Explaining the declining rates of past year cannabis use in Australia: A first pass.

INTRODUCTION AND AIMS: Cannabis use rates in Australia have declined since 2001. No research to date has examined possible reasons, despite evident policy interest in understanding such a positive public health outcome. In a 'first pass' examination, five possible reasons are explored: (i) attitudinal shifts regarding the acceptability of cannabis use; (ii) regulatory or policy changes; (iii) supply/market changes; (iv) changes in other drug use that may operate as substitutes or complements to cannabis; and (v) socio-cultural factors.

METHODS: Secondary analyses from three publically available national surveys (the National Drug Strategy Household Survey 2001 to 2013, the Illicit Drug Reporting System 2004 to 2013 and the Illicit Drug Data Report 2002 to 2013) were used to explore the five reasons.

RESULTS: It appears that all five explanations are reasonable and have preliminary evidence to indicate they are worth pursuing empirically. Attitudes have not softened towards cannabis in Australia, and regulatory changes appear to have tightened. Perceived purity may have declined, and with stable prices, this suggests an increase in purity-adjusted price that would also be consistent with decreased use. The significant declines in tobacco and alcohol use in Australia, which operate as complements to cannabis, also plausibly account for the significant decrease.

DISCUSSION AND CONCLUSIONS: This work suggests future directions for cannabis research in Australia. New multi-disciplinary research that has the potential to explore multiple hypotheses simultaneously is required. [Ritter A, Sotade O. Explaining the declining rates of past year cannabis use in Australia: A first pass. Drug Alcohol Rev 2017;00:000-000].