Consequences of concurrent and simultaneous amphetamine-type stimulant and alcohol use among young adults: hazardous drinking, antisocial behaviour, and contact with police

Abstract

Background: Amphetamine-type stimulants (ATS) include ecstasy (3,4-methylenedioxymethamphetamine [MDMA]) and methamphetamine and are the second most widely used illicit drugs in Australia, following cannabis. ATS use is most common among young adults aged 20-29 years, who often use these substances recreationally in leisure settings (e.g., nightclubs, pubs, bars, raves, music festivals, and parties). Prior research indicates that alcohol and illicit stimulants, such as ATS, are often combined in nightlife entertainment districts in the context of a big night out. The combined use of these substances represents an emerging area of concern, as evidence suggests that their combined use may result in greater harms than their separate use, including increased neurotoxicity, hazardous alcohol consumption, and aggression. However, despite the prevalence of ATS use among young adults and its use in settings in which alcohol is also prevalent, knowledge of community patterns of combined alcohol and ATS use is limited and research examining the potential consequences of combined use is scarce.Objectives: This thesis examines consequences of concurrent and simultaneous alcohol and ATS use among a population-based sample of young adult ATS users, focusing on: hazardous alcohol consumption, aggression, and contact with police.Methods: Data for this study are drawn from the Natural History Study of Drug Use (NHSDU), a prospective longitudinal study of drug use among a population-based sample of young adult ATS users and non-users in South-East Queensland, Australia. A brief drug use screening questionnaire was mailed to 12,079 young adults (aged 19-23 years) randomly selected from the Brisbane and Gold Coast electoral rolls, with a response rate of 49.9%. From this screening data, a sampling frame was developed from which an ATS-user group (used ecstasy or methamphetamine ≥3 times within the last 12 months, n=352) and a comparison group of non-users (random selection of the young adults who had never used ecstasy or methamphetamine at the time of screening, n=204) were recruited.Key findings: Study findings showed that alcohol use was prevalent among these young adult ATS users and was often used in combination with ATS. At the study baseline, 96.5% of ATS users had consumed alcohol in the last month and 92.9% of ecstasy users and 80.7% of methamphetamine users usually consumed alcohol during ecstasy and methamphetamine use episodes, respectively. Heavy episodic drinking was also common among ATS users, with 56.9% of female ATS users and 77.9% of male ATS users usually consuming >4 standard drinks on days of drinking at baseline. Findings indicated ecstasy use may play a role in the high rates of heavy episodic drinking among these young adults, with concurrent ecstasy use – though not concurrent methamphetamine use – associated with these hazardous patterns of alcohol consumption. While not associated with hazardous drinking, combined alcohol and methamphetamine use was shown to play a role in aggressive behaviour. Patterns of simultaneous alcohol and methamphetamine use were associated with both methamphetamine-attributed subjective feelings of aggression or hostility and acts of verbal and physical aggression while under the influence of illicit drugs. Lastly, for these young adults, engagement in illicit drug use, hazardous drinking, and antisocial behaviour likely puts them at an increased risk of contact with police. Findings showed that ATS users were more likely than non-using young adults to have experienced substance-related police contact and were more likely to have experienced more intensive police contact. Additionally, these findings suggest that police contact may impact on both substance use behaviours and perceptions of police and policing.Conclusions: This thesis extends current knowledge of community patterns of combined alcohol and ATS use and the potential consequences for young adults. Results highlighted that combined alcohol and ATS use is ubiquitous among these young adults. Further, this research indicates that the combined use of alcohol and ATS is associated with a number of concerning outcomes, including hazardous alcohol consumption, aggression, and contact with police, which have both health and social implications. Specifically, these findings suggest that young adult ATS users may be a key target group for alcohol interventions. Further, the policy challenges of alcohol, ATS use, and aggression among young adults need to be better considered in relation to the interlinking of these issues.