Researchers have found that children and teens (both male and female) who are physically and sexually abused are at greater risk than other young people of using marijuana and other drugs and of beginning drug use at an early age.
Researchers have found that use of marijuana and other drugs usually peaks in the late teens and early twenties, then declines in later years.
Scientists have learned a great deal about how THC acts in the brain to produce its many effects. When someone smokes marijuana, THC rapidly passes from the lungs into the bloodstream, which carries the chemical to the brain and other organs throughout the body.
Some frequent, long-term marijuana users show signs of a lack of motivation (sometimes termed "amotivational syndrome"). Their problems include not caring about what happens in their lives, no desire to work regularly, fatigue, and a lack of concern about how they look. As a result of these symptoms, some users tend to perform poorly in school or at work.