The Brain on Drugs

Drugs are made up of chemicals that influence the behavior of cells in the brain. Normally, cells talk to each other by sending out little pieces of mail called neurotransmitters. When a cell gets enough mail it fires. Drugs can make it seem like cells have sent out more mail to other cells than they really have.

In addition to imitating the message system of the brain, drugs can also directly affect individual cells. Typically, drugs affect the cells in the reward pathway of the brain which makes a person feel happiness or pleasure.

What do specific drugs do to the brain? Drugs such as marijuana and heroin look like the chemical mail that the brain uses. These drugs make the cell think that it has gotten more mail than it really would have naturally. Other drugs, like methamphetamine and cocaine, affect the cell directly, and make a cell send a large amount of its natural mail out at once. These drugs also affect the cell's ability to recycle mail, thus leaving a greater amount of mail floating around in the system.

Which type of mail is affected most by drug use? Most drugs affect mail in the reward pathway in the brain. The neurotransmitter that is used most frequently in this area is called dopamine. Dopamine controls emotion, movement, motivation, and feelings of pleasure. When the cells in the reward pathway fire more often (because they have gotten more mail), we feel euphoria. When this area is working naturally, without the influence of drugs, it makes us feel happy for doing things such as eating, spending time with people we love, and having sex. Its purpose is to reward us for doing things that help our survival. Instead, when drugs are influencing the system we get unnaturally rewarded for things that are a detriment to our survival.

What happens to the brain over time? Over time, as a person continues to use drugs, the mail system of the brain adapts. It is getting so much mail from outside sources (the drugs) that it realizes that it doesn't have to produce as much natural mail as it once did. It starts producing less dopamine, and it reduces the number of receiving points for dopamine messages. The drug user notices that they don't get the same high as they used to or that it takes more of the drug to get the same high. This is called developing a tolerance for a drug. Furthermore, there is a decrease in the brain's natural ability to feel pleasure. Thus even regular activities that used to make the person happy, such as going dancing or watching a funny television show, don't have the same effect. This creates a cycle of drug abuse, as the person now has to turn to drugs simply to feel a normal level of happiness. Abusing drugs over a long period of time not only affects the dopamine mail in the brain, but it changes brain circuits in more essential parts of the brain. For instance, drugs also affect a mail messenger called Glutamate. Glutamate is a messenger that affects cells which are important for learning. When this system is unnaturally influenced because of drug use, a person's ability to think clearly becomes impaired, even when the person is not using the drug. The brain's systems for behavior control, decision-making, and judgment can also be negatively affected as a result of the brain over stimulation that occurs with drug use.

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