Background and methods

Individuals who use cannabis are more likely to use other illicit substances, with several epidemiological studies showing that the use of cannabis is significantly related to the use of ‘harder’ illegal drugs, including stimulants such as cocaine and ecstasy.1 Increasingly, people entering addiction treatment are presenting with polysubstance use.2 Consequently, further research on the relationships between cannabis and stimulant use is needed to guide future regulation systems, to inform both clinical and public health practice, and to assess drug policy. This is particularly relevant in Ireland in 2021, given the rise in treatment cases presenting for cannabis use disorder (CUD) and cocaine use, as well as increases in the use of ecstasy observed among the general population.3

A 2021 Irish study4 determined the relationships between patterns of cannabis use and recent stimulant use, drawing on data from two large nationally representative surveys. The study also explored how frequency of cannabis use relates to stimulant use and whether subjects with a CUD – defined as cannabis abuse or dependence – are more likely to be recent users of cocaine or ecstasy. In this research, published in the journal PLoS One, data were analysed from Ireland’s 2010/11 and 2014/15 National Drug Prevalence Surveys, which recruited 5,134 and 7,005 individuals, respectively, aged 15 years or more, living in private households. Multivariable logistic regression analysis was used to examine the associations between patterns of cannabis use and recent stimulant use.

Results

Among survey participants who had used cannabis in the last month, 17.9% reported recent cocaine use, while almost one-quarter (23.6%) reported recent ecstasy use. There was a significant linear relationship between patterns of cannabis use and recent use of cocaine, ecstasy, or any stimulants, with last-month cannabis users displaying greater odds (OR=12.03, 95% CI: 8.15–17.78) of having recent stimulant use compared with last year (OR=4.48, 95% CI: 2.91–6.91) and former (reference) cannabis users. Greater frequency of cannabis use in the last 30 days was also significantly related to the use of stimulants. In addition, results demonstrated an association between CUD and recent use of cocaine or ecstasy (OR=2.28, 95% CI: 1.55–3.35).

Conclusions

The authors noted that relationships between recent and current use of cannabis and the use of cocaine or ecstasy were noticeably strong. As the use of cannabis with stimulants may increase the risk of negative health consequences, they suggest that education in community and medical settings about polydrug use and its increased risks may be warranted.
 

1   Kandel DB, Yamaguchi K and Klein LC (2006) Testing the gateway hypothesis. Addiction, 101(4): 470–472.

2   Health Research Board (2018) Focal Point Ireland: national report for 2017 – treatment. Dublin: Health Research Board. https://www.drugsandalcohol.ie/30589/

3   Mongan D, Millar SR and Galvin B (2021) The 2019–20 Irish National Drug and Alcohol Survey: main findings. Dublin: Health Research Board. https://www.drugsandalcohol.ie/34287/

4  Millar SR, Mongan D, O’Dwyer C, Smyth BP, Perry IJ and Galvin B (2021) Relationships between patterns of cannabis use, abuse and dependence and recent stimulant use: evidence from two national surveys in Ireland. PLoS ONE, 16(8): e0255745. https://www.drugsandalcohol.ie/34684/