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R E V I E W
Drug and Alcohol Review (July 2014), 33, 436–445 DOI: 10.1111/dar.12147
Recreational drug use and binge drinking: Stimulant but not cannabis intoxication is associated with excessive alcohol consumption REBECCA MCKETIN1,2, JENNY CHALMERS2, MATTHEW SUNDERLAND2 & DAVID A. BRIGHT3 1
Centre for Research on Ageing, Health and Well-Being, The Australian National University, Canberra, Australia, National Drug and Alcohol Research Centre, University of New South Wales, Sydney, Australia, 3School of Social Sciences, University of New South Wales, Sydney, Australia 2
Abstract Introduction and Aims. Binge drinking is elevated among recreational drug users, but it is not clear whether this elevation is related to intoxication with recreational drugs.We examined whether stimulant intoxication and cannabis intoxication were associated with binge drinking among young adults. Design and Methods. An online survey of 18- to 30-year-old Australians who had drunk alcohol in the past year (n = 1994) were quota sampled for: (i) past year ecstasy use (n = 497); (ii) past year cannabis (but not ecstasy) use (n = 688); and (iii) no ecstasy or cannabis use in the past year (alcohol-only group, n = 809). Binge drinking last Saturday night (five or more drinks) was compared for participants who took stimulants (ecstasy, cocaine, amphetamine or methamphetamine) or cannabis last Saturday night. Results. Ecstasy users who were intoxicated with stimulants (n = 91) were more likely to binge drink than ecstasy users who were not (n = 406) (89% vs. 67%), after adjusting for demographics, poly-drug use and intoxication with cannabis and energy drinks (adjusted odds ratio 3.1, P = 0.007), drinking a median of 20 drinks (cf. 10 drinks among other ecstasy users). Cannabis intoxication was not associated with binge drinking among cannabis users (57% vs. 55%) or ecstasy users (73% vs. 71%). Binge drinking was more common in all of these groups than in the alcohol-only group (34%). Discussion and Conclusions. Stimulant intoxication, but not cannabis intoxication, is associated with binge drinking among young adults, compounding already high rates of binge drinking among people who use these drugs. [McKetin R, Chalmers J, Sunderland M, Bright DA. Recreational drug use and binge drinking: Stimulant but not cannabis intoxication is associated with excessive alcohol consumption. Drug Alcohol Rev 2014;33:436–445] Key words: alcohol, binge, stimulants, ecstasy, cannabis.
Introduction Excessive alcohol intoxication, often referred to as heavy episodic drinking or ‘binge drinking’, accounts for the bulk of alcohol-related morbidity among young adults [1], increasing the risk of injury and some chronic diseases [2]. Definitions of binge drinking vary by country and have changed over time, but consensus currently rests at drinking in excess of around four to five drinks on a single occasion [3]. This is the lower bound at which harms are significantly increased [4,5]; however, binge drinking often involves much higher levels of alcohol consumption [6–8], especially on
Saturday evenings [9]. These more excessive levels of consumption disproportionately increase the risk of violence-related injury [10]. Research on heavy episodic drinking rarely considers the impact of concurrent illicit drug use [11].This is an oversight given the increasingly common practice of taking of recreational drugs, particularly illicit stimulant drugs, during heavy drinking sessions both in Australia [12,13] and elsewhere [14–16].This trend is thought to reflect the mainstreaming of ecstasy use [17], increased availability of cheap ecstasy (cf. expensive alcohol) and a culture of poly-pharmacy among hedonistic youngsters who seek out ways to maximise pleasure from their
Rebecca McKetin PhD, Fellow, Jenny Chalmers PhD, Senior Research Fellow, Matthew Sunderland PhD, NHMRC Early Career Research Fellow, David A. Bright PhD, Senior Lecturer. Correspondence to Dr Rebecca McKetin, Centre for Research on Ageing, Health and Well-Being, Building 63, Eggleston Road, The Australian National University, Canberra, ACT 0200, Australia. Tel: +2 612 5840; Fax: +61 2 612 51558; E-mail: [email protected] Received 17 December 2013; accepted for publication 31 March 2014. © 2014 Australasian Professional Society on Alcohol and other Drugs
Stimulant use and binge drinking
nights out [14]. In Australia, the use of ecstasy in the recreational drug scene has been supplemented with the more potent stimulants: 61% of regular ecstasy users report recent use of methamphetamine use and 40% report recent use of cocaine, in addition to the vast majority of recreational drug users smoking cannabis and drinking alcohol [18]. Intoxication with stimulants may facilitate alcohol consumption: stimulants complement the effects of alcohol, producing a longer lasting euphoria than either drug taken alone [19], offset the sedating effects of alcohol intoxication [19,20], reduce the unpleasant effects of stimulants (e.g. anxiety and agitation) [21,22] and they facilitate the desire to keep drinking alcohol [23–26]. In contrast, although cannabis use is also popular among young adults, it appears to substitute for alcohol, rather than complementing the effects of alcohol, with greater cannabis being associated with less alcohol use and vice versa [27,28].This is thought to be due to the similar pharmacological effects of alcohol and cannabis [11], in that cannabis and alcohol have an additive effect on sedation, fatigue and impairments in functioning [29–32]. Despite the increased popularity of combining recreational stimulant drugs with alcohol, no research has examined whether this practice is related to heavier drinking. Although elevated rates of binge drinking have been found among recreational illicit drug users (a relationship which appears to be generic to various types of drug use [33,34]), this research compares rates of drinking and drug use over a long time-frame (e.g. past year) and therefore it is not clear whether binge drinking co-occurs with drug intoxication (i.e. intoxication on alcohol and other drugs is complementary) or whether the two events occurred on separate occasions. The fact that the same people take drugs and drink heavily may simply reflect common risk factors for various substance use disorders [35]. Event-based research, whereby patterns of behaviour are examined within a single event or at a single timepoint, has been recently adopted to better understand factors associated with heavy drinking occasions [9].We used an event-based approach to examine whether intoxication with common recreational drugs (stimulants and cannabis) was related to concurrent heavier drinking.To do this, we compared alcohol consumption for ecstasy users who had taken stimulants last Saturday night (ecstasy, methamphetamine or cocaine) with ecstasy users who had not taken stimulants last Saturday night. Ecstasy users were chosen as a sentinel group of stimulant users because of the popularity of ecstasy use among young adults.We used the same approach to examine the relationship between cannabis intoxication and drinking, comparing alcohol consumption last Saturday night among a sample of cannabis users by
