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Marijuana and Your Brain?

It's not surprising that marijuana can scramble the brain. After all, the drug's effects on the mind are why some people use it. But experts are worried about the ways the drug may affect teens' brains. (2010)

By Charlotte Huff

Amy started smoking marijuana in ninth grade. After her stepfather unexpectedly died of a heart attack, Amy was upset and filled with feelings of grief. It was hard for her to get just a few hours of sleep each night. She turned to drugs.

Within a few weeks of those first puffs, Amy had become a daily smoker. She sometimes even skipped school to get high instead. Although she's been clean and drug free for almost a year now, Amy still thinks the drug's haze hasn't fully lifted. "When I read, I have to read the same thing five times to get what it's talking about," she says. Some days, she's also tempted to slide back into bad habits. "When I was using [marijuana]," Amy says, "I never used to think about any of the consequences [of things I did]."

It's not surprising that marijuana can scramble the brain. After all, the drug's effects on the mind are why some people use it. But experts are worried about the ways the drug may affect teens' brains. Some of the effects seem to last long after that last joint. Studies have specifically found problems with teens' thinking and judgment. That's something Amy has found out.

Making Changes

The good news? Today's teens are less likely to use marijuana than teens 10 years ago, according to the Centers for Disease Control and Prevention's Youth Risk Behavior Survey. Fewer than four in 10 high school students today say they have tried marijuana. But nearly half the teens asked a decade ago had tried the drug.

Between 2005 and 2007, though, the number of teens who said they used marijuana regularly (one or more times in the past month) stayed about the same from year to year. That may be because what begins as an occasional joint can become habit forming.

Marijuana causes the brain to make a feel-good chemical, says Robert Miranda Jr. He's a clinical psychologist and assistant professor at the Center for Alcohol and Addiction Studies at Brown University. That chemical is called dopamine. Chemicals in drugs can fool the brain into thinking something good for us is going on.

The main active chemical in pot is called THC (which is short for delta-9-tetra-hydrocannabinol). The chemical affects the brain, such as the part that helps control judgment, says Susan Weiss. Weiss is chief of the science policy branch for the National Institute on Drug Abuse. When you use marijuana, you might not make the best decisions, Weiss says.

Teens may be especially sensitive to marijuana's effects because their brains are still being formed, says Dr. Tom Wright. He's director of adolescent services for Rosecrance, a substance abuse treatment center in Rockford, Ill. Over time, the brain of a pot-smoking teen can develop new ways of thinking that can result in more not-so-great decisions. Those ways of thinking can be tough to change for the better, Wright explains.

Today and Tomorrow

And the decisions that teens make while high can be long lasting. Amy says she often skipped class to smoke pot. As a result, she failed some of her classes. And people close to Amy changed the way they saw her. Some members of her family still won't loan her even a few dollars. "I lost a lot of trust," she says.

But there can be even more serious effects on your life, now and forever. Think about what could happen if you got arrested, for instance, or decided to ride in a car with a driver who is drunk or high.

And that's not all. Longtime adult pot smokers said they were very unhappy with their lives, according to one study. They were less satisfied with their jobs, their relationships, and other parts of their lives than other adults. The same can go for teens. The more they use marijuana, Weiss says, the more likely they are to experience problems in different parts of their lives.

A Good Decision

Amy, now 18, is making healthier choices. She's working toward getting her high school diploma. Once she does that, she'd like to become a nurse who works with new babies and their moms. When Amy feels the urge to use drugs again, she talks about it with a counselor. She forces herself to think about what could happen if she did use. And each time, Amy makes the decision to stay clean.



Beyond the Brain

Given that marijuana contains some 400 chemicals, it's not surprising that its effects extend beyond the brain.

Gums: Smoking marijuana can really harm your gums. A recent study of marijuana use found much higher rates of gum disease by age 32 among those who regularly smoked,

Heart: Within a few moments, marijuana can boost your heart rate--typically 70 to 80 beats per minute--by 20 to 50 beats and possibly higher.

Lungs: One joint can be just as damaging to lung function as smoking at least two and a half cigarettes, according to one recent study.

Testicles: Research shows a potential line between regular marijuana use and higher risk of a type of testicular cancer.