By

Wynne Parry /

Livescience.com/ October 26, 2011, 11:07 AM

Solved: Why pot smoking causes memory loss

Marijuana hurts memory and cognition, and a new rat study indicates this is because it causes once-coordinated brain regions to fall out of sync with each other. The result resembles the effects of schizophrenia, the neuroscientists found. 

The researchers measured the electrical activity in nerve cells of rats given a drug that mimics the effect of the psychoactive ingredient in marijuana, called tetrahydrocannabinol (THC). The drug had only subtle effects on individual brain regions; however, it disrupted the coordinated activity between regions of the brain.

Specifically, they found the drug disrupted the coordinated fluctuations in electrical activity -- called brain waves -- across the hippocampus and prefrontal cortex. The result resembled two instruments within an orchestra playing out of sync.

A lack of synchronization between the hippocampus and the prefrontal cortex -- areas of the brain associated with memory and decision-making -- is also associated with schizophrenia.

A group of severe brain disorders, schizophrenia causes people to interpret reality abnormally. Its symptoms may include a combination of hallucinations, delusions and disordered thinking and behavior, according to the Mayo Clinic.

As a result of the disruption to their brain activity, the rats became unable to make accurate decisions when navigating around a maze.

Marijuana abuse is common among sufferers of schizophrenia, the researchers say. In fact, other recent work has shown that the psychoactive ingredient of marijuana can induce some symptoms of schizophrenia in healthy volunteers, according to Matt Jones, a study researcher at the University of Bristol's School of Physiology and Pharmacology.

"These findings are therefore important for our understanding of psychiatric diseases, which may arise as a consequence of 'disorchestrated brains' and could be treated by re-tuning brain activity," Jones said of the recent work, which appears tomorrow in the Oct. 25 issue of the Journal of Neuroscience.   

"These results are an important step forward in our understanding of how rhythmic activity in the brain underlies thought processes in health and disease," said Michal Kucewicz, a study author also with the University of Bristol.  

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17 Comments Add a Comment
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mr_wiebe says:
Funny, actual THC help restore cells in the body. Also it is the type of hallucinogen that only will make you see things if you take a ridiculous amount. (smoking even a lot will not make you see things that aren't there.) While the green still appears green, you might associate the color with a different feeling/emotion now.

I bet most scientists criticizing the plant have never tried it, are extremely prejudice to all drugs, (except alcohol) and are pro-prohibition. This is sad. THC is not poisonous at all, will actually help restore the cells in your body, and relieve stress. All the positive aspects of THC totally outweigh the slight short term memory loss. How much of this chemical (not THC) was giving to these rats?
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x1134x says:
Before I want to study ANYTHING new, I use cannabis to calm my mind and help me "focus in", I never forget what I learn, and ace tests with no problems.

Study me! I'll help you see what cannabis REALLY can do. When you start out your experiment with the results you WANT already in mind, amazingly enough, you'll find it!
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yumita_yumara says:
The study contains a fair amount of DSP and as we know pokes electrodes into rats. As mentioned, instead of THC they use CP99540 - staring with a dosage of 0.30 mg per kg. If I weigh 10 stone, roughly 63 kg, I would be given a dosage of 18.9 mgs of CP99540. If this synthetic version is in fact 45 times more potent than the real stuff, this means I would mean I would have to take, relatively speaking, ~850mg of THC. That essentially means 85 joints at once [at 10mg per joint], just to begin with. Also not mentioned was the fact that the effects from this huge dosage was in fact temporary and only lasted for around two hours.
http://clear-uk.org/wp-content/uploads/2011/10/DrMattJonesKucewicz_JN2011.pdf <-- The actual study.
http://www.ncbi.nlm.nih.gov/pubmed/8614277 <-- 45 times more potent.
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AntiControl says:
Now I remember why I don't ever watch CBS TV yellow journalism.
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Wolf53570 says:
***.. this is a laugh... why pot causes memory loss... a drug that acts like thc... not even thc... *** ever damn media / gov propaganda
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cmr92 says:
What was the dosage given to the rats??!?! The synthetic chemical that "mimics the effects of THC" are most likely harmful to living things, possibly poisonous. This is exactly like the brain cell experiment with the monkeys.
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Wintermute0 says:
This is ludicrous: not even THC, but "a drug that mimics the effect." And a CBS "journalist" (government stenographer) bent over for this piece of propaganda. Remember the name Wynne Parry; may this stupid mistake haunt him/her on the Net for the rest of his/her life.
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housemusic3 says:
haha. refer madness.



