As individuals pass through adolescence, they undergo many physical, cognitive, social, and emotional changes. Most learn to adapt to these changes in healthy ways. For others, turmoil, conflict, and deviant behavior lead to upheaval and disorganization as they attempt to cope. Drug use as a behavior may serve many functions in this attempt to cope, and it can have many consequences. A single episode of drug use does not necessarily lead to further use—but several episodes may lead to ever increasing use, with abuse and dependence the result.

Use of a drug, age of first use, and reasons for use are all factors related to continueddrug use. Early adolescents who try one type of drug may venture on to sample a diverse number of substances. This can lead to regular use of certain drugs (e.g., daily cigarette or MARIJUANA smoking...