There are several stages of drug use that may lead to dependence. Young people seem to move more quickly through the stages than do adults.
Experimental use - typically involves peers, done for recreational use; the user may enjoy defying parents or other authority figures.
Regular use - the user misses more and more school or work; worries about losing drug source; uses drugs to "fix" negative feelings; begins to stay away from friends and family; may change friends to those who are regular users; shows increased tolerance and ability to "handle" the drug.
Daily preoccupation - the user loses any motivation; does not care about school and work; has obvious behavior changes; thinking about drug use is more important than all other interests, including relationships; the user becomes secretive; may begin dealing drugs to help support habit; use of other, harder drugs may increase; legal problems may increase.
Dependence - cannot face daily life without drugs; denies problem; physical condition gets worse; loss of "control" over use; may become suicidal; financial and legal problems get worse; may have broken ties with family members or friends.