'High' risk? A systematic review of the acute outcomes of mixing alcohol with energy drinks

Alcohol mixed with energy drinks and aggressive behaviors in adolescents and young adults: A systematic review

PURPOSE

Consuming alcohol mixed with energy drinks (AmED) is a high-risk drinking practice. This systematic review examines how AmED use contributes to aggression (physical and sexual), in what role(s) (perpetrator and/or victim), in adolescents and young adult drinkers (age 25 and younger).

METHODS

Computer assisted search identified 844 studies conducted prior to March 2023; of them 17 met inclusion criteria.

RESULTS

AmED use was significantly associated with aggressive behaviors. Between-subject studies suggests that AmED consumers have higher rates of perpetration (physical fights, bullying) and victimization compared to peers who only drink alcohol; however, within-subject studies of AmED users find no difference in physical aggression by drinking event (AmED vs. occasions where consumer drinks alcohol only). Similarly, AmED use was a risk factor for sexually aggressive behaviors (e.g., unwanted contact) and victimization.

CONCLUSIONS

AmED use is a significant risk factor both victimization and perpetration of violent acts. Differences in within- versus between-study findings suggests that risk is associated with use of AmED, and not event level differences in drinking occasions among AmED users. Findings highlight the relative paucity of studies examining victimization and sexual violence and the need for future studies to incorporate more diverse samples and methodologies to better understand patterns of AmED use, perpetration, and victimization.

Alcohol Versus Combined Alcohol and Energy Drinks Consumption: risk behaviours and consumption patterns among European students

INTRODUCTION

Recent research found that mixing energy drinks with alcohol (AmED) could be more risky than drinking alcohol alone. Our aim was to compare rates of risk behaviours in consumers AmED versus exclusive alcohol drinkers, matching them based on their drinking frequency.

METHODS

Data about sixteen-year-old students who reported the number occasions on which they had drunk AmED or alcohol only in the preceding 12 months (n = 32,848) were drawn from the 2019 ESPAD study. After matching for consumption frequency, the sample consisted of 22,370 students (11,185 AmED consumers and 11,185 exclusive alcohol drinkers). Key predictors comprised substance use, other individual risk behaviours and family characteristics (parental regulation, monitoring and caring).

RESULTS

The multivariate analysis showed significantly higher odds of being AmED consumers compared to exclusive alcohol drinkers in the majority of the investigated risk behaviours, including: daily tobacco smoking, illicit drug use, heavy episodic drinking, truancy at school, engaging in physical fights and serious arguments, having troubles with the police and having unprotected sexual intercourse. Instead, lower odds were found for reporting high parents' educational level, medium and low family economic status, perceived possibility to freely talk about problems to family members, spending free time reading books or other hobbies.

CONCLUSIONS

Our study shows that, given the same consumption frequency in the past year, AmED consumers typically reported higher associations with risk-taking behaviours compared to exclusive alcohol drinkers. These findings advance past research that failed to control for the frequency of AmED use versus exclusive alcohol consumption.

Preloading, exit intoxication related to energy drink usage, and gender differences within night-time entertainment districts for young people

BACKGROUND

Governments frequently introduce legislation to reduce drunkenness and violence in night-time entertainment districts (NEDs). However, there is no study which has looked at inebriation of a large sample of young people exiting a NED. We investigated Breath Approximated Blood Alcohol Concentration (BrAC; grams per decilitre, g/dl) levels as people left Brisbane (Australia) NEDs and measured the effects of preloading, energy drink usage, time of night and gender differences on exit intoxication.

METHODS

We systematically assessed patrons between November 2015 to March 2019 by administering surveys and breathalysing them as they exited the NEDs. We then analysed only those under the age of 26 years old (n = 3,211) as there was a natural break in the data on energy drink usage for those aged over 25 years old.

FINDINGS

This study found that young drinkers leave the NED with an average BrAC of 0.094 g/dl. Consistent with hypotheses, the exit BrAC was significantly and meaningfully higher in preloaders (medium effect size). These preloaders also came into the NEDs later but stayed for the same length of time as non-preloaders. BrAC levels did not significantly differ for those who did or did not use energy drinks during the night. As predicted, gender was not associated with a meaningful difference in alcohol intoxication and consumption. The time of night that patrons were interviewed was positively associated with inebriation levels, however, this association was small (r ≈ 0.1).

DISCUSSION

With preloading being such a strong predictor for end of night intoxication, and length of time spent in the NED equal between those who do or do not preload, we suggest that to have people less inebriated, they should be encouraged into the NED earlier rather than focusing on their leaving time.

Caffeine content of energy drinks marketed in Brazil

Energy drinks represent a multibillionaire industry that has been growing continuously worldwide. These drinks are especially consumed by young people, athletes, and military personnel due to their claimed "boost" effects. However, there have been concerns about their consumption since incompatibilities regarding the accuracy of the declared caffeine content of these drinks have been reported. Therefore, in this study we have developed a fast and simple method to quantify caffeine in energy drinks. Sample preparation consisted of a dilute-and-shoot process, and analyses were performed by gas-chromatography with nitrogen-phosphorus detector (GC-NPD). The method was applied to quantify caffeine in 37 energy drinks marketed in Brazil. Compared to the labeled caffeine content, 84% of the tested drinks presented caffeine levels in accordance with the specifications. The determined caffeine concentrations ranged from 10 to 67 mg/100 mL, with an average value of 31 mg/100 mL. According to the recommended serving size, no drinks exceeded the safe caffeine daily intake for the general population (400 mg). These findings are more favorable than the results of similar studies. Nevertheless, to avoid caffeine intoxication, energy drink consumers should be aware of three aspects. First, they need to avoid consuming multiple serving doses in short periods of time. Additionally, some energy drinks are labeled as "nutritional supplements", so they may present much more caffeine than similar products commonly regulated as beverages. Finally, despite the growing interest in energy drinks, their consumption by children and early adolescents is being discouraged by the health authorities.

Risky behaviors, substance use, and other lifestyle correlates of energy drink consumption in children and adolescents: a systematic review

Increasing concerns have been raised on the health-related risks connected with energy drink (ED) consumption in children and adolescents, with high acute or chronic consumers exceeding 10% in either age group in Europe in 2011. Preliminary evidence has suggested a common pattern of ED and substance use, especially alcohol. Additional evidence has been accumulating very fast; in addition, other lifestyle and risky behaviors may contribute to shed light on the complex interplay of factors involved in ED consumption. We have undertaken a comprehensive systematic review of the evidence on psychosocial correlates of ED consumption in 0-18 years subjects, as published up to April 1, 2021, in MEDLINE/PubMed, PsycINFO, and Cochrane Reviews and Central Register of Controlled Trials, which allowed to select 104 original articles. Only ~ 10% of the papers provided results based on longitudinal analyses. A common pattern of ED consumption and polysubstance use, including alcohol, tobacco, and soft and hard drugs, was still confirmed in adolescents; violent and risky behaviors were also related to a higher ED consumption. In addition, frequent ED consumers are more likely to have bad dietary habits, including consumption of sugar-sweetened beverages and junk foods. A generally inconclusive evidence was found for sport/physical activities, although sedentary behaviors were generally related to ED consumption.

CONCLUSIONS

Frequent ED consumption might be a screening indicator to identify students at risk of substance use or other risky/problem behaviors; enquiring about an adolescent's recent ED consumption could create opportunities for early intervention/prevention by informed pediatricians.

WHAT IS KNOWN

• Substances, especially alcohol, are associated with energy drinks in most cross-sectional studies.

WHAT IS NEW

• Violent behaviors are associated with energy drink consumption, in the absence of longitudinal studies; problematic use of internet/videogames deserves further investigation; unhealthy dietary patterns are related to energy drinks; evidence on physical activity is inconclusive, but sedentary behaviors are related to energy drinks.

An on-premise study to investigate the effects of mixing alcohol with caffeinated beverages

OBJECTIVE

The purpose of this on-premise study was to determine if mixing alcohol with caffeinated mixers had an impact on objective and subjective intoxication.