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whether or not they had smoked cannabis last Saturday night. Based on their pharmacological interaction with alcohol, we expected that stimulant intoxication, but not cannabis intoxication, would co-occur with heavier drinking. We also compared alcohol consumption in these groups with that seen in a sample of young adults who did not use ecstasy or cannabis, to gauge their relative levels of drinking. Methods Procedure Data were collected as part of a self-completed online survey about alcohol pricing that was carried out between November 2011 and March 2012 and which took approximately 20 min to complete. The survey was implemented by a commercial company (Pureprofile.com™: http://www.pureprofile.com) that reimbursed participants approximately A$4 per survey completed. Ethics approval was provided by the University of New South Wales Human Research Ethics Committee. Sample Participants were recruited through the Pureprofile Internet market research panel that included 107 604 Australians who could choose to participate in the survey if they were eligible. Eligible participants were aged 18–30 years and had used alcohol in the past year. Within these eligibility criteria, quota sampling was used to recruit equal numbers of men and women who had either: (i) used ecstasy in the past year (ecstasy users); (ii) used cannabis but not ecstasy in the past year (cannabis users); or (iii) who had not used either cannabis or ecstasy in the past year (alcohol only). Recruitment was discontinued when the number of completed surveys reached 400 for men and 400 for women in each of these three categories, or when the number of new recruits fell to below five per week. Participants who had started the survey at the time that recruitment was closed were included in the sample, resulting in over 400 participants in some quotas. In total, 2013 participants were recruited, with the quota for male ecstasy users, female ecstasy users and male cannabis users not being filled (see Supporting Information Appendix S1 for details). Participants from the cannabis and alcohol-only quota were excluded if they took stimulants last Saturday night (19 had taken methamphetamine or cocaine, see Supporting Information Appendix S1 for details) to ensure that these comparison groups would not be contaminated with the effect of stimulant intoxication. The final sample (n = 1994) included 497 ecstasy users © 2014 Australasian Professional Society on Alcohol and other Drugs
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(194 men and 303 women), 688 cannabis users (297 male and 391 female) and 809 in the alcohol-only group (401 male and 408 female). Representativeness of the sample To assess bias in our sample we compared each quota with the corresponding sample drawn from a representative survey of 26 648 Australians aged 12 years or older (the 2010 Australian National Drug Strategy Household Survey) who were surveyed via either a drop-and-collect survey or a computer-assisted telephone interview [36]. Compared with the National Drug Strategy Household Survey sample, our sample tended to be slightly older, better educated, receive more income, more likely to be married or de facto, more likely to smoke tobacco and more likely to have a history of illicit drug use (see Supporting Information Appendix S2 for details). Measures Alcohol consumption last Saturday night. The main outcome was binge drinking last Saturday night, defined as having consumed five or more drinks last Saturday night. A drink was defined as 10 g of alcohol reflecting Australian definitions of a standard drink [37]. Last Saturday night was defined as the 12-h period from 6pm on Saturday to 6am on Sunday. Questions on alcohol consumption were modified from the Australian National Drug Strategy Household Survey [36] and assessed the number of alcoholic drinks by container type (e.g. bottles, cans and glasses) for each type of beverage (beer, cider, wine, spirits, premixed spirits, premixed alcohol energy drinks, fortified wine and other types of alcohol).The total volume of alcohol consumed (grams) was calculated using the estimated volume for each container type and an estimated alcohol content for each beverage type (see Supporting Information Appendix S3 for details). Drug intoxication last Saturday night. The main predictor variables were: (i) intoxication with stimulants last Saturday night; and (ii) intoxication with cannabis last Saturday night. As done for alcohol consumption, Saturday night was defined as the 12-h period from 6pm on Saturday to 6am on Sunday. Stimulant use last Saturday night was defined as having taken ecstasy, cocaine or meth/amphetamine, determined by asking participants which of the following drugs they had used last Saturday night (yes/no): (i) ecstasy (ETC, E, Ecci, Adam, MDMA, MDDA, MDEA, Eve, etc.); (ii) cocaine (coke, crack, etc.), and (iii) methamphetamine or amphetamine (speed, meth, base, crystal, ice, amphetamine, etc.). Of the participants in the ecstasy © 2014 Australasian Professional Society on Alcohol and other Drugs
using group who had taken stimulants last Saturday night (n = 91), 29 had used ecstasy, nine had used cocaine, 17 had used meth/amphetamine, 10 had used ecstasy and meth/amphetamine, six had used ecstasy and cocaine, one had used methamphetamine and cocaine and 19 had used all three drugs. Cannabis use was defined as having reported ‘marijuana/cannabis’ use last Saturday night (yes/no). Covariates. Other measures included the Alcohol Use Disorders Identification Test (AUDIT), any use of other drugs used in the past year by drug type (heroin, cocaine, methamphetamine, hallucinogens, inhalants and tobacco) and demographics (sex, gender orientation, age, country of birth, income category, employment status, marital status, living with dependent children and highest level of education completed). A score of 8 or more on the AUDIT was used to identify participants at risk of an alcohol use disorder [38]. Information was also collected on the consumption of energy drinks, either premixed with alcohol or alone, last Saturday night, and this was coded as a binary variable reflecting the consumption of any energy drinks last Saturday night. Design To understand whether binge drinking among ecstasy users was related to stimulant intoxication we compared binge drinking for ecstasy users who had taken stimulants (n = 91) with those who had not taken stimulants (n = 406) last Saturday night. Within the ecstasy-using group, we also examined whether cannabis use last Saturday night (n = 127) was related to binge drinking. To determine whether cannabis intoxication was associated with binge drinking, we compared binge drinking for cannabis users who had smoked cannabis on the previous Saturday night (n = 138) with those who had not (n = 550). Finally, we compared binge drinking in each of these groups with the alcohol-only group (n = 809) to gauge their relative alcohol consumption. Analysis Logistic regression was used to compare groups on binge drinking and adjust for covariates. The outcome variable in these analyses was binge drinking last Saturday night (unless otherwise stated). The first analysis was conducted within the ecstasy user group, and the predictor variable was intoxication with stimulants last Saturday night (yes/no). The second analysis was conducted within the cannabis user group, and the predictor variable was intoxication with cannabis last Saturday night (yes/no). The remaining logistic
