Co-use and co-quitting: predicting motivation to quit tobacco and cannabis among further education college students in the UK
Tobacco and cannabis are commonly co-used. 'Co-use' may be concurrent, i.e. both substances used in the same time period, or co-administered, i.e. both used in the same product; the latter is most common in Europe (Hindocha, 2016). Co-use appears to negatively impact quit attempts of both substances (Peters et al., 2014)., but little is known about the impact of co-use on quit motivation for each. The aim of this study is to examine predictors of motivation to quit tobacco and cannabis amongst a sample of young adults who co-use.
Three further education (vocational) colleges in London and SE England agreed to distribute an online questionnaire to assess current or recent (past six month) co-use of tobacco and cannabis. The authors’ university and each college principal granted ethical approval. All eligible participants provided detailed demographic data. Current patterns of tobacco and cannabis use were measured using the Cigarette Dependence Scale, short version (CDS-5), days in past month of cannabis use and the Cannabis Abuse Screening Test (CAST). Motivation to quit was measured using the Motivation to Stop Smoking scale (MTSS) which was then adapted for cannabis use.
Logistic regression was performed to assess the impact of six variables on motivation to quit each substance; independent variables were level of dependence (CDS-5 and CAST), motivation to quit other substance, 11 or more days of cannabis use in past month, gender and ethnicity.
To date 383 participants have responded, of whom 132 were eligible (current or recent co-users). 90% were aged 16-20, 58% were female, 58% were of Black or minority ethnicity and 62% reported a mental health problem in the past six months.
41% were daily tobacco users and 22% daily cannabis users. The majority (78%) reported co-administration in a 'joint' as the most common method of cannabis consumption, and 41% reported high potency cannabis was the most common type used. Quit attempts were low across the sample; 8% had quit both substances and 13% had made an attempt to quit both; 21% had tried to stop smoking tobacco compared to only 3% for cannabis. Results suggest that motivation to quit across the whole sample was higher for tobacco than cannabis (63% vs 19%).
Logistic regression analysis for motivation to quit tobacco using the model containing all six variables was statistically significant; x2 = 15.92, p=0.014, however no variables made a unique contribution. For motivation to quit cannabis, the model containing all variables was also statistically significant; x2 = 24.66, p=<0.001, and identified three variables which made a unique contribution. Past month use of cannabis >11 days was negatively associated with motivation to quit cannabis (B=-2.12, p=0.02, OR 0.13, [0.02, 0.72]), and CAST (B= 0.25, p=0.03, OR= 1.28, [1.02, 1.60] and CDS-5 (B=0.39, p = 0.06, OR = 1.48 [1.12, 1.96]) both had a small positive association.
The findings indicate that motivation to quit tobacco is over twice as high than for cannabis. Regular cannabis use has a small, negative association with motivation to quit cannabis, whereas increased risk of dependency on both substances has a greater, positive association. The role of tobacco dependence in problematic cannabis use requires further investigation in larger population samples.