Cannabis use is now reported to have previously unknown effects on a teen's brain. According to a study recently published in the American Journal of Psychiatry, the effects are both long and short term. Researchers say steady use of cannabis through a person's teen years affects problem solving, long-term memory and short-term memory manipulation. Most concerning for the researchers is the finding that there is also the possibility of a serious effect on a young person's brain that keeps them from controlling impulses. That means, they say, that these people are at greater risk of succumbing to substance abuse later in life.