Does a reduction in alcohol use by Dutch high school students relate to higher use of tobacco and cannabis?

BACKGROUND Substance use of adolescents was investigated in a region around Amsterdam, the Netherlands, in the period 2005-2009. The study was intended to find out to what extent behaviour related to different substances are interrelated and how trends develop in different subgroups. METHODS Two cross-sectional surveys were conducted among Dutch students in the second and fourth year of secondary school, aged 13-16 [n = 1,854 in 2005; n = 2,088 in 2009] by making use of an online questionnaire including questions about alcohol consumption, tobacco use (smoking behaviour) and cannabis use. Two educational levels were included. RESULTS Decreases in alcohol consumption, tobacco and cannabis use were found between 2005 and 2009. The strongest decline was seen in alcohol consumption. Last month drinking decreased from 61.8% in 2005 to 36.5% in 2009. Last month binge drinking decreased from 38.7% in 2005 to 24.0% in 2009. Reduced alcohol consumption was found among boys and girls, for all ages and in both educational levels. Changes were strongest among 13-year-olds. Weekly or daily smoking declined between 2005 and 2009 among 13-year-olds, girls and students in the lower schooling level. Last month cannabis use decreased among girls and students in the higher schooling level. In both 2005 and 2009 clustering with alcohol consumption was found for the use of other substances. CONCLUSIONS Between 2005 and 2009 alcohol consumption strongly decreased among high school students. This may be due to the national prevention campaign which in the same period highlighted the importance of not drinking before the age of 16. The decrease in smoking and cannabis use between 2005 and 2009 may be due to clustering with alcohol consumption. A reduction in the use of alcohol in adolescence did not lead to replacement by tobacco or cannabis use.