12-month follow-up of an exploratory ‘brief intervention’ for high-frequency cannabis users among Canadian university students

N？=？134 frequent cannabis users were recruited from among university students in Toronto, randomized to either an oral or a written cannabis BI, or corresponding health controls, and assessed in-person at baseline, 3-months, and 12-months. N？=？72 (54？%) of the original sample were retained for follow-up analyses at 12-months where reductions in ‘deep inhalation/breathholding’ (Q？=？13.1; p？<？.05) and ‘driving after cannabis use’ (Q？=？9.3; p？<？.05) were observed in the experimental groups. Reductions for these indicators had been shown at 3-months in the experimental groups; these reductions were maintained over the year. Other indicators assessed remained overall stable in both experimental and control groups.The results confirm findings from select other studies indicating the potential for longer-term and sustained risk reduction effects of BIs for cannabis use. While further research is needed on the long-term effects of BIs, these may be a valuable – and efficient – intervention tool in a public health approach to high-risk cannabis use.