cannabisnews.com: Very Heavy Pot Use Clouds Mental Function: Study





Very Heavy Pot Use Clouds Mental Function: Study
Posted by CN Staff on November 29, 2002 at 22:12:31 PT
By Dana Frisch
Source: Reuters Health
People who smoked unusually large amounts of marijuana performed worse on tests of mental function than their peers who smoked less pot, even after a 30-day abstinence period, according to a new report. Heavy users performed worse on 69% of the 35 tasks than light users, though their performances were not "clinically abnormal," the researchers found. The 22 participants were admitted to hospital during the course of the study and submitted to random urine tests to ensure they remained abstinent. 
Lead author Dr. Karen Bolla characterized the study group as being "unusual" because of the large number of joints they smoked per week. Heavy users smoked on average 91 joints a week, or about 13 a day, while light smokers smoked an average of 11 marijuana cigarettes a week. Bolla, who is an associate professor of neurology and psychiatry at Johns Hopkins University School of Medicine in Baltimore, Maryland, said the results cannot be generalized to social smokers or those who use pot for medicinal purposes, because they smoke far less marijuana. The potency might also differ, she said."What this study shows is that marijuana can be neurotoxic if you smoke a lot of it," Bolla told Reuters Health. She said this is particularly concerning since the average age of study participants was 22 years old, and the brain is still developing at that age. "You're putting a lot of foreign stuff in there that we don't really know what it does to a developing brain," she said.The study, published in the November issue of the journal Neurology, found that the mental functions most severely impacted were memory, executive function (overall reasoning and functioning) and manual dexterity.Bolla writes that these tasks in particular were affected because they are controlled by the hippocampus, prefrontal cortex and cerebellum. These brain areas are densely populated with cannabinoid receptors that attach to THC, the active ingredient in marijuana. In mice, excessive marijuana use might damage parts of the brain and "knock out certain kinds of neurons," said Bolla. This can lead to receptors in the brain being over-stimulated or under-stimulated, changing their response to chemical messengers in the brain, similar to what might result from a brain injury.Marijuana is the most widely used illicit drug in the US. An estimated 7 million people use marijuana weekly, according to 2000 data from the US Department of Health and Human Services.This is only the second study to examine the residual effects of marijuana use after more than a couple of days of abstinence. Dr. Harrison Pope Jr., a professor of psychiatry at Harvard Medical School and author of the other study, found no difference in performance on cognitive tests between heavy marijuana users and "control" subjects.Pope said in an interview that his "hunch" was that the difference between his results and Bolla's were the "sheer intensity" of marijuana use among the participants in Bolla's study. Heavy users in Pope's study smoked on average 1 or 1.5 joints over the course of a day.According to Pope, people who smoke a lot of marijuana and start earlier will do worse on tests of mental function. Whether the toxicity of the drug itself is responsible, or factors like being in school less and being unfamiliar with testing or being more impaired initially and turning to pot for that reason, is difficult to know, he added. Complete Title: Very Heavy Pot Use Clouds Mental Function: StudySOURCE: Neurology 2002;59:1337-1343. Source: Reuters HealthAuthor:  Dana FrischPublished: November 29, 2002Copyright: 2002 Reuters News ServiceWebsite: http://www.reuters.comContact: http://about.reuters.com/custhelp/Related Articles & Web Site:Chronic Cannabis Use in PDF Formathttp://www.freedomtoexhale.com/ccu.pdfStudy: Marijuana Eases Traumatic Memories http://cannabisnews.com/news/thread13601.shtmlPot Blocks Painful Memories, Study Says http://cannabisnews.com/news/thread13600.shtml
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Comment #7 posted by greenmed on December 01, 2002 at 01:45:44 PT
bad science
