Self-reported physiological and psychological side-effects of an acute alcohol and energy drink dose.

OBJECTIVE: There have been repeated calls from health professionals and policy-makers to clarify the side-effects of the increasingly popular consumption trend of alcohol mixed with energy drinks (AmED). There is a dearth of research assessing the differential effects of AmED relative to alcohol by comparing self-reported psychological and physiological outcomes whilst under the influence of these substances. The aim of the present study was to examine the acute effects of a moderate alcohol and energy drink (ED) dose on self-reported psychological and physiological outcomes. METHOD: Using a single-blind, placebo-controlled, crossover design, 28 adults completed four sessions where they were administered: (i) 0.50g/kg alcohol, (ii) 3.57mL/kg ED, (iii) AmED, and (iv) placebo. Participants independently completed the Profile of Mood States and a Somatic Symptom Scale at baseline and at 30 and 125min after beverage administration. RESULTS: Breath alcohol concentration peaked at .068% and .067% in the alcohol and AmED conditions, respectively. There were no interactive alcohol and ED effects on self-reported psychological outcomes. Treatment effects for physiological outcomes generally only related to alcohol or ED administration, with the exception of a moderate magnitude decrease in heart palpitation ratings following alcohol relative to AmED. Decreased muscular tension ratings were evident when the two constituents were consumed separately relative to placebo. CONCLUSIONS: The results provide evidence of few subjective changes in physiological and psychological state after consuming AmED relative to alcohol. The majority of treatment-based changes arose from the independent effects of alcohol or ED, rather than being modified by their interaction. However, research extending into higher dosage domains is required to increase outcome generalisability for consumers in the night-time economy.

The impact of alcohol and energy drink consumption on intoxication and risk-taking behavior.

BACKGROUND: It has been argued that consuming alcohol mixed with energy drinks (AmED) causes a subjective underestimation of intoxication and an increased level of risk-taking behavior. To date, however, there is mixed support for AmED-induced reductions in perceived intoxication, and no objective assessment of risk-taking following AmED consumption. Consequently, the present study aimed to determine the effect of alcohol and energy drink (ED) consumption on subjective measures of intoxication and objective measures of risk-taking. METHODS: Using a placebo-controlled, single-blind, cross-over design, participants (n = 28) attended 4 sessions in which they were administered, in counterbalanced order: 0.5 g/kg alcohol, 3.57 ml/kg ED, AmED, and a placebo beverage. Participants completed the Biphasic Alcohol Effects Scale and a Subjective Effects Scale at baseline and 30 and 125 minutes postbeverage administration; risk-taking was measured using the Balloon Analogue Risk Task (BART). RESULTS: Participants reported greater subjective intoxication, impairment, and sedation after active relative to placebo alcohol consumption, with no interactive AmED effects. However, a significant moderate magnitude increase in stimulation ratings was observed in the AmED relative to alcohol, ED, and placebo conditions. There was no independent effect of alcohol, or interactive effect with ED, on the BART. A significant, yet small magnitude, increase in risk-taking was evident in active relative to placebo ED conditions. CONCLUSIONS: The interactive effect of AmED appears restricted to perceived stimulation, with alcohol-induced increases in subjective intoxication occurring regardless of presence or absence of ED. Engagement in risk-taking behavior was only increased by ED consumption; however, this effect was only of small magnitude; at these doses, alcohol consumption, with or without EDs, did not affect risk-taking. Further research assessing the dose-dependent effects of AmED on objectively measured risk-taking behavior could clarify whether the ED effect increases with higher doses and whether an interactive effect is observed with higher alcohol doses.

The subjective physiological, psychological, and behavioral risk-taking consequences of alcohol and energy drink co-ingestion.

