The Prevalence and Correlates of Cannabis-Related Harms in a Nationally Representative Sample of Norwegian High School Students.

Purpose
Although adolescents are at increased risk for a wide spectrum of cannabis-related harms, comprehensive harm measures are seldom employed in studies of young people who use cannabis. This study examined the type and prevalence of cannabis-related harms and their associations with various cannabis use indicators in a sample of adolescent who use cannabis.Methods
A nationally representative sample of Norwegian high school students (N = 3,490, age 17-19 years, 48% male) reported whether they used cannabis, and if so, age of first initiation, use frequency, simultaneous use with alcohol, and whether they experienced any of the 18 possible cannabis-related harms. Associations between these harms and cannabis use indicators were analyzed using regression models while accounting for other known sociodemographic, temperamental, and substance use risks.Results
Among respondents who reported lifetime cannabis use (20%), 65% reported having experienced at least one cannabis-related harm (M = 4.7 ± 4.8). Although "Feelings of shame" (44%) and "Adverse psychoactive effects" (42%) were most frequently reported, harmed relationships (21%), unprotected/unwanted sex (17%), and school troubles (17%) were also prevalent. Early cannabis use initiation (Incidence rate ratio = 1.564, p < .01) and simultaneous use with alcohol (Incidence rate ratio = 1.385, p < .01), but not frequency of use, were associated with greater number of experienced harms.Discussion
By examining a wide range of diverse harms, our results underscore the need for a more nuanced understanding of negative consequences of cannabis use during sensitive periods of adolescent development. Prevention efforts targeting early initiation and simultaneous use of cannabis and alcohol may prove particularly useful in preventing cannabis-related harm among adolescents.