Stimulant use and binge drinking
regression analyses compared binge drinking in each of these four groups with the alcohol-only group. Missing data were assumed to be missing at random and excluded. All tests were two sided with significance set at P < 0.05. Data were analysed using stata SE Version 11.2 [39]. Results Characteristics of the sample Participants had a median age of 26 years (range 18–30 years), 45% were male, 70% were employed and the majority were born in Australia (85%) and spoke English as their main language (93%). Only 2% were from an aboriginal or Torres Strait Islander background. The majority had never been married (61%), identified as heterosexual (86%), had completed high school (84%) and had a tertiary qualification (22% had a trade qualification or diploma and 43% had a university degree). Over half (55%) of the sample were at risk of an alcohol use disorder (i.e. AUDIT score of 8+), 59% smoked tobacco and 29% had used other illicit drugs (i.e. besides cannabis and ecstasy) in the past year. Energy drinks were consumed by 21% of the sample last Saturday night, most of whom drank alcohol (88%). Drinking last Saturday night Sixty-three per cent of the sample drank alcohol last Saturday night, with three-quarters of these respondents, or 48% of the entire sample, reporting binge drinking last Saturday night. The characteristics of participants who binge drank is shown in Table 1 for each of the three groups. From Table 1, it can be seen that binge drinking was more common among participants who had an alcohol use disorder and who had consumed energy drinks last Saturday night, and it was less common among people on a low income or who were not employed. Binge drinking was more common among men than women, but this difference was not statistically significant for ecstasy users. In the alcoholonly group, there was a higher proportion of tobacco smokers who binge drank, but this was not true of either the ecstasy users or the cannabis users, all of whom had comparatively high rates of tobacco smoking. There was also a slightly high prevalence of binge drinking last Saturday night among ecstasy users who had dependent children, although only a minority of the sample fell into this category. Binge drinking among ecstasy users Ecstasy users who had taken stimulants last Saturday night were 3.9 times more likely to binge drink than
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those who had not taken ecstasy last Saturday night (89% vs. 67%; Table 2). After adjusting for demographic variables, risk of an alcohol use disorder, other illicit drug use in the past year, and cannabis and energy drink consumption last Saturday night, ecstasy users who took stimulants last Saturday night were still three times as likely to binge drink compared with their ecstasy-using peers who did not take stimulants last Saturday night (Table 3). Cannabis use last Saturday night was not significantly related to binge drinking among ecstasy users (73% vs. 71%; Table 2). Ecstasy users drank a median of 12 drinks last Saturday night, with those who took stimulants drinking a median of 20 drinks (cf. 10 drinks among ecstasy users who did not take stimulants last Saturday night). To investigate this excessive level of drinking further, we undertook a post-hoc analysis of participants who consumed 12 or more standard drinks last Saturday night (which we term ‘excessive binge drinking’). Excessive binge drinking was 2.7 times more likely among ecstasy users who took stimulants last Saturday night compared with those who did not [95% confidence interval (CI) 1.7–4.4, P < 0.001], with 69% binge drinking excessively (cf. 46% among ecstasy users who did not take stimulants last Saturday night). This effect remained significant after adjusting for all covariates [adjusted odds ratio (OR) 2.0, 95% CI 1.1–3.6, P = 0.03]. There was no association between cannabis intoxication and excessive binge drinking (adjusted OR 1.2, 95% CI 0.7–2.0, P = 0.608). Details of this analysis can be found in Supporting Information Appendix S4. Binge drinking among cannabis users Binge drinking last Saturday night was no more common among cannabis users who had smoked cannabis last Saturday night than those who had not (57% vs. 55%, OR 1.1, 95% CI 0.8–1.6, P = 0.595). This effect remained non-significant after adjusting for demographic variables, being at risk of an alcohol use disorder and other illicit drug use (adjusted OR 1.3, 95% CI 0.9–2.1, P = 0.206). Comparison with the alcohol only group Both ecstasy and cannabis users were more likely to binge drink, and to binge drink excessively, relative to the alcohol only group (Figure 1). After adjusting for covariates (demographics, tobacco use and energy drink consumption last Saturday night) the odds of binge drinking was 7.5 times greater for ecstasy users who had taken stimulants last Saturday night than for the alcohol only group (95% CI 2.2–25.7, P = 0.010). It was only twice as high for ecstasy users who had not taken stimulants last Saturday (adjusted OR 2.0, 95% © 2014 Australasian Professional Society on Alcohol and other Drugs
© 2014 Australasian Professional Society on Alcohol and other Drugs
0 (0) 0 (0) 26*** (72) 62*** (171) 38*** (105) 0 (0) 0 (0) 4 (11) 27 (18–30) 57** (158) 5 (15) 43 (118) 22 (61) 88 (244) 21 (58) 49 (137) 18 (50) 76* (211) 36* (85) 22** (52)
0 (0) 0 (0) 8 (40) 17 (93) 23 (123) 0 (0) 0 (0) 2 (12) 27 (18–30) 46 (243) 9 (49) 43 (230) 21 (112) 89 (473) 18 (95) 50 (268) 20 (104) 69 (368) 27 (118) 34 (145)
25 (18–30) 37 (113) 17 (52) 35 (109) 25 (77) 77 (236) 23 (72) 31 (95) 12 (37) 59 (183) 20 (53) 41 (109)
76 (234) 100 (308) 0 (0) 24 (75)
0 (0) 19 (59) 9 (29) 44 (134)
26 (18–30) 48** (184) 19 (72) 34 (131) 20 (76) 82 (310) 27 (102) 38 (144) 12 (45) 71** (270) 27 (91) 29** (100)
79 (299) 100 (380) 0 (0) 24 (90)
0 (0) 21 (79) 30*** (114) 79*** (301)
25 (18–30) 34 (48) 21 (30) 32 (46) 14 (20) 82 (117) 21 (30) 38 (54) 8 (11) 66 (94) 27 (33) 31 (37)
80 (114) 78 (111) 100 (142) 72 (102)
7 (0) 24 (34) 16 (23) 62 (88)
No (n = 142)
26 (18–30) 41 (146) 19 (69) 30 (105) 22* (78) 85 (300) 23 (81) 44 (157) 14 (49) 79** (280) 31 (101) 20* (65)
83 (296) 76 (269) 100 (355) 79 (279)
23*** (81) 26 (93) 38*** (135) 88*** (311)
Yes (n = 355)
Binge drinking last Saturday night
Ecstasy
*P < 0.05, **P < 0.01, ***P < 0.001 Comparisons reflect binge drinking versus no binge drinking within each group (alcohol only, cannabis and ecstasy). Note. Age comparisons made using a median comparison test. All other comparisons made with a Pearson’s χ2 test. aAUDIT score of 8+ for the past year. bIncludes cocaine, meth/amphetamine, heroin, hallucinogens and inhalants. cAt least A$67 600+ per annum before tax (27% of the sample). dLess than A$31 200 per annum before tax (30% of the sample).
