Being the learning junky that I am I came across this amazing article on adolescent brain development. Acts for Youth Upstate Center For Excellence released a report in 2002, that found the effects of drugs and alcohol on still developing teenage brains was serious.
Your brain is still developing into your early twenties. It is still making new connections, increasing in grey matter, and building the framework of you.
One reason that teenagers have problems with drugs and alcohol may be due to the fact that their brains are not fully developed. They tend to misinterpret emotions as well as being oblivious to real consequences of their actions. The study finds that the damage to teenage brains by alcohol and drugs are long lasting and can have major effects on the make up of the brain.
The good news is that the teenage brain is still developing, and if you choose to fill it with knowledge instead of alcohol and drugs you will have amazing effect. Use it or lose it, is the main rule of the brain. If you do not continue to learn and make new connections the neurons in your brain will die. So exercise your brain and pick up a book, not a beer.