Pubdate: Tue, 11 Sep 2012 Source: Daily Nebraskan (U of NE, NE Edu) Copyright: 2012 Daily Nebraskan Contact: http://www.dailynebraskan.com/ Details: http://www.mapinc.org/media/1176 Author: Maren Westra STUDY: LONG-TERM MARIJUANA USE DECREASES IQ OF YOUTH - Teenagers hear a lot of rumors. And one of them -- marijuana use is not harmful to overall health -- has just been disproven, according to a study published Aug. 27 in the Proceedings of the National Academy of Sciences. The study followed about 1,000 people born in a one-year span between 1972 and 1973 in Dunedin, New Zealand. The results suggest those who begin using marijuana as adolescents and into adulthood experience a long-term decrease in IQ. Researchers tested the IQ of the participants at 13 years old, an age at which significant marijuana use was considered unlikely. Then, at age 18, participants returned for a survey on their use of the drug. The subjects were interviewed four more times over the next 20 years, and those who displayed marijuana dependence before the age of 18 showed an IQ drop by age 38. Those who began using marijuana after the age of 18 did not show an IQ drop. The younger the participant began using the drug, the more significant the decrease in IQ. Those who smoked regularly showed an average IQ drop of as much as eight points, and results indicated quitting use did not lead to recovery of the IQ points. Those who did not smoke gained an average of one IQ point. Allison Dering-Anderson, a pharmacist at the University of Nebraska Medical Center College of Pharmacy, has studied the effects of marijuana and read extensive literature regarding studies of the drug. She said the results of the study aren't surprising because any time a developing brain is exposed to something that affects cognition, it can be expected to suffer. She also said she's curious as to why the study didn't report on other drugs, such as LSD, heroin, cocaine or methamphetamine. Jeffrey Baldwin, a substance abuse specialist at UNMC, said the brain fully matures around age 25, so excessive marijuana use at a young age can contribute to addiction and developmental delays. "I would caution people about using marijuana at any age but especially younger people," he said. However, he said he isn't sure if the study is accurate. He said he suspects participants who admitted to smoking significant amounts of marijuana would answer fewer questions on an IQ test correctly not because their IQ was affected long-term by the drug, but because they were under its influence while taking the test. He said he believes marijuana contributes more to amotivational syndrome, which describes a loss of interest in social and academic endeavors, than permanent brain damage. The study also showed a number of participants developed a dependency on marijuana, meaning they continued to use it even after legal, social or health problems arose because of it. If teenagers don't think marijuana is addictive, "they're mistaken," Baldwin said. "High level chronic marijuana meets the DSM IV-TR criteria for addiction." DSM IV-TR is the American Psychiatric Association's "The Diagnostic and Statistical Manual of Mental Disorders" fourth-edition text revision and is used to classify mental disorders. Both Dering-Anderson and Baldwin said they want to learn more about the effects of marijuana to determine its effectiveness as a medicine. Dering-Anderson said she supports the medical use of marijuana for adults, is not yet sure if she supports it for children and doesn't have a stance on its recreational use. Baldwin said he wants more research to determine if the benefits of medical marijuana use outweigh the detriments. "It's crazy that we don't know more about this plant than we do," Dering-Anderson said, adding that it's under-researched because there's no money in doing so, because no company can legally market marijuana. "Who owns the patent? God?" she said. Marijuana smoking has also overtaken cigarette smoking, according to the study. Dering-Anderson said teenagers are getting the message that cigarettes cause lung cancer but don't think marijuana causes health problems. She referenced several studies, one titled "Cannabinoid effects on ventilation and breathlessness" by Elspeth Pickering, which showed that cannabinoid, found in marijuana, can actually be lung-protective. Regardless, she doesn't recommend recreational use of the drug, especially for those whose brains are still developing. "I'm not a proponent of young people abusing their bodies," she said. "I'm not a proponent of young people getting stoned." - --- MAP posted-by: Jay Bergstrom