METHODS

The study was conducted across eight drinking occasions in the City of Bristol, UK. Participants (N = 1041) were recruited outside popular night-time entertainment venues and interviewed regarding their alcohol consumption for that particular evening, including whether or not they had consumed caffeinated beverages with alcohol. Subjective intoxication was rated on an 11-point scale and objective intoxication determined with a breath alcohol test. Depending on their consumption on the night of the interview, participants also reported whether they consumed alcohol mixed with caffeinated mixers or alcohol-only on other consumption occasions.

RESULTS

Between-subjects analyses found that alcohol-caffeine consumers consumed more alcohol and had higher objective and subjective intoxication than those who consumed alcohol-only. These results remained significant regardless of whether or not they mixed alcohol with caffeinated mixers or consumed alcohol-only on the night of the interview. Within-subject analyses revealed that alcohol-caffeine consumers drank the same or less alcohol on alcohol-caffeine occasions compared to alcohol-only occasions.

CONCLUSIONS

These findings provide support that alcohol-caffeine use does not increase overall alcohol consumption, and may be one manifestation of a high risk-taking personality.

Effects of the psychoactive compounds in green tea on risky decision-making

Epigallocatechin-3-gallate (EGCG) and caffeine are the two primary compounds found in green tea. While EGCG has anxiolytic and anti-inflammatory effects, its acute effects on cognition are not well understood. Furthermore, despite widespread green tea consumption, little is known about how EGCG and caffeine co-administration impacts behavior. Here, we investigated the effects of multiple doses of either EGCG or caffeine on a rat model of risk-taking. This was assessed using the risky decision-making task (RDT), in which rats choose between a small, well-tolerated reward and a large reward with escalating risk of mild footshock. Rats were tested in RDT after acute systemic administration of EGCG, caffeine or joint EGCG and caffeine. EGCG caused a dose-dependent reduction in risk-taking without affecting reward discrimination or task engagement. Caffeine did not impact risk-taking, but elevated locomotor activity and reduced task engagement at high doses. Finally, exposure to both EGCG and caffeine had no effect on risk-taking, suggesting that low-dose caffeine is sufficient to mask the risk-aversion caused by EGCG. These data suggest EGCG as a potential therapeutic treatment for psychological disorders that induce compulsive risky decision-making.

A Comparison Between Ecological Momentary Assessment and the Adapted-Quick Drinking Screen: Alcohol Mixed With Energy Drinks

Aims

To compare alcohol consumption and risk-taking behaviours on alcohol mixed with energy drink (AMED) and alcohol-only (AO) drinking occasions collected via ecological momentary assessment (EMA) versus retrospective survey methods (adapted-Quick Drinking Screen: a-QDS).

Methods

Completing participants were 52 university students who reported AMED consumption during the 30-day data collection period. Alcohol consumption and risk-taking behaviours were captured for recreational AMED and AO consumption occasions using a smartphone-based app across 30 days. Data were aggregated for comparison with the a-QDS conducted at the end of data collection.

Results

Irrespective of data collection method, alcohol was consumed more frequently and at higher quantities on the heaviest drinking occasions when consumed alone compared with when it was mixed with energy drinks. Consistent with this finding, more risk-taking behaviours were experienced on AO occasions compared with AMED occasions. Compared with the a-QDS, the quantity of alcohol consumed on the average and heaviest drinking occasion was significantly higher when reported via EMA. This was consistent across both AO and AMED drinking occasions.

Conclusion

EMA provides a more valid measure of consumption quantity compared with retrospective recall, which was susceptible to under-reporting, although this was not differentially affected across consumption occasions. In line with previous research, this study demonstrated that mixing alcohol with energy drinks does not increase alcohol consumption or risk-taking behaviours.

Neurochemical and Behavioral Consequences of Ethanol and/or Caffeine Exposure: Effects in Zebrafish and Rodents

Zebrafish are increasingly being utilized to model the behavioral and neurochemical effects of pharmaceuticals and, more recently, pharmaceutical interactions. Zebrafish models of stress establish that both caffeine and ethanol influence anxiety, though few studies have implemented co-administration to assess the interaction of anxiety and reward-seeking. Caffeine exposure in zebrafish is teratogenic, causing developmental abnormalities in the cardiovascular, neuromuscular, and nervous systems of embryos and larvae. Ethanol is also a teratogen and, as an anxiolytic substance, may be able to offset the anxiogenic effects of caffeine. Co-exposure to caffeine and alcohol impacts neuroanatomy and behavior in adolescent animal models, suggesting stimulant substances may moderate the impact of alcohol on neural circuit development. Here, we review the literature describing neuropharmacological and behavioral consequences of caffeine and/or alcohol exposure in the zebrafish model, focusing on neurochemistry, locomotor effects, and behavioral assessments of stress/anxiety as reported in adolescent/juvenile and adult animals. The purpose of this review is twofold: (1) describe the work in zebrafish documenting the effects of ethanol and/or caffeine exposure and (2) compare these zebrafish studies with comparable experiments in rodents. We focus on specific neurochemical pathways (dopamine, serotonin, adenosine, GABA, adenosine), anxiety-type behaviors (assessed with novel tank, thigmotaxis, shoaling), and locomotor changes resulting from both individual and co-exposure. We compare findings in zebrafish with those in rodent models, revealing similarities across species and identifying conservation of mechanisms that potentially reinforce co-addiction.

Interaction of Energy Drinks with Prescription Medication and Drugs of Abuse

In recent years, the consumption of energy drinks (EDs) has become increasingly popular, especially among adolescents. Caffeine, a psychostimulant, is the main compound of EDs which also contain other substances with pharmacological effects. This review aims to compile current evidence concerning the potential interactions between EDs, medicines, and drugs of abuse as they are frequently consumed in combination. The substances involved are mainly substrates, inductors or inhibitors of CYP1A2, psychostimulants, alcohol and other depressant drugs. Furthermore, intoxications reported with EDs and other substances have also been screened to describe acute toxicity. The results of our review show that the consumption of both EDs alone and in combination is not as safe as previously thought. Health professionals and consumers need to be aware of the potential interactions of these drinks as well as the absence of long-term safety data.

Effects of Mixing Energy Drinks With Alcohol on Driving-Related Skills

BACKGROUND

Energy drinks (EDs) reduce sleepiness and fatigue and improve driving performance whereas alcohol does just the opposite. Although it is a trendy combination among young people, the effects of alcohol mixed with EDs on driving performance have been poorly studied. The aim was to assess if there is an interaction between the effects of both drinks on driving-related skills as well as perceptions about driving ability.

METHODS

We conducted a randomized, double-blind, and placebo-controlled 4-way crossover clinical trial. Participants were 16 healthy volunteers. Interventions of 60 g of ethanol and 750 mL of Red Bull (RB) were administered in 2 separated doses. Conditions were alcohol + RB placebo, alcohol + RB, alcohol placebo + RB, and both placebos. Objective performance was assessed using a tracking test and simple reaction time, N-Back, and movement estimation tasks. Additionally, willingness to drive, other subjective effects, and ethanol and caffeine blood concentrations were also measured.

RESULTS

Alcohol increased the time outside the road in the tracking test and increased simple reaction time, but the addition of RB had no main or interaction effects on performance. Nonetheless, driving-related skills after alcohol + RB were better than after alcohol alone. Willingness to drive increased with the combination of drinks. RB also reduced alcohol-induced sedation whereas drunkenness did not change. These effects were seen even though alcohol + RB increased alcohol (14.8%) and caffeine plasma concentrations (17.6%).

CONCLUSIONS

Mixing EDs with alcohol predisposes consumers to drive under alcohol influence, perhaps in part because EDs counteract its detrimental effects on driving-related skills. Clinicaltrials.gov: NCT02771587.

