Additive roles of tobacco and cannabis co-use in relation to delay discounting in a sample of heavy drinkers

Steven J Nieto,Alexandra Venegas,James Mackillop,Elizabeth M Burnette,Lara A Ray

doi:10.1007/s00213-021-05993-7

Steven J Nieto, Alexandra Venegas + Show 3 more

Open Access

https://doi.org/10.1007/s00213-021-05993-7

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Abstract

RationaleAlcohol use disorder (AUD) is associated with steeper delay discounting rates; however, it is unknown whether substance co-use, particularly cannabis use, has an additive effect on discounting rates among heavy drinkers. Furthermore, it is unclear whether substance co-use and delay discounting are independently associated with AUD severity.ObjectivesThe purpose of this study was to determine whether alcohol, tobacco, and cannabis co-use impacts delay discounting rates. We also sought to determine whether substance co-use and delay discounting were associated with AUD symptom counts.MethodsThe study sample was culled from several human laboratory studies and consisted of 483 heavy drinking individuals who completed a baseline visit (prior to experimental procedures). Participants were divided into groups based on self-reported alcohol, tobacco, and cannabis use during the past 30 days: alcohol only (n = 184), alcohol + cigarettes (n = 89), alcohol + cannabis (n = 82), and tri-use (n = 128). We examined discounting rates across the 4 groups and used multiple linear regression to test whether co-use and delay discounting were associated with AUD symptoms.ResultsAfter adjusting for covariates, individuals in the alcohol + cannabis group and the tri-use group had steeper discounting rates relative to the alcohol-only group. In addition, tri-use and delay discounting rates were independently correlated with a greater number of AUD symptoms.ConclusionsDelay discounting rates were significantly greater among subgroups reporting cannabis use providing partial support for an additive effect, while also highlighting the importance of co-use substance type. Both tri-use and delay discounting were associated with greater AUD severity, which may provide relevant intervention targets.

Highlights

Substance co-use is common with ~ 80% of substance users regularly using more than one substance (Batel et al 1995; Kalman et al 2005)
Tukey post hoc tests showed that among use groups, the alcohol + cannabis group (p = 0.008) and tri-use group (p = 0.043) had steeper discounting rates compared to the alcohol-only group
Multiple linear regression was used to identify whether co-use and delay discounting were independently associated with Alcohol use disorder (AUD) symptom count while adjusting for covariates (Table 2)

Summary

Introduction

Substance co-use is common with ~ 80% of substance users regularly using more than one substance (Batel et al 1995; Kalman et al 2005). 20–25% of current smokers are considered heavy drinkers (Dawson 2000; Spillane et al 2020), and 20–50% of those with problematic alcohol use report using cannabis (Petry 2001), with the use of one independently increasing the probability of co-use of the two remaining substances within the same day (Roche et al 2019). Co-use of alcohol and tobacco is associated with adverse negative health consequences compared to those who use either drug alone, such as brain injury and cancer risk (Durazzo et al 2007; Ebbert et al 2005). Psychopharmacology co-use of alcohol and cannabis can have legal- (e.g., driving under the influence of both substances), social-, and health-related consequences (Subbaraman and Kerr 2015; Terry-McElrath et al 2014). Despite the prevalence of simultaneous nicotine and cannabis use among heavy drinkers, whether co-use impacts decision-making and choice behavior is an understudied area

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