Neurotoxicity is a scary word, and a loaded term. Searching for an official U.S. government definition, I found the following in an OSHA bulletin (August, No. 3/2001):----Neurotoxicity DefinitionNeurotoxicity is defined as adverse effects on the structure or functioning of the central and/or peripheral nervous system that result from exposure to chemical substances. Neurotoxicants can cause morphological changes that lead to generalized damage to nerve cells (neuronopathy), injury to axons (axonopathy), or destruction of the myelin sheath (myelinopathy). It is well established that exposure to certain agricultural and industrial chemicals can damage the nervous system, resulting in neurological and behavioral dysfunction. Symptoms of neurotoxicity include muscle weakness, loss of sensation and motor control, tremors, alterations in cognition, and impaired functioning of the autonomic nervous system.The central nervous system (CNS) is composed of the brain and spinal cord. It is responsible for the higher functions of the nervous system (conditioned reflexes, learning, memory, judgment, and other functions of the mind). Chemicals toxic to the CNS can induce confusion, fatigue, irritability, and other behavioral changes. Methyl mercury and lead are known CNS toxicants. Exposure to these metals can also cause degenerative diseases of the brain (encephalopathy). The peripheral nervous system (PNS) includes all the nerves not in the brain or spinal cord. These nerves carry sensory information and motor impulses. Damage to the nerve fibers of the PNS can disrupt communication between the CNS and the rest of the body. The organic solvents carbon disulfide, n- hexane,and trichloroethylene can harm the PNS, resulting in weakness in the lower limbs, prickling or tingling in the limbs (paresthesia), and loss of coordination.Exposure to chemical agents can trigger a wide range of adverse effects on the nervous system. Neurotoxic substances can alter the propagation of nerve impulses the activity of neurotransmitters and can disrupt the maintenance of the myelin sheath or the synthesis of protein. As a result, neurotoxicological assessments require the adminstration of a battery of functional and observational tests. Neurotoxicity in humans is most commonly measured by neurological tests that assess cognitive, sensory, and motor function.----Clearly, claiming cannabis use leads to neurotoxicity in this sense is pure nonsense. The Hopkins study purports to demonstrate long-term "adverse effects" on CNS functioning, but actually it's more a summary of 10-year-old studies by Herkenham et al of cannabinoid receptor distribution in the brain. There are no results in this article inconsistent with the effects of THC binding to CB-1 receptors. Because of the high lipophilicity (fat-solubility) of THC, prolonged heavy use of cannabis - or Marinol(tm) for that matter - can lead to detectable THC levels up to a month or longer after cessation of use, as THC is slowly released from body fat.The new twist offered by Dr. Bolla is that THC's effects are now "neurotoxic." The only sense in which there is toxicity is in labelling the known and largely sought-after effects of THC as "adverse." This is a judgment call. To imply that cannabis "knocks out" neurons in a manner "similar to what might result from a brain injury" is misleading and simply bad science. The effects of cannabinoids are completely reversible and there is no evidence that they produce any permanent changes in the brain.Dr. Bolla's interpretation of the data leads me to believe she suffers from an addiction to NIDA grants. I feel we can reasonably dismiss this research as propaganda.
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Comment #6 posted by knox42897 on November 30, 2002 at 13:47:16 PT:
WHAT KIND ARE THEY SMOKING?
I thought I was a heavy user at around 2 or 3 grams a day. These guys must be really rich and bored. Cause if I was to smoke 13 joints a day, I wouldnt have time for anything else, gotta clean it, roll it and burn it, that all takes time. Doesn't that stock broker smoke 13 joints a day and responsible for millions of dollars. I really wonder what kind of quality these guys are smoking. I couldnt smoke 13 joints of primo weed a day, I could only do 6 or 7. But to each his own.
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Comment #5 posted by John Tyler on November 30, 2002 at 10:15:37 PT
More of the same old stories 
This is just more "junk scientific studies", twisting the stats with outrageous numbers, switching back and fourth between mouse and humans studies. The organizers of the prohibitionist media campaign, did not not get any traction with the "cannabis is bad" articles, nor with the "weed suppots terrorists" ads, nor with the more potent pot today than twenty years ago stories, now they are rolling out the old line that it makes you crazy and stupid series of articles.  What next? Maybe, that weed makes you more likely to associate with racial minorities, (wait, that is politically incorrect, it would never go over, even for Republicans). Maybe this, weed makes guys grow breasts. Paul McCartney was on TV Wednesday night. After forty years of aledged cannabis use, he still looked and sounded great and no breasts either, but he did have what looked like racial minority members in his band. Go figure.