The effects of caffeinated products on sleep and functioning in the military population: A focused review

Military personnel rely on caffeinated products such as coffee or energy drinks (ED) to maintain a maximal level of vigilance and performance under sleep-deprived and combat situations. While chronic caffeine intake is associated with decreased sleep duration and non-restful sleep in the general population, these relationships are relatively unclear in the military personnel. We conducted a focused review of the effects of caffeinated products on sleep and the functioning of military personnel. We used a pre-specified search algorithm and identified 28 peer-reviewed articles published between January 1967 and July 2019 involving military personnel. We classified the findings from these studies into three categories. These categories included descriptive studies of caffeine use, studies evaluating the association between caffeinated products and sleep or functioning measures, and clinical trials assessing the effects of caffeinated products on functioning in sleep-deprived conditions. Most of the studies showed that military personnel used at least one caffeine-containing product per day during active duty and coffee was their primary source of caffeine. Their mean caffeine consumption varied from 212 to 285 mg/day, depending on the type of personnel and their deployment status. Those who were younger than 30 years of age preferred ED use. Caffeine use in increasing amounts was associated with decreased sleep duration and increased psychiatric symptoms. The consumption of caffeinated products during sleep deprivation improved their cognitive and behavioral outcomes and physical performance. Caffeine and energy drink consumption may maintain some aspects of performance stemming from insufficient sleep in deployed personnel, but excessive use may have adverse consequences.

Impact of Caffeine on Ethanol-Induced Stimulation and Sensitization: Changes in ERK and DARPP-32 Phosphorylation in Nucleus Accumbens

BACKGROUND

Caffeine is frequently consumed with ethanol to reduce the impairing effects induced by ethanol, including psychomotor slowing or incoordination. Both drugs modulate dopamine (DA)-related markers in accumbens (Acb), and Acb DA is involved in voluntary locomotion and locomotor sensitization. The present study determined whether caffeine can affect locomotion induced by acute and repeated ethanol administration in adult male CD-1 mice.

METHODS

Acute administration of caffeine (7.5 to 30.0 mg/kg) was evaluated for its effects on acute ethanol-induced (1.5 to 3.5 g/kg) changes in open-field horizontal locomotion, supported rearing, and rearing not supported by the wall. DA receptor-dependent phosphorylation markers were assessed: extracellular signal-regulated kinase (pERK), and dopamine-and cAMP-regulated phosphoprotein Mr32kDa phosphorylated at threonine 75 site (pDARPP-32-Thr75) in Acb core and shell. Acutely administered caffeine was also evaluated in ethanol-sensitized (1.5 g/kg) mice.

RESULTS

Acute ethanol decreased both types of rearing. Caffeine increased supported rearing but did not block ethanol -induced decreases in rearing. Both substances increased horizontal locomotion in a biphasic manner, and caffeine potentiated ethanol-induced locomotion. Although ethanol administered repeatedly induced sensitization of locomotion and unsupported rearing, acute administration of caffeine to ethanol-sensitized mice in an ethanol-free state resulted in blunted stimulant effects compared with those seen in ethanol-naïve mice. Ethanol increased pERK immunoreactivity in both subregions of the Acb, but coadministration with caffeine blunted this increase. There were no effects on pDARPP-32(Thr75) immunoreactivity.

CONCLUSIONS

The present results demonstrated that, after the first administration, caffeine potentiated the stimulating actions of ethanol, but did not counteract its suppressant or ataxic effects. Moreover, our results show that caffeine has less activating effects in ethanol-sensitized animals.

Drinking contexts and their association with acute alcohol-related harm: A systematic review of event-level studies on adults' drinking occasions

ISSUES

Event-level alcohol research can inform prevention efforts by determining whether drinking contexts-such as people or places-are associated with harmful outcomes. This review synthesises evidence on associations between characteristics of adults' drinking occasions and acute alcohol-related harm.

APPROACH

We systematically searched Ovid MEDLINE, Ovid PsycInfo and the Web of Science Social Sciences Citation Index. Eligible papers used quantitative designs and event-level data collection methods. They linked one or more drinking contexts to acute alcohol-related harm. Following extraction of study characteristics, methods and findings, we assessed study quality and narratively synthesised the findings.

PROSPERO ID

CRD42018119701.

KEY FINDINGS

Searches identified 95 eligible papers, 65 (68%) of which study young adults and 62 (65%) of which are set in the United States, which limits generalisability to other populations. These papers studied a range of harms from assault to drink driving. Study quality is good overall although measures often lack validation. We found substantial evidence for direct effects of drinking context on harms. All of the contextual characteristics types studied (e.g. people, place, timing, psychological states, drink type) were consistently associated with harms. Certain contexts were frequently studied and associated with harms, in particular, weekend drinking, drinking in licensed premises and concurrent illicit drug use.

IMPLICATIONS

The findings of our review indicate target drinking contexts for prevention efforts that are consistently associated with increased acute alcohol-related harm.

CONCLUSION

A large range of contextual characteristics of drinking occasions are directly associated with acute alcohol-related harm, over and above levels of consumption.

Contextual characteristics of adults' drinking occasions and their association with levels of alcohol consumption and acute alcohol-related harm: a mapping review

BACKGROUND AND AIMS

There is a growing literature using event-level methods to estimate associations between contextual characteristics of drinking occasions, consumption levels and acute harms. This literature spans many research traditions and has not been brought together as a whole. This mapping review aimed to identify and describe the theoretical approaches to conceptualizing drinking occasions, study designs, predictors and outcome measures used in existing research with a view to identifying dominant approaches, research gaps and areas for further synthesis.

METHODS

Eligible papers studied adults' drinking occasions using quantitative event-level methods and considered one or more contextual characteristics (e.g. venue, timing or company) and at least one event-level consumption or acute alcohol-related harm outcome. We systematically searched Ovid MEDLINE, PsycInfo and the Web of Science Social Sciences Citation Index, extracting data on studies' theoretical approach, data collection methods, settings, populations, drinking occasion characteristics and outcome measures.

RESULTS

Searches identified 278 eligible papers (from 1975 to 2019), predominantly published after 2010 (n = 181; 65.1%). Most papers reported research conducted in the United States (n = 170; 61.2%) and half used student participants (n = 133; 47.8%). Papers typically lacked a stated theoretical approach (n = 203; 73.0%). Consistent with this, only 53 (19.1%) papers studied three or more occasion characteristics and most used methods that assume occasion characteristics do not change during an occasion (n = 189; 68.0%). The most common outcome type considered was consumption (n = 224; 80.6%) and only a few papers studied specific acute harm outcomes such as unprotected sex (n = 24; 8.6%), drink driving (n = 14; 5.0%) or sexual violence (n = 9; 3.2%).

CONCLUSIONS

Studies from 1975 to 2019 using event-level methods to estimate associations between contextual characteristics of drinking occasions, consumption levels and acute harms were largely focused on students and consumption outcomes, and most have considered a limited range of contextual characteristics.

Use of Alcohol Mixed with Energy Drinks Increases the Prevalence of Driving Violations among Brazilian Truck Drivers

Background: The use of alcohol mixed with energy drinks (AmED) has been reported to be associated with a variety of unsafe driving practices. Truck drivers are vulnerable to driving violations, particularly because of their engagement in drug use. The use of AmED among these professionals remains unknown. Aim: To estimate the prevalence of AmED use and its association with driving violations among truck drivers. Methods: 684 drivers were recruited in Sao Paulo, Brazil. The use of drugs was reported. Drivers were split into three groups: (a) alcohol abstainers (AA); (b) alcohol-only users (AO); and (c) users of AmED. Intergroup comparisons were performed by polynomial logistic regression (the reference category was AO). We also performed Poisson regression analysis to obtain the prevalence ratio; the significance level was stipulated at 5%. Results: The prevalence of drivers reporting the use of AmED was 16.8%. Users of AmED (a) were younger, (b) were less experienced drivers, (c) had a heavier pattern of alcohol use, (d) used illicit drugs more frequently, and (e) had poorer sleep quality than AO subjects. A higher prevalence of drivers who had arguments or fights while driving (PR = 1.71) and of drivers who drove unbelted (PR = 1.66) ingested AmED than of AO subjects. Conclusions/importance: The use of AmED increased the prevalence of driving violations beyond the risks commonly attributed to alcohol use. We suggest additional investments in preventative measures based on the beverage category and a revision of the work organization of truck drivers to reduce their health and social risks.

