An examination of etiology of drug misuse would not be complete without consideration of assessment of the outcome variables: drug use, drug misuse, drug abuse, or drug dependence. In general, by later adulthood there is likely to be a history of many years of drug misuse or abuse among drug users. Alternatively, the history of abuse is relatively brief among youth. There are also many methods to assess drug use, misuse, and abuse among adults. The assessment of drug abuse in youth has been less often studied, yet the highest prevalence of drug abuse is during the teen and emerging adulthood years. Life circumstances during these developmental periods are different from those experienced later in adulthood. Because drug misuse among teens and emerging adults is of the highest prevalence worldwide, and because etiology, prevention, and cessation most closely interface during the teen and emerging adulthood years, this chapter focuses on assessment during these periods (12–25 years old) (Figure 9.1).

Due to relatively less assessment research specific to adolescents and emerging adults, many methods available for use with these populations are adaptations of adult interviews and questionnaires. Methods available to aid in the assessment of drug use and diagnosis of substance abuse among adolescents and emerging adults include examinations of an individual's behavioral and family characteristics, physical findings and complaints, and laboratory tests. Clinically, as with adults, assessments to determine diagnosis and treatment planning typically rely on an in-depth drug use history and psychiatric and physical examinations.