Last Saturday night drug use, % (n) Stimulants Cannabis Energy drinks Alcohol use disordera, % (n) Other drugs used in the past year, % (n) Tobacco Cannabis Ecstasy Other illicit drugsb Demographics Age, median (range) Male, % (n) Not heterosexual, % (n) Married, % (n) Dependent child/ren, % (n) Completed secondary school, % (n) Technical qualification, % (n) University degree, % (n) Immigrant, % (n) Employed, % (n) Higher income groupc, % (n) Lower income groupd, % (n)
No (n = 308)
No (n = 532)
Yes (n = 380)
Binge drinking last Saturday night
Binge drinking last Saturday night Yes (n = 277)
Cannabis
Alcohol only
Table 1. Relationship between binge drinking and participant characteristics within each group
440 R. McKetin et al.
26§ (18–30) 52* (72) 26§** (36) 38 (53) 33§** (45) 66§*** (91) 25 (35) 25§** (34) 12§ (16) 64 (89) 18§ (23) 37 (46)
75§ (411) 100§ (550) 0 (0) 23 (124)§
28 (228) 0 (0) 0 (0) 3 (23) 26§ (18–30) 41§ (225) 16§ (88) 34§ (187) 20 (108) 83§ (455) 25§ (139) 37§ (205) 12§ (66) 66§ (364) 25§ (121) 34 (163)
88§** (122) 100§*** (138) 0 (0) 30§ (41)
0 (0) 0 (0) 19§ (103) 64§ (351)
0 (0) 0 (0) 14 (112) 33 (264)
27 (18–30) 50 (401) 8 (64) 43 (348) 21 (173) 89 (717) 19 (153) 50 (405) 19 (154) 72 (579) 31 (203) 30 (197)
0 (0) 100§*** (138) 29§** (40) 61§ (84)
66§ (364) 55§ (301) 33§ (183)
55 (445) 34 (277) 15 (125)
67§ (92) 57§ (79) 37§ (51)
26§ (18–30) 38§ (155) 19§ (79) 32§ (129) 17§ (67) 86 (348) 22 (90) 43§ (174) 12§ (49) 76 (309) 30 (110) 22§ (80)
81§ (329) 74§ (299) 100§ (406) 73§ (297)
0 (0) 20 (83) 26§ (104) 78§ (318)
79§ (321) 67§ (274) 46§ (185)
No stimulant use last Saturday night (n = 406)
Cannabis use last Saturday night (n = 138)
No cannabis use last Saturday night (n = 550)
25§ (18–30) 43 (39) 22§ (20) 24§ (22) 34§*** (31) 76§* (69) 23 (21) 41 (37) 12 (11) 71 (65) 30 (24) 28 (22)
89§ (81) 89§** (81) 100§ (91) 92§*** (84)
100§*** (91) 48§*** (44) 59§*** (54) 89§* (81)
95§**(86) 89§*** (81) 69§*** (63)
Stimulant use last Saturday night (n = 91)
*P < 0.05, **P < 0.01, ***P < 0.001 Cannabis users who used cannabis last Saturday night were compared to cannabis users who did not use cannabis last Saturday night. Ecstasy users who used stimulants last Saturday night were compared to ecstasy users who did not use stimulants last Saturday night. §P < 0.05, compared to the alcohol only group. Note. Age comparisons made using a median comparison test. All other comparisons made with a Pearson’s χ2 test. aAUDIT score of 8+ for the past year. bIncludes cocaine, meth/amphetamine, heroin, hallucinogens and inhalants. cAt least A$67 600+ per annum before tax (27% of the sample). dLess than A$31 200 per annum before tax (30% of the sample).