Alcohol mixed with energy drink use during young adulthood

AIMS

Alcohol mixed with energy drink (AmED) use is associated with negative consequences including hazardous alcohol use and driving under the influence. While many studies have focused on correlates of AmED use among college samples, very few have examined patterns of AmED use during adolescence and young adulthood within the general population. Accordingly, the purpose of this study is to assess age differences in AmED use among a national sample of respondents aged 18 to 30.

METHODS

The data for this study come from the Monitoring the Future panel study from 2012 to 2015. The sample consists of 2222 respondents between the ages of 18 and 30. Multiple logistic regression using generalized estimating equations (GEE) was used to model past-year AmED prevalence across age and other covariates.

RESULTS

Nearly half (45.0%) of respondents indicated past-year AmED use at some point during the study period. The lowest prevalence rates were found at age 18 (25.9%) and the highest prevalence rates at age 21/22 (43.5%). GEE analyses indicated a statistically significant positive linear and negative quadratic trend with respect to the association between age of respondent and past-year AmED use. Namely, peak use occurred in early young adulthood (age 21/22 and 23/24) and then declined, reaching 32.0% by age 29/30. College attendance and several substance use behaviors at age 18 moderated these linear and quadratic age trends.

CONCLUSIONS

AmED use peaked rapidly in early young adulthood and declined into later young adulthood. Substance use during adolescence was associated with a higher incidence of AmED use across all young adult ages and a slower decline of AmED use after age 21/22. Several sociodemographic factors were associated with AmED use, particularly college attendance at the age of 21/22.

Red Bull® energy drink increases consumption of higher concentrations of alcohol

Mixing alcohol with caffeinated energy drinks is a common practice, especially among young people. In humans, the research on this issue has mainly focused on the use of the mass-marketed energy drinks themselves, whereas in animal models, it has focused on the individual effects of their active ingredients (i.e. caffeine). Here, we have characterized how Red Bull®, one of the most consumed caffeinated energy drink worldwide, modulates operant alcohol self-administration in Wistar rats. We found that animals readily and steadily responded for Red Bull (mean: 90 responses, 30 minutes and fixed-ratio 1), which was accompanied by locomotor stimulating effects (26 percent increase). The higher the concentration of alcohol (3-20 percent), the higher the consumption of alcohol (g/kg) and associated blood alcohol levels (91.76 percent) in the mixed Red Bull-alcohol group (60 percent increase). Blood caffeine levels in the Red Bull group were 4.69 μg/ml and 1.31 μg/ml in the Red Bull-alcohol group after the 30-minute session. Because Red Bull also contains 11 percent sucrose, we examined the time course of blood glucose as well as insulin and corticosterone. The correlation between intake of Red Bull and blood glucose levels was higher at 90 minutes than 5 minutes after its consumption, and there was no relationship with blood insulin or blood corticosterone levels. Red Bull did not alter extinction and reacquisition of responding for alcohol nor did it affect relapse-like drinking. Overall, our results suggest that Red Bull might be a vulnerability factor to develop alcoholism given that it intensifies the consumption of higher concentrations of alcohol.

The multiplicative effect of combining alcohol with energy drinks on adolescent gambling

PURPOSE

There has been increased concern about the negative effects of adolescents consuming a combination of alcohol mixed with energy drinks (AmED). To date, few studies have focused on AmED use and gambling. The present study analyzed the multiplicative effect of AmED consumption, compared to alcohol alone, on the likelihood of at-risk or problem gambling during adolescence.

METHODS

Data from the ESPAD®Italia 2015 study, a cross-sectional survey conducted in a nationally representative sample of students (ages 15 to 19years) were used to examine the association between self-reported AmED use (≥6 times,≥10 times, and ≥20 times during the last month) and self-reported gambling severity. Multivariate models were used to calculate adjusted prevalence ratios to evaluate the association between alcohol use, AmED use, and gambling among a representative sample of adolescents who reported gambling in the last year and completed a gambling severity scale (n=4495).

RESULTS

Among the 19% students classed as at-risk and problem gamblers, 43.9% were classed as AmED consumers, while 23.6% were classed as alcohol consumers (i.e. did not mix alcohol with energy drinks). In multivariate analyses that controlled for covariates, AmED consumers were three times more likely to be at-risk and problem gamblers (OR=3.05) compared to non-consuming adolescents, while the effect became less pronounced with considering those who consumed alcohol without the addition of energy drinks (OR=1.37).

CONCLUSIONS

The present study clearly established that consuming AmED might pose a significantly greater risk of experiencing gambling-related problems among adolescents.

Perception of intoxication in a field study of the night-time economy: Blood alcohol concentration, patron characteristics, and event-level predictors

OBJECTIVE

Determine the relationship of subjective intoxication to blood alcohol concentration (BAC) and examine whether patron and event-level characteristics modify the relationship of BAC to subjective intoxication.

METHODS

An in-situ systematic random sample of alcohol consumers attending night-time entertainment districts between 10pm and 3am on Friday and Saturday nights in five Australian cities completed a brief interview (n=4628). Participants reported age, sex, and pre-drinking, energy drink, tobacco, illicit stimulant and other illicit drug use that night, and their subjective intoxication and BAC were assessed.

RESULTS

Male and female drinkers displayed equally low sensitivity to the impact of alcohol consumption when self-assessing their intoxication (BAC only explained 19% of variance). The marginal effect of BAC was not constant. At low BAC, participants were somewhat sensitive to increases in alcohol consumption, but at higher BAC levels that modest sensitivity dissipated (actual BAC had less impact on self-assessed intoxication). The slope ultimately leveled out to be non-responsive to additional alcohol intake. Staying out late, pre-drinking, and being young introduced biases resulting in higher self-assessed intoxication regardless of actual BAC. Further, both energy drinks and stimulant use modified the association between BAC and perceived intoxication, resulting in more compressed changes in self-assessment as BAC varies up or down, indicating less ability to perceive differences in BAC level.

CONCLUSIONS

The ability of intoxicated patrons to detect further intoxication is impaired. Co-consumption of energy drinks and/or stimulant drugs is associated with impaired intoxication judgment, creating an additional challenge for the responsible service and consumption of alcohol.

Alcohol-Induced Impairment of Balance is Antagonized by Energy Drinks

BACKGROUND

The acute administration of alcohol reliably impairs balance and motor coordination. While it is common for consumers to ingest alcohol with other stimulant drugs (e.g., caffeine, nicotine), little is known whether prototypical alcohol-induced balance impairments are altered by stimulant drugs. The purpose of this study was to examine whether the coadministration of a high-caffeine energy drink with alcohol can antagonize expected alcohol-induced increases in body sway.

METHODS

Sixteen social drinkers (of equal gender) participated in 4 separate double-blind dose administration sessions that involved consumption of alcohol and energy drinks, alone and in combination. Following dose administration, participants completed automated assessments of balance stability (both eyes open and eyes closed) measured using the Biosway Portable Balance System. Participants completed several subjective measures including self-reported ratings of sedation, stimulation, fatigue, and impairment. Blood pressure and pulse rate were recorded repeatedly.

RESULTS

The acute administration of alcohol increased body sway, and the coadministration of energy drinks antagonized this impairment. When participants closed their eyes, alcohol-induced body sway was similar whether or not energy drinks were ingested. While alcohol administration increased ratings of sedation and fatigue, energy drink administration increased ratings of stimulation and reduced ratings of fatigue. Modest increases in systolic and diastolic blood pressure following energy drink administration were also observed.

CONCLUSIONS

Visual assessment of balance impairment is frequently used to indicate that an individual has consumed too much alcohol (e.g., as part of police-standardized field sobriety testing or by a bartender assessing when someone should no longer be served more alcohol). The current findings suggest that energy drinks can antagonize alcohol-induced increases in body sway, indicating that future work is needed to determine whether this observation regarding neuromotor functioning applies to alcohol in combination with all types of stimulant drugs.

