Substance experimentation in the Colorado Adoption Project

The use of illicit drugs has risen sharply among adolescents in recent years, adding urgency to the need for a better understanding of its etiology and predisposing factors. It has been suggested that adopted children may be more susceptible to adjustment problems, including substance use. The current study examined prevalence of substance use/experimentation (cigarettes, alcohol, marijuana, and other drugs) and age at first experimentation for adopted and non-adopted participants in the Colorado Adoption Project (CAP), based on telephone interview data for 526 (260 adopted and 266 non-adopted) subjects in grade 7 (average age of 12.5 years), and subsets of this sample in grades 8–12 (ages 13–17). Despite the power of the large sample sizes to detect mean differences, the only significant differences were in the proportions of individuals drinking by grades 8 and 9, and smoking by grades 9 and 10, with adopted adolescents smoking and drinking more than non-adopted adolescents. However, differences between adopted and non-adopted adolescents accounted for less than 4% of the variance in experimentation. Therefore, adoptive status in this prospective, population-based sample does not appear to be an important predictor of substance use/experimentation in adolescence.