health

Addiction usually begins with a conscious choice to drink or use drugs. It
begins with a small exposure to a drug and repeated exposure to that drug.
People often turn to alcohol or other drugs to avoid whatever is bothering
them. For teenagers, this may mean pressure from friends, stress at home,
or problems at school. Teenagers may also assume that drinking or using
other drugs will help them fit in, let them overcome their shyness at parties,
or make them look more grown up. Some just like the feeling of being
high. In the long run, though, these individuals feel worse. The more they
drink and use drugs, the more problems arise, and the harder it is to stop.
By this point, however, people may feel as if they no longer have a choice,
because the urge to use alcohol or drugs has become so powerful.
To understand how alcohol and drugs can gain such a strong hold on
people, it helps to understand how these substances act inside the body.
Once a substance is taken in through drinking, smoking, injecting, or
inhaling, it travels through the bloodstream to the brain, which has its
own built-in reward mechanism. When people engage in actions that are
important for survival, such as eating, special nerve cells in the brain release
chemicals that make people feel pleasure. In this way, the brain’s response
conditions people to want to repeat these actions in order to feel pleasure.
Substances that are addictive affect the brain’s reward system. Instead
of teaching people to repeat survival behaviors, though, they “teach” them
to take more drugs. The way this happens depends on the substance that
is being used. Some drugs, such as heroin* or LSD, mimic the effects of a
natural brain chemical. Others, such as PCP, block the sending of messages
between nerve cells. Still others, such as cocaine, interfere with the molecules
that carry brain chemicals back to the nerve cells that released them.
Finally, some drugs cause brain chemicals to be released in larger amounts
than normal, such as methamphetamine, a type of amphetamine, also
known as “speed.” At first, drug use may seem to be fun, because it leads
to feelings of pleasure or relaxation. Over time, though, drug use gradually
changes the brain so that people need to take drugs just to feel normal.