Effects of caffeinated alcoholic beverages with low alcohol and high caffeine content on cognitive and motor functions

OBJECTIVE

In Taiwan, caffeinated alcoholic beverages (CABs), with high caffeine but low alcohol concentrations compared to those sold in Western countries, are commonly consumed at work and have been associated with work-related injuries. However, the effects on cognitive and motor functions and self-perception have not been examined.

METHODS

Twenty-eight healthy male volunteers (mean age: 32.6 ± 2.7) participated in the study. Each participant visited our laboratory 4 times at intervals of at least 1 week and was assigned to one of 4 trials in a counterbalanced order at each visit: placebo, alcohol, caffeinated energy drink, and CAB. They completed the subjective perception ratings, go/no-go tasks, Stroop color-word tests, Purdue pegboard tests, and the standardized field sobriety test. We used analysis of variance to examine the intraindividual differences in the performance.

RESULTS

Consuming alcohol of 0.23 g/kg typically consumed by Taiwanese CAB drinkers caused significant impairments in fine and crude motor functions; caffeine (1.5 mg/kg) did not antagonize these effects but led to an improvement in response speed in the go/no-go task. The subjective perceptions produced by alcohol were not masked by caffeine.

CONCLUSIONS

CABs that contains a higher ratio of caffeine to alcohol did not counteract the motor function impairments induced by alcohol.

Nature versus intensity of intoxication: Co-ingestion of alcohol and energy drinks and the effect on objective and subjective intoxication

BACKGROUND

We report a series of studies examining the effect of alcohol mixed with energy drinks (AmEDs) versus alcohol on objective intoxication (breath alcohol concentration; BrAC), intensity, and nature of intoxication. We also aimed to disentangle the role of energy drink (ED) ingredients in any effects.

METHOD

Three within-subject double-blind placebo-controlled studies measured BrAC, subjective intoxication and impairment ('intensity of intoxication'), stimulation and sedation ('nature of intoxication') following administration of ED, Cola, Caffeine+Sugar, and Placebo with alcohol (Study 1, n=18); ED, Caffeine-only, Sugar-only and Placebo with alcohol (Study 2, n=20); and ED and Placebo with alcohol (Study 3, n=27).

RESULTS

Significant moderate-to-large magnitude BrAC decrements and delayed time to peak BrAC were observed after ED administration versus Placebo. However, no meaningful BrAC differences between ED and other active conditions were observed in Study 1 and 2. After BrAC adjustment, moderate-to-large magnitude reductions in intoxication and impairment ratings were observed after ED versus Placebo on the ascending limb in all studies and at peak in Study 2 and 3. No meaningful differences were observed in intoxication and impairment ratings between ED and Caffeine+Sugar and Cola conditions (Study 1); ratings were lower after ED versus Sugar-only (Study 2). Stimulation and sedation ratings did not differ between ED and Placebo.

CONCLUSION

Reductions in objective intoxication and perceived intensity of intoxication, but not nature of intoxication, were observed after AmED consumption. However, effects may be common to alcohol mixers containing sugars (objective intoxication) and caffeine (intensity of intoxication) and specific to a laboratory setting.

The need for accuracy and validity in research on nightlife and drinking: A commentary on Devilly et al. and recommendations for future research

Research on nightlife and drinking faces many unique challenges, and validity in research is an important concern. A recent publication by Devilly et al. entitled "SmartStart: Results of a large point of entry study into preloading alcohol and associated behaviours" contains definitions and assumptions about prior work that require more careful consideration. Important issues include: using a definition of pre-drinking which is the same as previous work so that valid comparison can be made, reporting of blood alcohol concentration (BAC) levels that comply with other work, accurate reporting of response rates, and careful consideration of sampling approaches to maximise ethical integrity. Ensuring consistency of definition and accurate representation of previous literature regarding BAC, pre-drinking and energy drink use, is important for supplying the broader community with reliable information on which policy decisions can be made.

Energy and sports drinks in children and adolescents

Sports drinks and caffeinated energy drinks (CEDs) are commonly consumed by youth. Both sports drinks and CEDs pose potential risks for the health of children and adolescents and may contribute to obesity. Sports drinks are generally unnecessary for children engaged in routine or play-based physical activity. CEDs may affect children and adolescents more than adults because they weigh less and thus experience greater exposure to stimulant ingredients per kilogram of body weight. Paediatricians need to recognize and educate patients and families on the differences between sport drinks and CEDs. Screening for the consumption of CEDs, especially when mixed with alcohol, should be done routinely. The combination of CEDs and alcohol may be a marker for higher risk of substance use or abuse and for other health-compromising behaviours.

Energy Drink and Alcohol mixed Energy Drink use among high school adolescents: Association with risk taking behavior, social characteristics

PURPOSE

The aims of the study were to: a) examine the prevalence of energy drink (ED) and alcohol mixed with energy drink (AmED) consumption; b) investigate the relationships between ED and AmED with alcohol, binge drinking and drugs accounting for at risk behaviors among a representative sample of Italian adolescents.

METHODS

A representative sample of 30,588 Italian high school students, aged 15-19years, was studied. Binary and multivariate logistic regression analyses were performed to determine the independent association of the potential predictors' characteristics with the ED and AmED drinking during the last year.

RESULTS

Respectively 41.4% and 23.2% of respondents reported drinking EDs and AmEDs in the last year. Multivariate analysis revealed that consumption of EDs and AmEDs during the last year were significantly associated with daily smoking, binge drinking, use of cannabis and other psychotropic drugs. Among life habits and risky behaviors the following were positively associated: going out with friends for fun, participating in sports, experiencing physical fights/accidents or injury, engaging in sexual intercourse without protection and being involved in accidents while driving.

CONCLUSIONS

This study demonstrates the popularity of ED and AmED consumption among the Italian school population aged 15-19years old: 4 out of 10 students consumed EDs in the last year and 2 out of 10 AmED. Multivariate analysis highlighted the association with illicit drug consumption and harming behaviors, confirming that consumption of EDs and AmEDs is a compelling issue especially during adolescence, as it can effect health as well as risk taking behaviors.

Combined use of alcohol and energy drinks: Dose relationship with self-reported physiological stimulation and sedation side effects

BACKGROUND

Negative physiological stimulation and sedation side effects are experienced by a significant proportion of consumers who consume alcohol mixed with energy drinks (AmED). Few studies have compared the frequency of side effects between sessions of AmED and sessions of alcohol only within-subject, and none have explored a dose relationship.

OBJECTIVES

Explore the occurrence of self-reported physiological stimulant and sedative side effects between sessions of AmED and alcohol only, and at varying ED dosage levels within AmED sessions.

METHODS

A convenience sample of 2953 residents of New South Wales, Australia completed an online survey. N=731 AmED users reported daily caffeine intake, typical alcohol and AmED consumption, and past 12-month experience of physiological stimulation and sedation side effects during AmED and alcohol only sessions. Within-subject analyses compared occurrence of side effects between session types. Hierarchical binary logistic regression analyses explored the association of ED dose during AmED sessions with the experience of physiological side effects.

RESULTS

There were greater odds of most stimulant side effects, and lower odds of sedation side effects, during AmED sessions compared to alcohol only sessions. Compared to one ED, consumption of three or more EDs was significantly associated with the majority of both stimulant and alcohol intoxication side effects after controlling for demographics and consumption covariates.

CONCLUSIONS

AmED is associated with perceived changes in physiological stimulant and sedation side effects of alcohol. Experience of side effects is positively associated with ED dosage. Future research should account for varying ED dosage, and reflect real world consumption levels.

Energy drinks and alcohol-related risk among young adults

BACKGROUND

Energy drink consumption, with or without concurrent alcohol use, is common among young adults. This study sought to clarify risk for negative alcohol outcomes related to the timing of energy drink use.

