Drugs: education, prevention and policy, February 2012; 19(1): 49–58 Copyright ß 2011 Informa UK Ltd. ISSN: 0968-7637 print/1465-3370 online DOI: 10.3109/09687637.2011.614970 Characteristics and predictors of health problems from use among high-frequency cannabis users in a Canadian university student population Benedikt Fischer 1,2 Meghan Dawe 2 , Fraser Mcguire 2 , Paul A Shuper 2,3 , Wayne Jones 1 , Katherine Rudzinski 2,3 , & Ju ¨ rgen Rehm 2,3 1 Centre for Applied Research in Mental Health and Addictions, Faculty of Health Sciences, Simon Fraser University, 2400, 515 West Hastings St., Vancouver, BC V6B 5K3, Canada, 2 Centre for Addiction and Mental Health, 33 Russell St., Toronto, Ontario M6J 1H4, Canada and 3 Dalla Lana School of Public Health, University of Toronto, 155 College St., Toronto, Ontario M5T 3M7, Canada Aims: Assess key cannabis use, risk and outcome characteristics among high-frequency cannabis users within a university student sample in Toronto, Canada. Methods: N ¼ 134 active universities students (ages of 18–28) using cannabis at least three times per week were recruited by mass advertisement, tele- phone-screened and anonymously assessed by an interviewer-administered questionnaire. Relevant descriptive statistics are presented; subsequent uni- variate and multivariate logistic regression analyses (MLRA) identified independent predictors of experiencing physical or mental health problems. Findings: The majority of respondents used cannabis 45 years, almost daily and 41 times/day, socially and medically on occasion. In past 30 days, 79% used cannabis by deep inhalation, 38% drove a car after use, 45% had difficulty controlling or limit- ing use and 52% experienced negative mental/ physical health effects, with few respondents reporting any past treatment. The MLRA identi- fied ‘difficulty controlling or limiting use’ (OR ¼ 3.40, 95% CI ¼ 1.58–7.30), ‘non-white eth- nicity’ (OR ¼ 2.78, 95% CI ¼ 1.13–6.83), and ‘living with others’ (OR ¼ 2.37, 95% CI ¼ 1.02–5.55) as independent predictors (p < 0.01) of negative health problems. Conclusions: Our sample was characterized by several use-related risks and problems, which may result in long-term burden of disease. University environment may offer suitable settings for targeted interventions. Determinants of future can- nabis use and problems should be assessed in this population. INTRODUCTION Consistent with the vast majority of countries in the Western world, cannabis is the most widely used illicit psychoactive substance amongst the general population in Canada (Room, Fischer, Hall, Lenton, & Reuter, 2010). According to two recent national general population surveys, between 11% and 14% of Canadians aged 15 and older – i.e. at least one in every 10 adult Canadians – used cannabis in the past year (Adlaf, Begin, & Sawka, 2005; Health Canada, 2009).The association between cannabis use and age is widely documented in North American epidemiologi- cal studies, with use being most prevalent among adolescents and young adults (i.e. those aged 16–29 years), including secondary and post-secondary student populations (Adlaf, Begin, et al., 2005; Johnston, O’Malley, Bachman, & Schulenberg, 2009; Substance Abuse and Mental Health Services Administration (SAMHSA), 2009). In the 2008 Canadian Alcohol and Other Drug Use Monitoring Survey (CADUMS; Health Canada, 2009), 32% – i.e. as many as one in three – of those between 15 and 24 years of age reported past year cannabis use. Similar rates have been noted specifically among senior high school and university student populations (Adlaf, Demers, & Gliksman, 2005; Bell, Correspondence: Benedikt Fischer, Centre for Applied Research in Mental Health and Addictions (CARMHA), Faculty of Health Sciences, Simon Fraser University, 2400 - 515 W Hasting St., Vancouver, BC V6B 5K3, Canada. Tel: 1-778-782-5148. Fax: 1-778-782- 7768. E-mail: bfischer@sfu.ca 49