Drinking last Saturday night, % (n) Drank any alcohol Binge drank Heavy binge drinking Other drug use last Saturday night, % (n) Stimulants Cannabis Energy drinks At risk for an alcohol use disordera, %(n) Other drugs used in the past year, % (n) Tobacco Cannabis Ecstasy Other illicit drugsb Demographics Age, median (range) Male, % (n) Not heterosexual, % (n) Married, % (n) Dependent child/ren, % (n) Completed secondary school, % (n) Technical qualification, % (n) University degree, % (n) Immigrant, % (n) Employed, % (n) Higher income groupc, % (n) Lower income groupd, % (n)
Alcohol only (n = 809)
Ecstasy users
Cannabis users
Table 2. Alcohol consumption last Saturday night and participant characteristics for each group by intoxication
Stimulant use and binge drinking 441
© 2014 Australasian Professional Society on Alcohol and other Drugs
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Table 3. Predictors of binge drinking last Saturday night among ecstasy users Binge drinking last Saturday night No (n = 142)
Yes (n = 355)
7 24 16 62
23 26 38 88
3.9 1.1 3.2 4.3
80 78 72 44 34 21 32 14 82 21 38 8 66 27 31
Last Saturday night drug use (%) Stimulants Cannabis Energy drinks Alcohol use disorderb (%) Other drugs used in the past year (%) Tobacco Cannabis Other illicit drugsc Demographics >25 years of age (%) Male (%) Not heterosexual (%) Married (%) Dependent children (%) Completed secondary school (%) Technical qualification (%) University degree (%) Immigrant (%) Employed (%) Higher income groupd (%) Lower income groupe (%)
Adjusteda
Unadjusted Odds ratio (95% CI)
P value
Odds ratio (95% CI)
P value
(2.0–7.8) (0.7–1.8) (1.9–5.2) (2.7–6.9)
R E V I E W
Drug and Alcohol Review (July 2014), 33, 436–445 DOI: 10.1111/dar.12147
Recreational drug use and binge drinking: Stimulant but not cannabis intoxication is associated with excessive alcohol consumption REBECCA MCKETIN1,2, JENNY CHALMERS2, MATTHEW SUNDERLAND2 & DAVID A. BRIGHT3 1
Centre for Research on Ageing, Health and Well-Being, The Australian National University, Canberra, Australia, National Drug and Alcohol Research Centre, University of New South Wales, Sydney, Australia, 3School of Social Sciences, University of New South Wales, Sydney, Australia 2
Abstract Introduction and Aims. Binge drinking is elevated among recreational drug users, but it is not clear whether this elevation is related to intoxication with recreational drugs.We examined whether stimulant intoxication and cannabis intoxication were associated with binge drinking among young adults. Design and Methods. An online survey of 18- to 30-year-old Australians who had drunk alcohol in the past year (n = 1994) were quota sampled for: (i) past year ecstasy use (n = 497); (ii) past year cannabis (but not ecstasy) use (n = 688); and (iii) no ecstasy or cannabis use in the past year (alcohol-only group, n = 809). Binge drinking last Saturday night (five or more drinks) was compared for participants who took stimulants (ecstasy, cocaine, amphetamine or methamphetamine) or cannabis last Saturday night. Results. Ecstasy users who were intoxicated with stimulants (n = 91) were more likely to binge drink than ecstasy users who were not (n = 406) (89% vs. 67%), after adjusting for demographics, poly-drug use and intoxication with cannabis and energy drinks (adjusted odds ratio 3.1, P = 0.007), drinking a median of 20 drinks (cf. 10 drinks among other ecstasy users). Cannabis intoxication was not associated with binge drinking among cannabis users (57% vs. 55%) or ecstasy users (73% vs. 71%). Binge drinking was more common in all of these groups than in the alcohol-only group (34%). Discussion and Conclusions. Stimulant intoxication, but not cannabis intoxication, is associated with binge drinking among young adults, compounding already high rates of binge drinking among people who use these drugs. [McKetin R, Chalmers J, Sunderland M, Bright DA. Recreational drug use and binge drinking: Stimulant but not cannabis intoxication is associated with excessive alcohol consumption. Drug Alcohol Rev 2014;33:436–445] Key words: alcohol, binge, stimulants, ecstasy, cannabis.
Introduction Excessive alcohol intoxication, often referred to as heavy episodic drinking or ‘binge drinking’, accounts for the bulk of alcohol-related morbidity among young adults [1], increasing the risk of injury and some chronic diseases [2]. Definitions of binge drinking vary by country and have changed over time, but consensus currently rests at drinking in excess of around four to five drinks on a single occasion [3]. This is the lower bound at which harms are significantly increased [4,5]; however, binge drinking often involves much higher levels of alcohol consumption [6–8], especially on
Saturday evenings [9]. These more excessive levels of consumption disproportionately increase the risk of violence-related injury [10]. Research on heavy episodic drinking rarely considers the impact of concurrent illicit drug use [11].This is an oversight given the increasingly common practice of taking of recreational drugs, particularly illicit stimulant drugs, during heavy drinking sessions both in Australia [12,13] and elsewhere [14–16].This trend is thought to reflect the mainstreaming of ecstasy use [17], increased availability of cheap ecstasy (cf. expensive alcohol) and a culture of poly-pharmacy among hedonistic youngsters who seek out ways to maximise pleasure from their
Rebecca McKetin PhD, Fellow, Jenny Chalmers PhD, Senior Research Fellow, Matthew Sunderland PhD, NHMRC Early Career Research Fellow, David A. Bright PhD, Senior Lecturer. Correspondence to Dr Rebecca McKetin, Centre for Research on Ageing, Health and Well-Being, Building 63, Eggleston Road, The Australian National University, Canberra, ACT 0200, Australia. Tel: +2 612 5840; Fax: +61 2 612 51558; E-mail: [email protected] Received 17 December 2013; accepted for publication 31 March 2014. © 2014 Australasian Professional Society on Alcohol and other Drugs
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nights out [14]. In Australia, the use of ecstasy in the recreational drug scene has been supplemented with the more potent stimulants: 61% of regular ecstasy users report recent use of methamphetamine use and 40% report recent use of cocaine, in addition to the vast majority of recreational drug users smoking cannabis and drinking alcohol [18]. Intoxication with stimulants may facilitate alcohol consumption: stimulants complement the effects of alcohol, producing a longer lasting euphoria than either drug taken alone [19], offset the sedating effects of alcohol intoxication [19,20], reduce the unpleasant effects of stimulants (e.g. anxiety and agitation) [21,22] and they facilitate the desire to keep drinking alcohol [23–26]. In contrast, although cannabis use is also popular among young adults, it appears to substitute for alcohol, rather than complementing the effects of alcohol, with greater cannabis being associated with less alcohol use and vice versa [27,28].This is thought to be due to the similar pharmacological effects of alcohol and cannabis [11], in that cannabis and alcohol have an additive effect on sedation, fatigue and impairments in functioning [29–32]. Despite the increased popularity of combining recreational stimulant drugs with alcohol, no research has examined whether this practice is related to heavier drinking. Although elevated rates of binge drinking have been found among recreational illicit drug users (a relationship which appears to be generic to various types of drug use [33,34]), this research compares rates of drinking and drug use over a long time-frame (e.g. past year) and therefore it is not clear whether binge drinking co-occurs with drug intoxication (i.e. intoxication on alcohol and other drugs is complementary) or whether the two events occurred on separate occasions. The fact that the same people take drugs and drink heavily may simply reflect common risk factors for various substance use disorders [35]. Event-based research, whereby patterns of behaviour are examined within a single event or at a single timepoint, has been recently adopted to better understand factors associated with heavy drinking occasions [9].We used an event-based approach to examine whether intoxication with common recreational drugs (stimulants and cannabis) was related to concurrent heavier drinking.To do this, we compared alcohol consumption for ecstasy users who had taken stimulants last Saturday night (ecstasy, methamphetamine or cocaine) with ecstasy users who had not taken stimulants last Saturday night. Ecstasy users were chosen as a sentinel group of stimulant users because of the popularity of ecstasy use among young adults.We used the same approach to examine the relationship between cannabis intoxication and drinking, comparing alcohol consumption last Saturday night among a sample of cannabis users by
