Negative psychosocial outcomes from teen cannabis use

In a recent NCPIC survey of attendees to the annual Nimbin Mardigrass 2025 event, a pro-cannabis legalisation rally, we learnt that many lobbyists wished to draw attention to the relative harms of cannabis and alcohol. The common argument was that cannabis causes less harm than alcohol and that, if this is the case, why should alcohol be legal and cannabis not? Of course, this is also a common theme of debate in areas locally and abroad during cannabis policy discussions. It poses an interesting question and surprisingly there is little research that has focused on this particular comparison. While we have seen many comparisons between cannabis and tobacco harms, there are relatively few regarding cannabis and alcohol.

To begin, we know that cannabis and alcohol are two of the most commonly used substances by Australian adolescents. According to the most recent 2011 Australian Secondary School Students Alcohol and Drug (ASSAD) Survey, 51% of 12-17 year olds had consumed alcohol and 12.7% had used cannabis in the preceding year (16.2% had smoked tobacco). Moreover, the use of both substances extends into adulthood. According to the most recent 2013 Australian National Drug Strategy Household Survey, adults aged 18-24 years were more likely to drink at harmful levels on a single occasion than the rest of the adult population and the median age of Australians who report past year cannabis use was at 30 years.

It is clear through models such as the global burden of disease, that alcohol use could be considered more harmful than cannabis use. That is, alcohol is estimated to account for 17.7 million disability-adjusted life years (DALYs), compared to cannabis accounting for 2 million DALYs (Whiteford et al 2013). However, as Palamar and colleagues (2014) point out, these aggregate measures do not account for domains of adverse psychosocial outcomes such as mental functioning and productivity loss, legal concerns, social relationship conflicts, driving impairments or educational impact.

In a novel investigation of data from the national representative Monitoring the Future (MTF) survey of US high school students, Palamar and colleagues (2014) were able to compare alcohol and cannabis use in addition to fifteen psychosocial outcomes as well as demographic characteristics over time. Their analysis was quite complex and focused on data from five different cohorts from 2007 to 2011. In the total sample the lifetime use of alcohol and cannabis was quite common (96.8% and 60.4% respectfully).

The results showed that, in general, as frequency of use increased, the number of adverse outcomes also increased for both substances. Notably, all of the alcohol-related outcomes were significantly more prevalent among lifetime cannabis users, while only half of cannabis-related outcomes were more prevalent among lifetime alcohol users (not accounting for simultaneous use). In particular, alcohol was more likely to be associated with “behaving in ways one regrets”, “driving unsafely”, and “feeling less stable emotionally” compared to cannabis use. In contrast, “involvement with people who are a bad influence”, “having less energy or less interest in activities”, “decreased work/school performance”, “bad psychological effects”, and “hurt relationships with parents, teachers or supervisors” were more likely to be associated with cannabis use compared to alcohol use. Overall, white students and females reported higher rates of adverse outcomes compared to black and Hispanic students and males, respectively. These differences appeared greater for alcohol-related outcomes but were not trivial among cannabis-related outcomes. Finally, cannabis users were more likely than alcohol users to consistently report no problems, although the vast majority reported at least one problem.

Labelling these different outcomes as more or less harmful is difficult and the underlying reasons for any associations with particular substances was not a focus of this research. Despite this, a clear finding was that alcohol and cannabis use are each associated with separate and significant aspects of psychosocial functioning and the strength of each of these associations increased with increased frequency of use. Moreover, these different outcomes are not typically accounted for in the commonly cited estimates of society burden.

Hopefully one take-away from this research is an increased understanding that statements such as “alcohol is more harmful than cannabis” can be quite generalising. That is, these statements tend to underestimate the differences in the harms each substance can cause and how these harms can change depending on the characteristics of the individual user and how frequently they use each substance.

References

Palamar, J.J., Fenstermaker, M., Kamboukos, D., Ompad, D.C., Cleland, C.M., & Weitzman, M. (2014). Adverse psychosocial outcomes associated with drug use among US high school seniors: a comparison of alcohol and marijuana. The American journal of drug and alcohol abuse 40, 438-446.

White, V. & Bariola, E. (2012). Australian secondary school students’ use of tobacco, alcohol, and over-the-counter and illicit substances in 2011. Report prepared for the Drug Strategy Branch, Australian Government Department of Health and Ageing. Available at http://www.nationaldrugstrategy.gov.au/internet/drugstrategy/Publishing.nsf/content/BCBF6B2C638E1202CA257ACD0020E35C/$File/National%20Report_FINAL_ASSAD_7.12.pdf.

Whiteford, H.A., Degenhardt, L., Rehm, J., Baxter, A.J., Ferrari, A.J., Erskine, H.E., Charlson, F.J., et al. (2013) Global burden of disease attributable to mental and substance use disorders: findings from the Global Burden of Disease Study 2010. Lancet 382, 1575–1586.