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Comment #4 posted by mayan on November 30, 2002 at 07:19:09 PT
runnin' out of ammo...
"Lead author Dr. Karen Bolla characterized the study group as being "unusual" because of the large number of joints they smoked per week. Heavy users smoked on average 91 joints a week, or about 13 a day, while light smokers smoked an average of 11 marijuana cigarettes a week."Yes, I'd say the study group of heavy users is VERY unusual! 13 joints a day? The lack of oxygen to the brain alone would probably have an impact on one's mental functions! I've known some major heads through the years but none of them burned 13 bones a day(at least not without sharing). Heck, you could probably get brain-damage by smoking 13 joints of catnip a day! Yet another irrelevant,meaningless study. Looks like the antis are running out of ammo! The way out is the way in -Kissinger Commission? Huh?
http://www.scoop.co.nz/mason/stories/HL0211/S00185.htmThe Kissinger Bombshell - An Open Letter to 9/11 Skeptics and Doubters:
http://www.scoop.co.nz/mason/stories/HL0211/S00180.htmThe Latest Kissinger Outrage - Why is a proven liar and wanted man in charge of the 9/11 investigation? http://slate.msn.com/?id=2074678In Defense of Gore Vidal - Rosenbaum’s Penile Prose Vs Vidal’s Triumph:
http://www.scoop.co.nz/mason/stories/HL0211/S00186.htm9/11 "Conspiracies" and the Defactualisation of Analysis: http://www.mediamonitors.net/mosaddeq37.html9/11 Skeptics Unite: http://www.osamaskidneys.com/links.htmlPaul Thompson's Complete 9/11 Timeline: http://cooperativeresearch.org/completetimeline/The People's Investigation of 9/11: http://www.911pi.com/
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Comment #3 posted by p4me on November 30, 2002 at 05:34:19 PT
Does this means science proves MJ is devil's weed
Heavy users performed worse on 69% of the 35 tasks than light users, though their performances were not "clinically abnormal," the researchers foundDoes using percentages make it sound scientific? Couldn't they just say on 22 tasks? Of course this is just more crap. A reporter won't talk to people that can give first hand accounts of marijuana in their life and especially an MMJ user that has first hand knowledge that the government position is a bald-faced lie. Looking in the horses mouth was all about a definitive way of knowing a horses age especially when a seller would gladly lie about the "mileage" of a horse to make more money. There is no looking in the horses mouth with cannabis because truth would prove the political position of prohibition a hag.Smoking 91 joints a week would surely affect something. But how would you study someone that drank 91 cups of coffee a week. They would be peeing all the time, which should be a pleasant thought to the misadministration as they love people peeing.They already have 10,000 studies demonizing cannabis. My feeling is they should have analyzed the finances of someone that smokes 91 joints a week. Besides the prison stuff, being a financial drain has got to be one good reason not to use cannabis. I mean that is what this study is for isn't it- to find a reason not to use it? Or is it to somehow suggest that no clinically abnormal results are justification for prison/fines/forfeiture?Outside the laws the worse thing about MJ is its expense and who writes about that? People need to look in the horses mouth before they buy this prohibitional propaganda 24/7. The prohibitionist horse is 65 years old and worn out? The thing is about to die and in this case everything is obvious from a long way off. The demonizing is boomeranging while the real demon of prohibition only becomes more obvious in its details to the American people despite the controlled press.1
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Comment #2 posted by billos on November 30, 2002 at 03:26:18 PT:
Heavy use
Ok.. .. we've all heard, over and over and over, what heavy pot use does. Let's compare this to a study of heavy alcohol use. I'd like to know how people do on this "performance test" after an individual imbibes 13 vodka martinins every day for the same amount of time. Geez, we NEVER hear about those experiments.
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Comment #1 posted by The GCW on November 30, 2002 at 00:35:02 PT
The study did not indicate a need to cage 
even heavy cannabis useres. Even if a cannabis users smokes the whole time they are awake, caging is worse than any amount of smoking.With heavy cannabis use, "their performances were not "clinically abnormal." 
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