Smoking and drinking up to the point of drunkenness followed an inverted U-shape trajectory, with acceleration during late adolescence, a peak around 22 to 24, and then a decrease. Alcohol consumption also followed a quadratic curve, with an acceleration from age 16 to 21, then a slower increase, and then by and large a stagnation until age 29. It is noteworthy that the legal drinking age in Switzerland is 16, similar to the case in other European countries but much lower than in the United States. Age-specific 30-day prevalence rates of drinking, smoking, and cannabis use in this sample of Swiss urban adolescents and young adults are higher than those in national samples of 10th to 12th graders in U.S. studies in the years 2001–2005 (Johnston, O’Malley, Bachman, & Schulenberg, 2012). Interestingly, the 30-day rates of drunkenness are similar, and the rates for daily use of all substances seem to be lower in Switzerland than in the United States. In spite of these differences in the level of substance use, the growth trajectories for smoking, drinking, and drunkenness in both
