Scientists have learned a great deal about how THC (the active ingredient in marijuana), acts in the brain to produce its many effects.
When someone smokes marijuana, THC rapidly passes from the lungs into the bloodstream, which carries the chemical to the brain and other organs throughout the body.
THC acts upon specific sites in the brain, called cannabinoid receptors, kicking off a series of cellular reactions that ultimately lead to the “high” that users experience when they smoke marijuana. Some brain areas have many cannabinoid receptors; others have few or none. The highest density of cannabinoid receptors are found in parts of the brain that influence pleasure, memory, thoughts, concentration, sensory and time perception, and coordinated movement.
Not surprisingly, marijuana intoxication can cause distorted perceptions, impaired coordination, difficulty in thinking and problem solving, and problems with learning and memory. Research has shown that marijuana’s adverse impact on learning and memory can last for days or weeks after the acute effects of the drug wear off. As a result, someone who smokes marijuana every day may be functioning at a suboptimal intellectual level all of the time.
Research on the long-term effects of marijuana abuse indicates some changes in the brain similar to those seen after long-term abuse of other major drugs. For example, cannabinoid withdrawal in chronically exposed animals leads to an increase in the activation of the stress-response system and changes in the activity of nerve cells containing dopamine.Dopamine neurons are involved in the regulation of motivation and reward, and are directly or indirectly affected by all drugs of abuse.
Addictive Potential
Long-term marijuana abuse can lead to addiction; that is, compulsive drug seeking and abuse despite its known harmful effects upon social functioning in the context of family, school, work, and recreational activities. Long-term marijuana abusers trying to quit report irritability, sleeplessness, decreased appetite, anxiety, and drug craving, all of which make it difficult to quit. These withdrawal symptoms begin within about 1 day following abstinence, peak at 2–3 days, and subside within 1 or 2 weeks following drug cessation.
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I have to respectfully disagree with this article. If you look at real life and actual science, cannabis does not cause these problems. Look at Irvin Rosenfeld. He is one of only four people who gets medicinal cannabis from the Federal government, and has consumed over 300 pounds of cannabis in his lifetime. He even has the Guinness World Record for most cannabis consumed. Despite this, he is a successful stockbroker and one of the smartest people I’ve ever talked to. If cannabis really did have such strong mental effects, he would not be able to operate at his job, which requires constant and deep analysis, yet he smokes cannabis almost 24/7, literally.
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nice, i loved reading this . looking forward for more
, but look around and see how many brain dead people are outthere 
and yes, it does slow the brain
Rob@Hemp Protein I have to disagree. Stockbrocking is a left brain function like most practical jobs. Once you learn it you know it and does not require “deep analysis” but repetition. It is high stress mind you and that’s where pot will probably help since it numbs you of stress. I’ve been addictied to pot several times in my life and have been a computer programmer and that involved deep thought and I could never smoke pot while programming. Thank heaven that I’ve been able to kick the smoking habit and have moved on. I love hemp products but not THC. It is addictive, expensive, and should be under stiffer laws.
theBozz666 i agree that marijuana can cause many of the effects mentioned but from personal use and having slight ADD and anxiety, marijuana has allowed me to focus much better in class and i am able to recall a large majority of the information and test on it just fine…all while being high. i understand why it should be illegal to drive under the influence of cannabis but in NO WAY should the laws be stiffened. if anything it should be legalized, at least for medicinal purposes. the government wouldn’t have to be spending your hard earned tax dollars prosecuting some harmless potheads. instead they could be making bank off of the profits of marijuana.
I’m guessing that the pro pot comments are left by young people. My boyfriend is 46 and a chronic, daily pot smoker since age 13. He’s from Canada, which I think its easier to obtain there and not as expensive as in the states. I love him, but when I found out more about how pot was his whole life, its sad. Initially, in his 20′s and 30′s, he was never able to finish college, but had good jobs. He ended up in bad relationships with other drug/alcohol abusers. The pot probably gave him a decreased sense of self worth, he clung on to these people and it almost cost him his life. He ended up in situations that were dangerous because of dealing pot and obtaining it. He’s been held at knife point, car jacked and almost killed. He ended up selling it most his life to other friends, associates which put him at risk for being prosecuted if caught. So, he lived a life of sneaky deception because of weed. Now at 46, his short term memory is totally shot. I can say something to him, we can go run errands and he totally forgets where we went or what we ate for breakfast. Constantly forgets entire conversations. Even after two months sober, his mind is permanently altered. I feel so sad for him. Its like he’s got the brain of a 70 year old. Can remember what happened in junior high in the 1970′s, but forgets where he parks his car. We recently got a small amount of it from a friend. We have smoked together on occasion – I’d prefer not to, but enjoy it once in a great while. I was never a chronic smoker, just dabbled in high school. Once I met him, I tried it again after 20 years without it. Its fun, but not something I prefer to do often. When we have it, he gets sneaky and very, very deceptive. Takes buds and hides them all over, then gives me the bag as proof that he won’t smoke it. I come home and he’s high anyway. Its a strange, weird thing. He promises to be casual with it, but can have an entire quarter smoked in days. Lies, sneaks it, etc. He can’t do it period or its automatically back to the old ways of doing it from the minute he’s awake until he passes out from it at night. He has no control over it and he’s an addict. Yes, pot is addictive and I’ve seen this and seen its brain damage. That article is dead on from what I’ve seen. I love this man, but its so sad to see what 30+ years of daily pot smoking has done to him.