"Two of my favorite things are sitting on my front porch smoking a pipe of sweet hemp, and playing my Hohner harmonica." - Abraham Lincoln (from a letter written by Lincoln during his presidency to the head of the Hohner Harmonica Company in Germany)


"Hemp is of first necessity to the wealth & protection of the country."
- Thomas Jefferson, U.S. President


"Make the most you can of the Indian Hemp seed and sow it everywhere."
- George Washington, U.S. President


"We shall, by and by, want a world of hemp more for our own consumption."
- John Adams, U.S. President


"Penalties against possession of a drug should not be more damaging to an individual than the use of the drug itself; and where they are, they should be changed. Nowhere is this more clear than in the laws against possession of marihuana in private for personal use... Therefore, I support legislation amending Federal law to eliminate all Federal criminal penalties for the possession of up to one ounce of marihuana." - Jimmy Carter, U.S. President



"Prohibition... goes beyond the bound of reason in that it attempts to control a man's appetite by legislation and makes a crime out of things that are not crimes. A prohibition law strikes a blow at the very principles upon which our government was founded" -Abraham Lincoln


"The prestige of government has undoubtedly been lowered considerably by the prohibition law. For nothing is more destructive of respect for the government and the law of the land than passing laws which cannot be enforced. It is an open secret that the dangerous increase of crime in this country is closely connected with this." - Albert Einstein quote on Hemp
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jsknow says:
There is NOT even one documented case of marijuana causing schizophrenia! This fear mongering nonsense has gone on way too long! We have access to the internet and we can easily check the facts!

Marijuana has NEVER caused even one death in all of recorded history!

Virtually every bit of anti-marijuana propaganda is nothing but pure lies. Marijuana does not cause aggressive behavior. Marijuana does not cause dangerous driving. Marijuana does not cause cancer, brain damage or any serious health problems. Marijuana prohibition does not keep kids away from marijuana, illegal dealers don't ask for ID. Marijuana is not a "gateway drug", there is absolutely NOTHING about marijuana that causes people to use other drugs. Marijuana is not addictive. In fact marijuana is one of the safest substances known! Marijuana is SAFER than many foods we consume and give to our kids all the time!

Exactly what good is this prohibition doing and who is benefiting from it?

Did you ever wonder why you see so many articles like this one, promoting fear and the drug war and virtually none about the astronomical benefits of marijuana? This will help you understand why you see so much anti-marijuana propaganda: http://www.salon.com/news/feature/2000/03/31/magazines Be sure to click the link titled: "television networks"!

End the drug war! It's NOT a war on drugs, it's a war on your Constitutional rights and FREEDOM!
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oldguy1234 replies:
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ToolMangler1 , Yet you want unlimited access to alcohol which causes psychosis, brain cell loss, and 85,000 deaths in 2007. And you want unlimited access to tobacco which causes lung cancer and 435,000 deaths in 2007. So if you cry so badly about pot use you must be bawling like a baby about alcohol and tobacco. Yet you don't want to deny them any rights or wage a war on them. That's being a phony hypocrite and fraud. Can't have it both ways anymore. This kind of propaganda from alco-drug users and tobacco-drug users is dead in 2011. Even the kids see through it now.
x1134x replies:
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oldguy1234 just owned you toolmangler1!
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Onceandawhile says:
This evidence that there becomes a disconnect between the hypocampus and prefrontal cortect during MJ intoxication, may actually point to some of its theraputic benefit (as it has been shown for instance with individuals with PTSD). The hypocamus is the site of all our conditioning, long-term memory, patterns of behavior, past traumas, constructed ways of seeing the world, etc. lie. If we can have a couple hours of experiencing the world and ourselves free from all that past abuse/conditioning/trauma, and to see things more 'the way they actually are', and in a much more present way, there may be some opportunity for healing. By being fully present with oneself and ones world, with the assistance of THC, it may re-instill a sense of beauty and hope in the world removed from all the trauma, for instance, experienced during war-time.
Further, this study did not point to any long-term memory effects, and so I am arguing is again that what this researcher has found may point to some of marijuana's benefits during the time of intoxication.
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