Epidemiologic data shows that 9 percent of adolescent females and 20 percent of adolescent males meet the adult diagnostic criteria for an alcohol use disorder (Co-occurrence, 2003). Among adolescents and young adults with substance disorders, between 41 percent and 65 percent also have a mental health disorder. In 90 percent of cases, the mental disorder develops before the substance abuse disorder. Adolescents with ADHD and learning disorders in combination with depression and anxiety disorders are at high risk for having a substance abuse problem. It is believed that long term substance abuse causes profound changes in brain structure and function, and that people who abuse alcohol have different brain chemistries that predispose them to drinking.
Rates and patterns of drug abuse show substantial variations with age (USDHHS, 2002). In the U.S., the average first use of mood-altering chemicals is 11.9 years for boys and 12.7 years for girls, usually under peer pressure (Teen, 2040). Children usually model the chemical use of their parents. In 2001, among youths aged 12 and 13, 3.8 percent reported current use of illicit drugs (USDHHS, 2002). Among youths aged 12 to 17, the rate of use of illicit drugs was 10.8 percent in 2001, up from 9