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whether or not they had smoked cannabis last Saturday night. Based on their pharmacological interaction with alcohol, we expected that stimulant intoxication, but not cannabis intoxication, would co-occur with heavier drinking. We also compared alcohol consumption in these groups with that seen in a sample of young adults who did not use ecstasy or cannabis, to gauge their relative levels of drinking. Methods Procedure Data were collected as part of a self-completed online survey about alcohol pricing that was carried out between November 2011 and March 2012 and which took approximately 20 min to complete. The survey was implemented by a commercial company (Pureprofile.com™: http://www.pureprofile.com) that reimbursed participants approximately A$4 per survey completed. Ethics approval was provided by the University of New South Wales Human Research Ethics Committee. Sample Participants were recruited through the Pureprofile Internet market research panel that included 107 604 Australians who could choose to participate in the survey if they were eligible. Eligible participants were aged 18–30 years and had used alcohol in the past year. Within these eligibility criteria, quota sampling was used to recruit equal numbers of men and women who had either: (i) used ecstasy in the past year (ecstasy users); (ii) used cannabis but not ecstasy in the past year (cannabis users); or (iii) who had not used either cannabis or ecstasy in the past year (alcohol only). Recruitment was discontinued when the number of completed surveys reached 400 for men and 400 for women in each of these three categories, or when the number of new recruits fell to below five per week. Participants who had started the survey at the time that recruitment was closed were included in the sample, resulting in over 400 participants in some quotas. In total, 2013 participants were recruited, with the quota for male ecstasy users, female ecstasy users and male cannabis users not being filled (see Supporting Information Appendix S1 for details). Participants from the cannabis and alcohol-only quota were excluded if they took stimulants last Saturday night (19 had taken methamphetamine or cocaine, see Supporting Information Appendix S1 for details) to ensure that these comparison groups would not be contaminated with the effect of stimulant intoxication. The final sample (n = 1994) included 497 ecstasy users © 2014 Australasian Professional Society on Alcohol and other Drugs
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(194 men and 303 women), 688 cannabis users (297 male and 391 female) and 809 in the alcohol-only group (401 male and 408 female). Representativeness of the sample To assess bias in our sample we compared each quota with the corresponding sample drawn from a representative survey of 26 648 Australians aged 12 years or older (the 2010 Australian National Drug Strategy Household Survey) who were surveyed via either a drop-and-collect survey or a computer-assisted telephone interview [36]. Compared with the National Drug Strategy Household Survey sample, our sample tended to be slightly older, better educated, receive more income, more likely to be married or de facto, more likely to smoke tobacco and more likely to have a history of illicit drug use (see Supporting Information Appendix S2 for details). Measures Alcohol consumption last Saturday night. The main outcome was binge drinking last Saturday night, defined as having consumed five or more drinks last Saturday night. A drink was defined as 10 g of alcohol reflecting Australian definitions of a standard drink [37]. Last Saturday night was defined as the 12-h period from 6pm on Saturday to 6am on Sunday. Questions on alcohol consumption were modified from the Australian National Drug Strategy Household Survey [36] and assessed the number of alcoholic drinks by container type (e.g. bottles, cans and glasses) for each type of beverage (beer, cider, wine, spirits, premixed spirits, premixed alcohol energy drinks, fortified wine and other types of alcohol).The total volume of alcohol consumed (grams) was calculated using the estimated volume for each container type and an estimated alcohol content for each beverage type (see Supporting Information Appendix S3 for details). Drug intoxication last Saturday night. The main predictor variables were: (i) intoxication with stimulants last Saturday night; and (ii) intoxication with cannabis last Saturday night. As done for alcohol consumption, Saturday night was defined as the 12-h period from 6pm on Saturday to 6am on Sunday. Stimulant use last Saturday night was defined as having taken ecstasy, cocaine or meth/amphetamine, determined by asking participants which of the following drugs they had used last Saturday night (yes/no): (i) ecstasy (ETC, E, Ecci, Adam, MDMA, MDDA, MDEA, Eve, etc.); (ii) cocaine (coke, crack, etc.), and (iii) methamphetamine or amphetamine (speed, meth, base, crystal, ice, amphetamine, etc.). Of the participants in the ecstasy © 2014 Australasian Professional Society on Alcohol and other Drugs
using group who had taken stimulants last Saturday night (n = 91), 29 had used ecstasy, nine had used cocaine, 17 had used meth/amphetamine, 10 had used ecstasy and meth/amphetamine, six had used ecstasy and cocaine, one had used methamphetamine and cocaine and 19 had used all three drugs. Cannabis use was defined as having reported ‘marijuana/cannabis’ use last Saturday night (yes/no). Covariates. Other measures included the Alcohol Use Disorders Identification Test (AUDIT), any use of other drugs used in the past year by drug type (heroin, cocaine, methamphetamine, hallucinogens, inhalants and tobacco) and demographics (sex, gender orientation, age, country of birth, income category, employment status, marital status, living with dependent children and highest level of education completed). A score of 8 or more on the AUDIT was used to identify participants at risk of an alcohol use disorder [38]. Information was also collected on the consumption of energy drinks, either premixed with alcohol or alone, last Saturday night, and this was coded as a binary variable reflecting the consumption of any energy drinks last Saturday night. Design To understand whether binge drinking among ecstasy users was related to stimulant intoxication we compared binge drinking for ecstasy users who had taken stimulants (n = 91) with those who had not taken stimulants (n = 406) last Saturday night. Within the ecstasy-using group, we also examined whether cannabis use last Saturday night (n = 127) was related to binge drinking. To determine whether cannabis intoxication was associated with binge drinking, we compared binge drinking for cannabis users who had smoked cannabis on the previous Saturday night (n = 138) with those who had not (n = 550). Finally, we compared binge drinking in each of these groups with the alcohol-only group (n = 809) to gauge their relative alcohol consumption. Analysis Logistic regression was used to compare groups on binge drinking and adjust for covariates. The outcome variable in these analyses was binge drinking last Saturday night (unless otherwise stated). The first analysis was conducted within the ecstasy user group, and the predictor variable was intoxication with stimulants last Saturday night (yes/no). The second analysis was conducted within the cannabis user group, and the predictor variable was intoxication with cannabis last Saturday night (yes/no). The remaining logistic
