Related Experiment Video
Updated: Jun 26, 2026

Administration of Δ9-Tetrahydrocannabinol (THC) in Adolescent and Adult Mice
Published on: August 1, 2025
Decrease in adolescent cannabis use from 2002 to 2006 and links to evenings out with friends in 31 European and North
Emmanuel Kuntsche1, Bruce Simons-Morton, Anastasios Fotiou
1Research Department, Swiss Institute for the Prevention of Alcohol and Drug Problems, Lausanne, Switzerland. ekuntsche@sfa-ispa.ch
Objective:
To compare adolescent cannabis use between 2002 and 2006 and to investigate links to the frequency of evenings spent out with friends.
Design:
The Health Behavior in School-Aged Children study, an international study carried out in collaboration with the World Health Organization/Europe.
Setting:
A total of 31 mostly European and North American countries and regions.
Participants:
A total of 93 297 students aged 15 years.
Outcome Measure:
Cannabis use in the last 12 months in relation to the mean frequency of evenings out with friends per week.
Results:
A decrease in the prevalence of cannabis use was found in most of the 31 participating countries and regions. The most marked decreases were found in England, Portugal, Switzerland, Slovenia, and Canada. Increases occurred only in Estonia, Lithuania, Malta, and among Russian girls. The more frequently adolescents reported going out with their friends in the evenings, the more likely they were to report using cannabis. This link was consistent for boys and girls and across survey years. Across countries, changes in the mean frequency of evenings spent out were strongly linked to changes in cannabis use.
Conclusions:
The findings are consistent with the hypothesis that by going out less frequently in the evenings with friends, adolescents had fewer opportunities to obtain and use cannabis. Future research is needed to learn more about the nature of evenings out with friends and related factors that might explain changes in adolescent cannabis use over time.
Related Concept Videos
Substance Use Disorders Affecting Sleep
Understanding the concepts of physical dependence,...
CNS Depressants: Alcohol and Nicotine
Drug Abuse and Addiction: Pharmacological Phenomena
Drug Dependence
Drug Control Governance: Regulatory Bodies and Their Impact
CNS Stimulants: Cocaine, Amphetamines and Cannabinoids

