana] can be addictive to some people. It’s not addictive to everybody, but it’s addictive particularly for young people and for heavier users.” She noted that about 9% of people who use cannabis regularly will develop problems with addiction.
ON CONDUCTING MARIJUANA RESERACH
DeAngelo and Gilman went head-to-head on the reliability of marijuana research. “The quote unquote science of cannabis has been highly politicized,” said DeAngelo. “We’ve had an unholy alliance of researchers who need to show results and get financing.” Gilman responded that scientists “generally don’t have an agenda.”
Hart stepped in noting that the problem sat not with the scientists, but with the context in which funding operates. He noted that 90% of the world’s research on drugs such as marijuana and methamphetamines are funded through the National Institutes of Drug Abuse (NIDA), whose mission is to focus specifically on the pathology of drug use, not on the benefits.