METHODS

The authors interviewed a community sample of 481 young adults, aged 18-25, who drank alcohol in the last month. Past-30-day energy drink use was operationalized as no-use, use without concurrent alcohol, and concurrent use of energy drinks with alcohol ("within a couple of hours"). Negative alcohol outcomes included past-30-day binge drinking, past-30-day alcohol use disorder, and drinking-related consequences.

RESULTS

Just over half (50.5%) reported no use of energy drinks,18.3% reported using energy drinks without concurrent alcohol use, and 31.2% reported concurrent use of energy drinks and alcohol. Relative to those who reported concurrent use of energy drinks with alcohol, and controlling for background characteristics and frequency of alcohol consumption, those who didn't use energy drinks and those who used without concurrent alcohol use had significantly lower binge drinking, negative consequences, and rates of alcohol use disorder (P < .05 for all outcomes). There were no significant differences between the no-use and energy drink without concurrent alcohol groups on any alcohol-related measure (P > .10 for all outcomes).

CONCLUSIONS

Concurrent energy drink and alcohol use is associated with increased risk for negative alcohol consequences in young adults. Clinicians providing care to young adults could consider asking patients about concurrent energy drink and alcohol use as a way to begin a conversation about risky alcohol consumption while addressing 2 substances commonly used by this population.

The Safety of Ingested Caffeine: A Comprehensive Review

Caffeine is the most widely consumed psychoactive drug in the world. Natural sources of caffeine include coffee, tea, and chocolate. Synthetic caffeine is also added to products to promote arousal, alertness, energy, and elevated mood. Over the past decade, the introduction of new caffeine-containing food products, as well as changes in consumption patterns of the more traditional sources of caffeine, has increased scrutiny by health authorities and regulatory bodies about the overall consumption of caffeine and its potential cumulative effects on behavior and physiology. Of particular concern is the rate of caffeine intake among populations potentially vulnerable to the negative effects of caffeine consumption: pregnant and lactating women, children and adolescents, young adults, and people with underlying heart or other health conditions, such as mental illness. Here, we review the research into the safety and safe doses of ingested caffeine in healthy and in vulnerable populations. We report that, for healthy adults, caffeine consumption is relatively safe, but that for some vulnerable populations, caffeine consumption could be harmful, including impairments in cardiovascular function, sleep, and substance use. We also identified several gaps in the literature on which we based recommendations for the future of caffeine research.

Energy drink use frequency among an international sample of people who use drugs: Associations with other substance use and well-being

OBJECTIVE

The study aims were to identify: i.) energy drink (ED), caffeine tablet, and caffeine intranasal spray use amongst a sample who report drug use, and ii.) the association between ED use frequency and demographic profile, drug use, hazardous drinking, and wellbeing.

METHOD

Participants (n=74,864) who reported drug use completed the online 2014 Global Drug Survey. They provided data on demographics, ED use, and alcohol and drug use, completed the Alcohol Use Disorders Identification Test (AUDIT) and Personal Wellbeing Index (PWI), and reported whether they wished to reduce alcohol use.

RESULTS

Lifetime ED, caffeine tablet and intranasal caffeine spray use were reported by 69.2%, 24.5% and 4.9%. Median age of ED initiation was 16 years. For those aged 16-37, median years using EDs increased from 4 to 17 years of consumption, where it declined thereafter. Greater ED use frequency was associated with: being male; under 21 years of age; studying; and past year caffeine tablet/intranasal spray, tobacco, cannabis, amphetamine, MDMA, and cocaine use. Past year, infrequent (1-4days) and frequent (≥5days) past month ED consumers reported higher AUDIT scores and lower PWI scores than lifetime abstainers; past month consumers were less likely to report a desire to reduce alcohol use.

CONCLUSIONS

ED use is part of a complex interplay of drug use, alcohol problems, and poorer personal wellbeing, and ED use frequency may be a flag for current/future problems. Prospective research is required exploring where ED use fits within the trajectory of other alcohol and drug use.

Correlates of verbal and physical aggression among patrons of licensed venues in Australia

INTRODUCTION AND AIMS

The current study aimed to examine the association between patron demographics and substance use, and experiences of verbal and physical aggressive incidents within the last 3 months among patrons of night-time entertainment precincts (NEP) in Australia.

DESIGN AND METHODS

Patron interviews (n = 4216) were conducted around licensed venues in the NEPs of five Australian cities. Seven correlates of verbal and physical aggressive incidents were examined: gender, age, occupation, blood alcohol concentration, pre-drinking, energy drink use and illicit drug use in the current session.

RESULTS

A total of 7.5% and 8.2% of respondents reported involvement in a verbally and physically aggressive incident in the past 3 months, respectively. Multivariate logistic regression models indicated men and people <25 years old were significantly more likely to report both verbal and physical aggressive incidents. A significant occupation effect showed lower levels of both verbal and physical aggression in managers/professionals compared with non-office workers. The likelihood of being involved in a verbally aggressive incident significantly increased with energy drink consumption, while the likelihood of being involved in a physically aggressive incident significantly increased with blood alcohol concentration, energy drink consumption and illicit drug use.

DISCUSSION AND CONCLUSIONS

This study highlights the different correlates of verbal and physical aggression within NEPs, suggesting they should be viewed as distinct types of violence, rather than points on a continuum. Major modifiable correlates with verbal and physical aggression included intoxication, energy drink consumption, and illicit drug use, suggesting the need for further interventions and policy development to address these key issues. [Hyder S, Coomber K, Pennay A, Droste N, Curtis A, Mayshak R, Lam T, Gilmore W, Chikritzhs T, Miller PG. Correlates of verbal and physical aggression among patrons of licensed venues in Australia. Drug Alcohol Rev 2018;37:6-13].

Energy Drink Use Patterns Among Young Adults: Associations with Drunk Driving

BACKGROUND

Highly caffeinated "energy drinks" (ED) are commonly consumed and sometimes mixed with alcohol. Associations between ED consumption, risk-taking, and alcohol-related problems have been observed. This study examines the relationship between ED consumption-both with and without alcohol-and drunk driving.

METHODS

Data were derived from a longitudinal study of college students assessed annually via personal interviews. In Year 6 (modal age 23; n = 1,000), participants self-reported their past-year frequency of drunk driving, ED consumption patterns (frequency of drinking alcohol mixed with energy drinks [AmED] and drinking energy drinks without alcohol [ED]), alcohol use (frequency, quantity), and other caffeine consumption. Earlier assessments captured suspected risk factors for drunk driving. Structural equation modeling was used to develop an explanatory model for the association between ED consumption patterns and drunk driving frequency while accounting for other suspected risk factors.

RESULTS

More than half (57%) consumed ED at least once during the past year. Among ED consumers, 71% drank AmED and 85% drank ED alone; many (56%) engaged in both styles of ED consumption while others specialized in one or the other (29% drank ED alone exclusively, while, 15% drank AmED exclusively). After accounting for other risk factors, ED consumption was associated with drunk driving frequency in 2 ways. First, a direct path existed from ED frequency (without alcohol) to drunk driving frequency. Second, an indirect path existed from AmED frequency through alcohol quantity to drunk driving frequency.

CONCLUSIONS

Among this sample, ED consumption with and without alcohol was common, and both styles of ED consumption contributed independently to drunk driving frequency. Results call for increased attention to the impact of different patterns of ED consumption on alcohol-related consequences, such as drunk driving.

Environmental contexts of combined alcohol and energy drink use: Associations with intoxication in licensed venues

BACKGROUND

Environmental factors inside licensed venues have been found to influence the intoxication levels and consumption practices of patrons. The consumption of alcohol mixed with energy drinks (AmED) occurs primarily at or prior to attending licensed venues, however there is a lack of in situ research investigating AmED use in these contexts. Given that AmED use has been linked with increased alcohol consumption, intoxication, illicit substance use, and risk taking behaviours, this paper explores the environmental correlates and levels of intoxication associated with AmED use in licensed venues.

METHODS

Structured observations were undertaken in five Australian cities on Friday and Saturday nights. Covert teams spent 4-5h in venues and recorded hourly observations on patron, venue, and staff characteristics, alcohol, illicit drug and AmED consumption patterns and intoxication levels.

