Marihuana

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  • Publicado : 6 de noviembre de 2009
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Marijuana

“Marijuana is a green, brown, or gray mixture of dried, shredded leaves, stems, seeds, and flowers of the hemp plant. Marijuana has a chemical in it called tetrahydrocannabinol, better known as THC. All forms of marijuana are mind-altering (psychoactive). In other words, they change how the brain works. A lot of other chemicals are found in marijuana, too — about 400 of them, some ofwhich are carcinogenic.46 Marijuana is addictive with more teens in treatment with a primary diagnosis of marijuana dependence than for all other illicit drugs combined.47
Using marijuana can also lead to disturbed perceptions and thoughts, and marijuana use can worsen psychotic symptoms in people who have schizophrenia.48
Additionally, there are higher rates of depression, anxiety, and suicidalthinking among people who use marijuana when compared to people who don't use.49 Teens who started using marijuana before age 15 are more likely to suffer from anxiety and depression in early adulthood.50 A new study shows that smoking marijuana is associated with a 40% increase risk of psychosis, and the risk is greater among regular and frequent users.”
(Pot, “Above the influence”)
“How do drugswork in the brain?
Drugs are chemicals. They work in the brain by tapping into the brain's communication system and interfering with the way nerve cells normally send, receive, and process information. Some drugs, such as marijuana and heroin, can activate neurons because their chemical structure mimics that of a natural neurotransmitter. This similarity in structure "fools" receptors and allowsthe drugs to lock onto and activate the nerve cells. Although these drugs mimic brain chemicals, they don't activate nerve cells in the same way as a natural neurotransmitter, and they lead to abnormal messages being transmitted through the network.
Other drugs, such as amphetamine or cocaine, can cause the nerve cells to release abnormally large amounts of natural neurotransmitters or preventthe normal recycling of these brain chemicals, which is needed to shut off the signal between neurons. This disruption produces a greatly amplified message, ultimately disrupting communication channels. The difference in effect can be described as the difference between someone whispering into your ear and someone shouting into a microphone.
How do drugs work in the brain to produce pleasure?
Alldrugs of abuse directly or indirectly target the brain's reward system by flooding the circuit with dopamine. Dopamine is a neurotransmitter present in regions of the brain that regulate movement, emotion, cognition, motivation, and feelings of pleasure. The overstimulation of this system, which rewards our natural behaviors, produces the euphoric effects sought by people who abuse drugs andteaches them to repeat the behavior.
How does stimulation of the brain's pleasure circuit teach us to keep taking drugs?
Our brains are wired to ensure that we will repeat life-sustaining activities by associating those activities with pleasure or reward. Whenever this reward circuit is activated, the brain notes that something important is happening that needs to be remembered, and teaches us to doit again and again, without thinking about it. Because drugs of abuse stimulate the same circuit, we learn to abuse drugs in the same way.
Why are drugs more addictive than natural rewards?
When some drugs of abuse are taken, they can release 2 to 10 times the amount of dopamine that natural rewards do. In some cases, this occurs almost immediately (as when drugs are smoked or injected), and theeffects can last much longer than those produced by natural rewards. The resulting effects on the brain's pleasure circuit dwarfs those produced by naturally rewarding behaviors such as eating. The effect of such a powerful reward strongly motivates people to take drugs again and again.
What happens to your brain if you keep taking drugs?
Just as we turn down the volume on a radio that is too...
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