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Response to New Study: Marijuana Use In Adolescence

By August 30, 2012No Comments
English: Areas affected by THC on the brain

English: Areas affected by THC on the brain (Photo credit: Wikipedia)

The most recent study on marijuana has linked smoking marijuana in adolescence to a long-term drop in IQ. Marijuana, the innocent “natural” drug is often falsely viewed as being relatively harmless, and it’s sometimes even assumed to be a rite of passage in adolescence. Working in recovery, and being surrounded by recovery professionals, I can tell you the idea of harmlessness has been refuted time and time again. While the effects aren’t as overtly detrimental as amphetamine use or synthetic pot, there remains a definitive and negative effect on the developing brain in pot smokers, particularly when they start in adolescence—prime time for brain development.

According to the Proceedings of the National Academy of Sciences of the United States of America (PNAS),

“The purpose of the present study was to test the association between persistent cannabis use and neuropsychological decline and determine whether decline is concentrated among adolescent-onset cannabis users. Participants were members of the Dunedin Study, a prospective study of a birth cohort of 1,037 individuals followed from birth (1972/1973) to age 38 y. Cannabis use was ascertained in interviews at ages 18, 21, 26, 32, and 38 y. Neuropsychological testing was conducted at age 13 y, before initiation of cannabis use, and again at age 38 y, after a pattern of persistent cannabis use had developed.”

The results of this study confirmed that “long-term users of marijuana showed impairment in memory and attention that endure beyond the period of intoxication and worsen with increasing years of regular cannabis use.” (PDF

Marijuana effects one’s decision-making skills and judgment and negatively impacts memory and one’s ability to learn. THC, the drug found in marijuana, wreaks havoc on the brain particularly during its development period. According to NIDA Teen, “THC finds brain cells, or neurons with specific kinds of receptors called cannabinoid receptors and binds to them.” The highest concentration of cannabinoid receptors in the brain are found in the hippocampus, the cerebellum, the basil ganglia, and the cerebral cortex. These particular parts of the brain play a crucial part in the brain’s ability to learn. Negatively impacting this part of the brain, particularly while its developing, will make studying, learning new things, and remembering that which you’ve learned extraordinarily difficult. We honestly don’t need medical language to make this clear. Our Medical Director, Dr. Lewis, puts it plainly: “It’s simple…Marijuana makes you stupid.”

So, yes, this study illuminates the eminent dangers of marijuana use in adolescence and backs it up with very clean scientific data. What’s clear is this: marijuana use in adolescence is bad for your brain; marijuana use in general is bad for your brain. Debating whether or not those 8 IQ points are no big deal?  According to researchers, “For a person of average intelligence, an 8-point drop would mean ranking higher than only 29 percent of the population rather than 50 percent.”

Is a temporary high really worth this type of permanent mark on your intelligence?


The Study:



Articles used for this blog:

The Guardian

Huffington Post


Discover Magazine – blog


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