RESULTS

898 hourly observations were recorded across 68 venues. All but one venue served energy drinks, and patron AmED use was observed during 34.9% of hourly records. AmED use was more prevalent after 12am and in nightclub venues compared to bars and pubs, and was positively associated with high intoxication levels, illicit drug use, and younger crowds. After controlling for environmental factors (i.e. venue crowding, service practices, venue characteristics, patron demographics and behaviour) AmED use did not predict high intoxication at a venue level in multivariable models.

CONCLUSION

AmED consumption is ubiquitous in the licensed venues of Australian night-time entertainment districts, particularly busy nightclub venues where intoxication and risky consumption are heightened. However, AmED use was not associated with high patron intoxication when environmental factors were considered.

Unique Behavioral and Neurochemical Effects Induced by Repeated Adolescent Consumption of Caffeine-Mixed Alcohol in C57BL/6 Mice

The number of highly caffeinated products has increased dramatically in the past few years. Among these products, highly caffeinated energy drinks are the most heavily advertised and purchased, which has resulted in increased incidences of co-consumption of energy drinks with alcohol. Despite the growing number of adolescents and young adults reporting caffeine-mixed alcohol use, knowledge of the potential consequences associated with co-consumption has been limited to survey-based results and in-laboratory human behavioral testing. Here, we investigate the effect of repeated adolescent (post-natal days P35-61) exposure to caffeine-mixed alcohol in C57BL/6 mice on common drug-related behaviors such as locomotor sensitivity, drug reward and cross-sensitivity, and natural reward. To determine changes in neurological activity resulting from adolescent exposure, we monitored changes in expression of the transcription factor ΔFosB in the dopaminergic reward pathway as a sign of long-term increases in neuronal activity. Repeated adolescent exposure to caffeine-mixed alcohol exposure induced significant locomotor sensitization, desensitized cocaine conditioned place preference, decreased cocaine locomotor cross-sensitivity, and increased natural reward consumption. We also observed increased accumulation of ΔFosB in the nucleus accumbens following repeated adolescent caffeine-mixed alcohol exposure compared to alcohol or caffeine alone. Using our exposure model, we found that repeated exposure to caffeine-mixed alcohol during adolescence causes unique behavioral and neurochemical effects not observed in mice exposed to caffeine or alcohol alone. Based on similar findings for different substances of abuse, it is possible that repeated exposure to caffeine-mixed alcohol during adolescence could potentially alter or escalate future substance abuse as means to compensate for these behavioral and neurochemical alterations.

Problematic Drinking Among Postgraduate Students: Binge Drinking, Prepartying, and Mixing Alcohol With Energy Drinks

BACKGROUND

Although problematic alcohol use has been studied extensively in undergraduate students, little is known about problematic drinking among postgraduate students.

OBJECTIVES

This study examined binge drinking, prepartying, and mixing alcohol with energy drinks to determine: (1) the extent to which postgraduate students engage in these drinking behaviors, (2) how postgraduate students differ from undergraduate students in these behaviors, and (3) the demographic risk factors for these behaviors in postgraduate (and undergraduate) students.

METHODS

This study utilized data from n = 695 students (n = 298 postgraduate; n = 397 undergraduate) who participated in the Healthy Minds Study at a large, public university in the Midwestern US.

RESULTS

Past-two-week binge drinking, past-year and past-30-day prepartying, and past-30-day mixing alcohol with energy drinks were reported by 26.2%, 28.6%, 14.9%, and 8.1% of postgraduate students, respectively. Multivariate analyses indicated that postgraduate status was a significant negative predictor of binge drinking and prepartying, and that status interacted with age in predicting prepartying such that the effect of age on prepartying was negative for postgraduate students and nonsignificant for undergraduates. Age was a significant negative predictor of mixing alcohol with energy drinks for all students.

CONCLUSIONS/IMPORTANCE

This study makes a unique contribution to the literature by providing information on problematic drinking in postgraduate students. Although there was evidence of "maturing out," a substantial number of postgraduate students were found to engage in binge drinking and prepartying, and a not insubstantial number of them were found to mix alcohol with energy drinks.

Alcohol mixed with energy drink: Use may be a consequence of heavy drinking

AIMS

In recent years, studies have indicated that consumers of alcohol mixed with energy drink (AmED) are more likely to drink heavily and experience more negative consequences than consumers who avoid these beverages. Although researchers have identified a number of plausible hypotheses that explain how alcohol-energy drink co-ingestion could cause greater alcohol consumption, there has been no postulation about reverse causal relations. This paper identifies several plausible hypotheses for the observed associations between AmED consumption and greater alcohol consumption, and provides initial evidence for one such hypothesis suggesting that heavy drinking may be a determinant of AmED use.

METHOD

Data collected from 511bar patrons were used to examine the plausibility of one of the proposed hypotheses, i.e., AmED is an artifact of heavy drinking. Associations between the consumption of an assortment of alcoholic beverage types and total alcohol consumption were examined at the event-level, to assess whether AmED is uniquely related with greater alcohol consumption.

RESULTS

Increased alcohol consumption was associated with greater odds of consuming most alcoholic beverage types; this association was not unique to AmED.

CONCLUSIONS

Results support the overlooked hypothesis that AmED use is an artifact of heavy drinking. Thus, AmED consumption may be a consequence or marker of heavier drinking. Much of the existing research on alcoholic beverage types is limited in its ability to implicate any specific type of drink, including AmED, as a cause of increased alcohol consumption and related harm. More rigorous study designs are needed to examine causal relationships.

Mechanisms of the psychostimulant effects of caffeine: implications for substance use disorders

BACKGROUND

The psychostimulant properties of caffeine are reviewed and compared with those of prototypical psychostimulants able to cause substance use disorders (SUD). Caffeine produces psychomotor-activating, reinforcing, and arousing effects, which depend on its ability to disinhibit the brake that endogenous adenosine imposes on the ascending dopamine and arousal systems.

OBJECTIVES

A model that considers the striatal adenosine A2A-dopamine D2 receptor heteromer as a key modulator of dopamine-dependent striatal functions (reward-oriented behavior and learning of stimulus-reward and reward-response associations) is introduced, which should explain most of the psychomotor and reinforcing effects of caffeine.

HIGHLIGHTS

The model can explain the caffeine-induced rotational behavior in rats with unilateral striatal dopamine denervation and the ability of caffeine to reverse the adipsic-aphagic syndrome in dopamine-deficient rodents. The model can also explain the weaker reinforcing effects and low abuse liability of caffeine, compared with prototypical psychostimulants. Finally, the model can explain the actual major societal dangers of caffeine: the ability of caffeine to potentiate the addictive and toxic effects of drugs of abuse, with the particularly alarming associations of caffeine (as adulterant) with cocaine, amphetamine derivatives, synthetic cathinones, and energy drinks with alcohol, and the higher sensitivity of children and adolescents to the psychostimulant effects of caffeine and its potential to increase vulnerability to SUD.

CONCLUSIONS

The striatal A2A-D2 receptor heteromer constitutes an unequivocal main pharmacological target of caffeine and provides the main mechanisms by which caffeine potentiates the acute and long-term effects of prototypical psychostimulants.

Cognitive impairment following consumption of alcohol with and without energy drinks

BACKGROUND

The aim of this study was to assess the relative effects of alcohol mixed with energy drink (AmED) versus alcohol alone on cognitive performance across the ascending and descending breath alcohol concentration (BrAC) limb using doses similar to real-world intake.

METHODS

Using a single-blind, placebo-controlled, crossover design, 19 participants completed 4 sessions where they received: (i) placebo, (ii) alcohol, (iii) AmED 500 ml energy drink (ED), and (iii) AmED 750 ml ED. Performance on measures of psychomotor function (Compensatory Tracking Task [CTT]), information processing (Digit Symbol Substitution Task [DSST]; Inspection Time Task [ITT]), and response inhibition (Brief Stop-Signal Task [Brief SST]) was assessed at ~0.05% ascending BrAC, ~0.08% peak BrAC, and ~0.05% descending BrAC.

