Associations between cigarette smoking and cannabis dependence: A longitudinal study of young cannabis users in the United Kingdom

H Valerie Curran,Tom P Freeman,Grace Gale,Celia J.A Morgan,Natacha D.C Shaban,Caroline J Falconer,Ravi K Das,Chandni Hindocha,Grainne Schafer

doi:10.1016/j.drugalcdep.2015.01.004

H Valerie Curran, Tom P Freeman + Show 7 more

Open Access

https://doi.org/10.1016/j.drugalcdep.2015.01.004

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Abstract

AimsTo determine the degree to which cigarette smoking predicts levels of cannabis dependence above and beyond cannabis use itself, concurrently and in an exploratory four-year follow-up, and to investigate whether cigarette smoking mediates the relationship between cannabis use and cannabis dependence. MethodsThe study was cross sectional with an exploratory follow-up in the participants’ own homes or via telephone interviews in the United Kingdom. Participants were 298 cannabis and tobacco users aged between 16 and 23; follow-up consisted of 65 cannabis and tobacco users. The primary outcome variable was cannabis dependence as measured by the Severity of Dependence Scale (SDS). Cannabis and tobacco smoking were assessed through a self-reported drug history. ResultsRegression analyses at baseline showed cigarette smoking (frequency of cigarette smoking: B=0.029, 95% CI=0.01, 0.05; years of cigarette smoking: B=0.159, 95% CI=0.05, 0.27) accounted for 29% of the variance in cannabis dependence when controlling for frequency of cannabis use. At follow-up, only baseline cannabis dependence predicted follow-up cannabis dependence (B=0.274, 95% CI=0.05, 0.53). At baseline, cigarette smoking mediated the relationship between frequency of cannabis use and dependence (B=0.0168, 95% CI=0.008, 0.288) even when controlling for possible confounding variables (B=0.0153, 95% CI=0.007, 0.027). ConclusionsCigarette smoking is related to concurrent cannabis dependence independently of cannabis use frequency. Cigarette smoking also mediates the relationship between cannabis use and cannabis dependence suggesting tobacco is a partial driver of cannabis dependence in young people who use cannabis and tobacco.

Highlights

Together, cannabis and tobacco are two of the world’s most used drugs, and despite their unique smoking relationship, relatively little is known about their combined effects
The present study aimed to investigate the degree to which cigarette smoking predicts the level of cannabis dependence above and beyond cannabis use itself, both at baseline, and in an exploratory four-year follow-up in a sample of young cannabis and tobacco users
We investigated whether the effects of cannabis use on cannabis dependence were mediated by cigarette smoking

Summary

Introduction

Cannabis and tobacco are two of the world’s most used drugs, and despite their unique smoking relationship, relatively little is known about their combined effects. There are a host of other factors which have been considered predictors of developing a CUD, for example; age of onset (Chen et al, 2005), gender (Coffey et al, 2000; von Sydow et al, 2002), impulsivity (Swift et al, 2008), mental health problems (Wittchen et al, 2007) and early onset of continued tobacco smoking (Coffey et al, 2000; Prince van Leeuwen et al, 2014; von Sydow et al, 2002). Van der Pol et al (2013) investigated a population of high risk young adult cannabis users and found that recent negative life events and social support factors such as living alone were more predictive of CUD cannabis exposure variables suggesting the existing literature on the aetiology of cannabis use disorder is limited

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