Stimulant use and binge drinking
regression analyses compared binge drinking in each of these four groups with the alcohol-only group. Missing data were assumed to be missing at random and excluded. All tests were two sided with significance set at P < 0.05. Data were analysed using stata SE Version 11.2 [39]. Results Characteristics of the sample Participants had a median age of 26 years (range 18–30 years), 45% were male, 70% were employed and the majority were born in Australia (85%) and spoke English as their main language (93%). Only 2% were from an aboriginal or Torres Strait Islander background. The majority had never been married (61%), identified as heterosexual (86%), had completed high school (84%) and had a tertiary qualification (22% had a trade qualification or diploma and 43% had a university degree). Over half (55%) of the sample were at risk of an alcohol use disorder (i.e. AUDIT score of 8+), 59% smoked tobacco and 29% had used other illicit drugs (i.e. besides cannabis and ecstasy) in the past year. Energy drinks were consumed by 21% of the sample last Saturday night, most of whom drank alcohol (88%). Drinking last Saturday night Sixty-three per cent of the sample drank alcohol last Saturday night, with three-quarters of these respondents, or 48% of the entire sample, reporting binge drinking last Saturday night. The characteristics of participants who binge drank is shown in Table 1 for each of the three groups. From Table 1, it can be seen that binge drinking was more common among participants who had an alcohol use disorder and who had consumed energy drinks last Saturday night, and it was less common among people on a low income or who were not employed. Binge drinking was more common among men than women, but this difference was not statistically significant for ecstasy users. In the alcoholonly group, there was a higher proportion of tobacco smokers who binge drank, but this was not true of either the ecstasy users or the cannabis users, all of whom had comparatively high rates of tobacco smoking. There was also a slightly high prevalence of binge drinking last Saturday night among ecstasy users who had dependent children, although only a minority of the sample fell into this category. Binge drinking among ecstasy users Ecstasy users who had taken stimulants last Saturday night were 3.9 times more likely to binge drink than
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those who had not taken ecstasy last Saturday night (89% vs. 67%; Table 2). After adjusting for demographic variables, risk of an alcohol use disorder, other illicit drug use in the past year, and cannabis and energy drink consumption last Saturday night, ecstasy users who took stimulants last Saturday night were still three times as likely to binge drink compared with their ecstasy-using peers who did not take stimulants last Saturday night (Table 3). Cannabis use last Saturday night was not significantly related to binge drinking among ecstasy users (73% vs. 71%; Table 2). Ecstasy users drank a median of 12 drinks last Saturday night, with those who took stimulants drinking a median of 20 drinks (cf. 10 drinks among ecstasy users who did not take stimulants last Saturday night). To investigate this excessive level of drinking further, we undertook a post-hoc analysis of participants who consumed 12 or more standard drinks last Saturday night (which we term ‘excessive binge drinking’). Excessive binge drinking was 2.7 times more likely among ecstasy users who took stimulants last Saturday night compared with those who did not [95% confidence interval (CI) 1.7–4.4, P < 0.001], with 69% binge drinking excessively (cf. 46% among ecstasy users who did not take stimulants last Saturday night). This effect remained significant after adjusting for all covariates [adjusted odds ratio (OR) 2.0, 95% CI 1.1–3.6, P = 0.03]. There was no association between cannabis intoxication and excessive binge drinking (adjusted OR 1.2, 95% CI 0.7–2.0, P = 0.608). Details of this analysis can be found in Supporting Information Appendix S4. Binge drinking among cannabis users Binge drinking last Saturday night was no more common among cannabis users who had smoked cannabis last Saturday night than those who had not (57% vs. 55%, OR 1.1, 95% CI 0.8–1.6, P = 0.595). This effect remained non-significant after adjusting for demographic variables, being at risk of an alcohol use disorder and other illicit drug use (adjusted OR 1.3, 95% CI 0.9–2.1, P = 0.206). Comparison with the alcohol only group Both ecstasy and cannabis users were more likely to binge drink, and to binge drink excessively, relative to the alcohol only group (Figure 1). After adjusting for covariates (demographics, tobacco use and energy drink consumption last Saturday night) the odds of binge drinking was 7.5 times greater for ecstasy users who had taken stimulants last Saturday night than for the alcohol only group (95% CI 2.2–25.7, P = 0.010). It was only twice as high for ecstasy users who had not taken stimulants last Saturday (adjusted OR 2.0, 95% © 2014 Australasian Professional Society on Alcohol and other Drugs
© 2014 Australasian Professional Society on Alcohol and other Drugs
0 (0) 0 (0) 26*** (72) 62*** (171) 38*** (105) 0 (0) 0 (0) 4 (11) 27 (18–30) 57** (158) 5 (15) 43 (118) 22 (61) 88 (244) 21 (58) 49 (137) 18 (50) 76* (211) 36* (85) 22** (52)
0 (0) 0 (0) 8 (40) 17 (93) 23 (123) 0 (0) 0 (0) 2 (12) 27 (18–30) 46 (243) 9 (49) 43 (230) 21 (112) 89 (473) 18 (95) 50 (268) 20 (104) 69 (368) 27 (118) 34 (145)
25 (18–30) 37 (113) 17 (52) 35 (109) 25 (77) 77 (236) 23 (72) 31 (95) 12 (37) 59 (183) 20 (53) 41 (109)
76 (234) 100 (308) 0 (0) 24 (75)
0 (0) 19 (59) 9 (29) 44 (134)
26 (18–30) 48** (184) 19 (72) 34 (131) 20 (76) 82 (310) 27 (102) 38 (144) 12 (45) 71** (270) 27 (91) 29** (100)
79 (299) 100 (380) 0 (0) 24 (90)
0 (0) 21 (79) 30*** (114) 79*** (301)
25 (18–30) 34 (48) 21 (30) 32 (46) 14 (20) 82 (117) 21 (30) 38 (54) 8 (11) 66 (94) 27 (33) 31 (37)
80 (114) 78 (111) 100 (142) 72 (102)
7 (0) 24 (34) 16 (23) 62 (88)
No (n = 142)
26 (18–30) 41 (146) 19 (69) 30 (105) 22* (78) 85 (300) 23 (81) 44 (157) 14 (49) 79** (280) 31 (101) 20* (65)
83 (296) 76 (269) 100 (355) 79 (279)
23*** (81) 26 (93) 38*** (135) 88*** (311)
Yes (n = 355)
Binge drinking last Saturday night
Ecstasy
*P < 0.05, **P < 0.01, ***P < 0.001 Comparisons reflect binge drinking versus no binge drinking within each group (alcohol only, cannabis and ecstasy). Note. Age comparisons made using a median comparison test. All other comparisons made with a Pearson’s χ2 test. aAUDIT score of 8+ for the past year. bIncludes cocaine, meth/amphetamine, heroin, hallucinogens and inhalants. cAt least A$67 600+ per annum before tax (27% of the sample). dLess than A$31 200 per annum before tax (30% of the sample).