RESULTS

The ITT and Brief SST showed no differential effect of AmED versus alcohol (gs < 0.30 and gs < 0.36, respectively). Moderate magnitude improvements in alcohol-induced impairment of CTT and DSST performance were observed after AmED versus alcohol on the descending BrAC limb (gs > 0.45 and gs > 0.37, respectively). A moderate magnitude decrease in DSST errors was also observed after AmED relative to alcohol at 0.050% ascending target BrAC (gs > 0.43).

CONCLUSIONS

Changes in cognitive function after AmED administration were dependent on the degree of intoxication, BrAC curve limb, and ED volume. Co-administration of ED doses which matched (500 ml) and exceeded (500 ml) maximum daily intake guidelines with alcohol decreased impairment of psychomotor function and global information processing after alcohol consumption. These results cannot be necessarily interpreted to suggest that people are less impaired after AmED, as behavior is the result of coordination of multiple cognitive functions, and reduced impairment on one aspect of cognition may not translate into global improvements.

Weekly Energy Drink Use Is Positively Associated with Delay Discounting and Risk Behavior in a Nationwide Sample of Young Adults

Background: Energy drink use is associated with increased risk behavior among adolescents and college students. This study examined this relationship in a nationwide sample of young adults and also examined relations between energy drink use and delay discounting. Methods: Participants were 874 U.S. adults 18-28 years of age with past 30-day consumption of caffeine and alcohol. Participants completed an online survey of energy drink use, drug use, sexual activity, alcohol misuse (alcohol use disorders identification test [AUDIT]), sensation seeking (four-item Brief Sensation Seeking Scale [BSSS-4]), and delay discounting of monetary rewards and condom use. Results: Over one-third of participants (n = 303) reported consuming energy drinks at least once per week. Weekly energy drink users were more likely than less-than-weekly energy drink users to report a recent history of risk behaviors, including cigarette smoking (56% vs. 28%, p < 0.0001), illicit stimulant use (22% vs. 6%, p < 0.0001), and unprotected sex (63% vs. 45%, p < 0.0001). Covariate-adjusted analyses found that weekly energy drink users did not have significantly higher BSSS-4 scores (3.5 vs. 3.1, p = 0.098), but they had higher mean AUDIT scores (8.0 vs. 4.8, p < 0.0001), and they more steeply discounted delayed monetary rewards. Although weekly energy drink users did not show steeper discounting of delayed condom use, they showed a lower likelihood of using a condom when one was immediately available. Conclusions: This study extends findings that energy drink use is associated with risk behavior, and it is the first study to show that energy drink use is associated with monetary delay discounting.

Young adults who mix alcohol with energy drinks: typology of risk-taking behaviour

INTRODUCTION

Contrary to predictions, several studies have shown that people who consume alcohol mixed with energy drinks (AmED) display low odds of risk-taking during AmED versus alcohol drinking sessions. However, these results are based on treating AmED consumers as a homogeneous group. The aim of the present study was to determine typologies of AmED risk-taking behaviour amongst consumers, as well as identifying correlates of AmED risk-taking class membership.

METHODS

AmED consumers (N=403) completed an online survey where they reported whether they had engaged in risk behaviours in the preceding six months during AmED and alcohol drinking sessions. Latent class models were estimated based on AmED risk-taking data; univariate multinomial logistic regression was conducted to determine correlates of class membership.

RESULTS

A 3-class model was selected based on fit and parsimony, identifying: 1) Low risk-taking consumers (38%): low probability of any AmED risk behaviours; 2) disinhibited intake consumers (48%): high probability of drinking and spending more than intended; and 3) high risk-taking consumers (14%): high probability of most AmED risk behaviours assessed. The latter two groups had significantly higher odds of being male and reporting hazardous alcohol use, more frequent AmED use, greater alcohol and ED intake in AmED sessions, and higher trait impulsivity scores. The latter two groups also reported significantly greater odds of risk-taking behaviours regardless of whether consuming alcohol only or AmED.

CONCLUSIONS

AmED consumers are not a homogeneous group in regard to their risk-taking behaviours post-consumption. High likelihood of risk-taking behaviour in AmED sessions, as well as elevated risk-taking in alcohol drinking sessions, highlights the need for targeted harm minimisation policies and programmes for a significant minority of consumers.

A comprehensive review of the effects of mixing caffeinated energy drinks with alcohol

BACKGROUND

In response to concern about whether mixing caffeinated energy drinks with alcohol (AED) increases alcohol consumption and related harm, and the role of industry in this debate, we conducted a comprehensive review of the research evidence on the effects of AED and documented industry involvement in this research.

METHOD

A systematic review of 6 databases. Studies must have examined the effect of consuming alcohol with energy drinks (ED) or caffeine on alcohol-related outcomes.

RESULTS

62 studies were identified; 29 were experiments, 9 had industry ties (8 with Red Bull GmbH). Young adults who consumed AED drank more alcohol and experienced more alcohol-related harm than other drinkers. There was insufficient evidence to conclude that AED led to increased alcohol consumption or altered the nature of alcohol-related harm. However, AED consumers reported that AED increased stimulation and alertness, offset fatigue from drinking, and facilitated drinking. Experimental research also found that combining ED or caffeine with alcohol increased stimulation and alertness, offset alcohol-related fatigue and increased the desire to keep drinking. It did not change BAC, perceived intoxication, perceived impairment and it did not reverse alcohol-induced impairment on simple psychomotor tasks. Combining ED/caffeine with alcohol reduced alcohol-induced impairment on some but not all aspects of complex tasks. Although few in number, studies with industry ties presented contrary evidence.

CONCLUSION

A growing body of evidence suggests that AED may facilitate drinking and related harms via its effects on intoxication but a causal link needs to be confirmed. The influence of industry involvement in this area of research needs to be monitored.

Self-reported risk-taking behavior during matched-frequency sessions of alcohol versus combined alcohol and energy drinks consumption: does co-ingestion increase risk-taking?

BACKGROUND

Emerging evidence indicates that consumers of alcohol mixed with energy drink (AmED) self-report lower odds of risk-taking after consuming AmED versus alcohol alone. However, these studies have been criticized for failing to control for relative frequency of AmED versus alcohol-only consumption sessions. These studies also do not account for quantity of consumption and general alcohol-related risk-taking propensity. The aims of the present study were to (i) compare rates of risk-taking in AmED versus alcohol sessions among consumers with matched frequency of use and (ii) identify consumption and person characteristics associated with risk-taking behavior in AmED sessions.

METHODS

Data were extracted from 2 Australian community samples and 1 New Zealand community sample of AmED consumers (n = 1,291). One-fifth (21%; n = 273) reported matched frequency of AmED and alcohol use.

RESULTS

The majority (55%) of matched-frequency participants consumed AmED and alcohol monthly or less. The matched-frequency sample reported significantly lower odds of engaging in 18 of 25 assessed risk behaviors in AmED versus alcohol sessions. Similar rates of engagement were evident across session type for the remaining behaviors, the majority of which were low prevalence (reported by <15%). Regression modeling indicated that risk-taking in AmED sessions was primarily associated with risk-taking in alcohol sessions, with increased average energy drink (ED) intake associated with certain risk behaviors (e.g., being physically hurt, not using contraception, and driving while over the legal alcohol limit).

CONCLUSIONS

Bivariate analyses from a matched-frequency sample align with past research showing lower odds of risk-taking behavior after AmED versus alcohol consumption for the same individuals. Multivariate analyses showed that risk-taking in alcohol sessions had the strongest association with risk-taking in AmED sessions. However, hypotheses of increased risk-taking post-AmED consumption were partly supported: Greater ED intake was associated with increased likelihood of specific behaviors, including drink-driving, sexual behavior, and aggressive behaviors in the matched-frequency sample after controlling for alcohol intake and risk-taking in alcohol sessions. These findings highlight the need to consider both personal characteristics and beverage effects in harm reduction strategies for AmED consumers.