Background and methods

The prevalence of cannabis use has increased in many developed countries in recent years. In the Republic of Ireland, the most recent national survey, conducted in 2014/15, found that 27.9% of people aged 15–64 years had used cannabis at some point in their lives, with 7.7% and 4.4% having used cannabis within the last year or last month, respectively.1 Concurrent with higher rates of use, the number of people entering treatment for a cannabis use disorder (CUD) has also increased; in Ireland, for new entrants to treatment in 2017, cannabis replaced opiates as the most commonly reported primary problem drug.2 Cannabis is also now the most common substance involved in drug-related admissions to psychiatric hospitals in Ireland.3,4 As proposals to liberalise cannabis laws are currently being explored in many countries, knowledge of factors relating to patterns of cannabis use and CUD is important for informing drug policy.

A new Irish study5 determined factors associated with recent and current cannabis use and having a CUD – defined as abuse or dependence using the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). In this research, published in the European Journal of Public Health, 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. Multinomial logistic regression was used to identify factors associated with recent (last-year) and current (last-month) cannabis use compared with ever cannabis use. Binary logistic regression was used to determine factors related to CUD among current cannabis users.

Results

The weighted prevalence of ever cannabis use for the combined surveys was 18.3%, with 3.0% and 3.3% of participants indicating recent or current use, respectively. Twenty-four per cent of recent users and 41.3% of current users scored positive for a CUD – either cannabis abuse or dependence. In multivariable analysis, factors associated with both recent or current cannabis use included younger age, not having dependent children, and current use of tobacco or alcohol. In addition, a positive attitude towards cannabis legalisation was found to be significantly related to both recent and current use. Regarding problem cannabis use, key findings were that the odds ratio (OR) of having a CUD was higher among males (OR=2.01, 95% CI: 1.13–3.57); participants aged 25–34 (OR=1.88, 95% CI: 1.04–3.39) and those aged 15–24 years of age (OR=4.22, 95% CI: 2.11–8.46); and individuals who had very low educational attainment levels (OR=3.62, 95% CI: 1.93–6.77).

Conclusions

The authors noted that the high prevalence of CUD among current users found in this study is concerning but not unexpected, as research has demonstrated that greater frequency of cannabis use increases the likelihood of developing problematic use. Consequently, these findings do suggest that health professionals should have a high level of suspicion regarding the possibility of a CUD where current cannabis use is reported. Given the potential public health implications of cannabis legalisation, it is imperative that valid and reliable information on cannabis use, CUD, and cannabis-related harm is collected to ensure that the impact of any changes arising from cannabis legalisation can be accurately measured. The authors suggest that findings from this study may be used to better inform public health efforts to improve prevention of CUD and in the identification and referral of CUD clients to appropriate treatment services.

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

3 Cannabis Risk Alliance (2019) Unspoken risks of cannabis use [Letters to the Editor]. The Irish Times, 20 May 2019. Available online at:
https://www.irishtimes.com/opinion/letters/unspoken-risks-of-cannabis-use-1.3896017

4 Smyth BP, Daly A, Elmusharaf K, et al. (2020) Legislation targeting head shops selling new psychoactive substances and changes in drug-related psychiatric admissions: a national database study. Early Interv Psychiatry, 14(1): 53–60. https://www.drugsandalcohol.ie/30436/

5 Millar SR, Mongan D, O’Dwyer C, et al. (2021) Correlates of patterns of cannabis use, abuse and dependence: evidence from two national surveys in Ireland. Eur J Public Health, 31(2): 441–447. https://www.drugsandalcohol.ie/33859/