Last Saturday night drug use, % (n) Stimulants Cannabis Energy drinks Alcohol use disordera, % (n) Other drugs used in the past year, % (n) Tobacco Cannabis Ecstasy Other illicit drugsb Demographics Age, median (range) Male, % (n) Not heterosexual, % (n) Married, % (n) Dependent child/ren, % (n) Completed secondary school, % (n) Technical qualification, % (n) University degree, % (n) Immigrant, % (n) Employed, % (n) Higher income groupc, % (n) Lower income groupd, % (n)
No (n = 308)
No (n = 532)
Yes (n = 380)
Binge drinking last Saturday night
Binge drinking last Saturday night Yes (n = 277)
Cannabis
Alcohol only
Table 1. Relationship between binge drinking and participant characteristics within each group
440 R. McKetin et al.
26§ (18–30) 52* (72) 26§** (36) 38 (53) 33§** (45) 66§*** (91) 25 (35) 25§** (34) 12§ (16) 64 (89) 18§ (23) 37 (46)
75§ (411) 100§ (550) 0 (0) 23 (124)§
28 (228) 0 (0) 0 (0) 3 (23) 26§ (18–30) 41§ (225) 16§ (88) 34§ (187) 20 (108) 83§ (455) 25§ (139) 37§ (205) 12§ (66) 66§ (364) 25§ (121) 34 (163)
88§** (122) 100§*** (138) 0 (0) 30§ (41)
0 (0) 0 (0) 19§ (103) 64§ (351)
0 (0) 0 (0) 14 (112) 33 (264)
27 (18–30) 50 (401) 8 (64) 43 (348) 21 (173) 89 (717) 19 (153) 50 (405) 19 (154) 72 (579) 31 (203) 30 (197)
0 (0) 100§*** (138) 29§** (40) 61§ (84)
66§ (364) 55§ (301) 33§ (183)
55 (445) 34 (277) 15 (125)
67§ (92) 57§ (79) 37§ (51)
26§ (18–30) 38§ (155) 19§ (79) 32§ (129) 17§ (67) 86 (348) 22 (90) 43§ (174) 12§ (49) 76 (309) 30 (110) 22§ (80)
81§ (329) 74§ (299) 100§ (406) 73§ (297)
0 (0) 20 (83) 26§ (104) 78§ (318)
79§ (321) 67§ (274) 46§ (185)
No stimulant use last Saturday night (n = 406)
Cannabis use last Saturday night (n = 138)
No cannabis use last Saturday night (n = 550)
25§ (18–30) 43 (39) 22§ (20) 24§ (22) 34§*** (31) 76§* (69) 23 (21) 41 (37) 12 (11) 71 (65) 30 (24) 28 (22)
89§ (81) 89§** (81) 100§ (91) 92§*** (84)
100§*** (91) 48§*** (44) 59§*** (54) 89§* (81)
95§**(86) 89§*** (81) 69§*** (63)
Stimulant use last Saturday night (n = 91)
*P < 0.05, **P < 0.01, ***P < 0.001 Cannabis users who used cannabis last Saturday night were compared to cannabis users who did not use cannabis last Saturday night. Ecstasy users who used stimulants last Saturday night were compared to ecstasy users who did not use stimulants last Saturday night. §P < 0.05, compared to the alcohol only group. Note. Age comparisons made using a median comparison test. All other comparisons made with a Pearson’s χ2 test. aAUDIT score of 8+ for the past year. bIncludes cocaine, meth/amphetamine, heroin, hallucinogens and inhalants. cAt least A$67 600+ per annum before tax (27% of the sample). dLess than A$31 200 per annum before tax (30% of the sample).
Drinking last Saturday night, % (n) Drank any alcohol Binge drank Heavy binge drinking Other drug use last Saturday night, % (n) Stimulants Cannabis Energy drinks At risk for an alcohol use disordera, %(n) Other drugs used in the past year, % (n) Tobacco Cannabis Ecstasy Other illicit drugsb Demographics Age, median (range) Male, % (n) Not heterosexual, % (n) Married, % (n) Dependent child/ren, % (n) Completed secondary school, % (n) Technical qualification, % (n) University degree, % (n) Immigrant, % (n) Employed, % (n) Higher income groupc, % (n) Lower income groupd, % (n)
Alcohol only (n = 809)
Ecstasy users
Cannabis users
Table 2. Alcohol consumption last Saturday night and participant characteristics for each group by intoxication
Stimulant use and binge drinking 441
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Table 3. Predictors of binge drinking last Saturday night among ecstasy users Binge drinking last Saturday night No (n = 142)
Yes (n = 355)
7 24 16 62
23 26 38 88
3.9 1.1 3.2 4.3
80 78 72 44 34 21 32 14 82 21 38 8 66 27 31
Last Saturday night drug use (%) Stimulants Cannabis Energy drinks Alcohol use disorderb (%) Other drugs used in the past year (%) Tobacco Cannabis Other illicit drugsc Demographics >25 years of age (%) Male (%) Not heterosexual (%) Married (%) Dependent children (%) Completed secondary school (%) Technical qualification (%) University degree (%) Immigrant (%) Employed (%) Higher income groupd (%) Lower income groupe (%)
Adjusteda
Unadjusted Odds ratio (95% CI)
P value
Odds ratio (95% CI)
P value
(2.0–7.8) (0.7–1.8) (1.9–5.2) (2.7–6.9)
