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.