BACKGROUND: The increasingly popular practice among adolescents and young adults of consuming alcohol mixed with energy drinks (AmED) has raised concern regarding potential increases in maladaptive drinking practices, negative psychological and physiological intoxication side effects, and risky behavioral outcomes. Comparison of user types has revealed that AmED users report engaging in more risk-taking behavior relative to alcohol users. However, the comparative likelihood of risk-taking according to session type (i.e., AmED vs. alcohol session) remains relatively unknown. Thus, this study was designed with the aim of establishing the subjective physiological, psychological, and behavioral risk-taking outcomes of AmED consumption relative to alcohol consumption for AmED users drawn from the community. METHODS: Between May and June 2011, 403 Australians aged 18 to 35 who had consumed AmED and alcohol only in the preceding 6 months completed a 10- to 30-minute online survey about their use of these substances. RESULTS: Despite participants consuming a significantly greater quantity of alcohol in AmED sessions compared to alcohol sessions, the odds of participants experiencing disinhibition and engaging in 26 risk behaviors were significantly lower during AmED sessions relative to alcohol sessions. Similarly, the odds of experiencing several physiological (i.e., speech and walking difficulties, nausea, and slurred speech) and psychological (i.e., confusion, exhaustion, sadness) sedation outcomes were less during AmED sessions compared to alcohol sessions. However, the odds of enduring physiological (i.e., heart palpitations, sleep difficulties, agitation, tremors, jolt and crash episodes, and increased speech speed) and psychological (i.e., irritability and tension) outcomes potentially related to overstimulation were significantly greater during AmED sessions than alcohol sessions. CONCLUSIONS: Co-ingestion may provide a double-edged effect. The increased stimulation from energy drinks (EDs) may negate some intoxication-related sedation side effects by increasing alertness. However, it could also lead to negative physiological side effects associated with overstimulation. Notwithstanding any stimulatory effects of EDs, risk and negative effects of excessive alcohol consumption were present in both session types. However, the odds of engaging in risk-taking were less during AmED sessions relative to alcohol sessions. Objective measurement of behavioral risk-taking via laboratory-based measures could confirm the causal relationship between AmED and risk-taking.

Target processing is facilitated by motivationally relevant cues.

The effect that motivationally relevant stimuli have on processes of attentional engagement and disengagement was investigated during two modified peripheral cueing paradigms. Sexual, mutilation, threatening, and neutral stimuli served as peripheral cues in both experiments. Responses were made to target location in Experiment 1 (N=19 female) and target identity in Experiment 2 (N=18 female). As indexed by enhanced target-evoked P1 and P3b component amplitudes, target processing was facilitated by the presentation of sexual and mutilation stimuli in both experiments. This facilitation in response to targets cued by sexual and mutilation stimuli occurred regardless of whether cueing was valid or invalid as demonstrated by the non-significant cue validity x picture-type interaction. As such, the processes of attentional engagement (as inferred by responses to validly cued targets) and attentional disengagement (as inferred by responses to invalidly cued targets) were not differentially affected by the motivational relevance of the preceding cue. These results indicate that in a non-clinical sample, participants can shift attention rapidly to process information following the onset of motivationally relevant stimuli at attended (valid) and unattended (invalid) locations and that target processing is facilitated by the presence of appetitive and aversive cues.

Patterns of use and motivations for consuming alcohol mixed with energy drinks.

Use of alcohol mixed with energy drinks (AmED) is an increasingly prevalent trend. However, recent research has suggested that AmED use may result in increased alcohol consumption and engagement in risk behavior postingestion. Although the majority of research has been focused on AmED use outcomes, there is a current paucity of data on the patterns of AmED use and motives for consumption. Four hundred and three participants from an Australian community sample (n = 244 women) ages 18-35 who had consumed alcohol mixed simultaneously with energy drinks (ED) in the preceding 6 months completed an online survey regarding use of EDs, alcohol, and AmED. Although AmED sessions occurred relatively infrequently compared to alcohol sessions, the alcohol and ED quantity consumed in AmED sessions was significantly greater than recommended intake. Reports of AmED use context indicated that participants typically consumed AmED while engaging in heavy drinking in public venues. However, the primary motives for AmED use related to the situational context of use, functional and hedonistic outcomes, as well as the pleasurable taste; few participants reported using AmED to increase alcohol intake, to mask intoxication, to hide alcohol's flavor, or to simulate an illicit drug "high." AmED users may be coingesting in a context and at a quantity that enhances the possibility of risky alcohol outcomes, despite predominantly consuming AmED for the taste and the functional and hedonistic outcomes. Strong endorsement of motives relating to ease of access and low cost price suggests that alcohol policy reform in relation to licensing restrictions may be necessary to minimize the risk of harm.

Electro-cortical implicit race bias does not vary with participants' race or sex.

Earlier research found evidence for electro-cortical race bias towards black target faces in white American participants irrespective of the task relevance of race. The present study investigated whether an implicit race bias generalizes across cultural contexts and racial in- and out-groups. An Australian sample of 56 Chinese and Caucasian males and females completed four oddball tasks that required sex judgements for pictures of male and female Chinese and Caucasian posers. The nature of the background (across task) and of the deviant stimuli (within task) was fully counterbalanced. Event-related potentials (ERPs) to deviant stimuli recorded from three midline sites were quantified in terms of mean amplitude for four components: N1, P2, N2 and a late positive complex (LPC; 350-700 ms). Deviants that differed from the backgrounds in sex or race elicited enhanced LPC activity. These differences were not modulated by participant race or sex. The current results replicate earlier reports of effects of poser race relative to background race on the LPC component of the ERP waveform. In addition, they indicate that an implicit race bias occurs regardless of participant's or poser's race and is not confined to a particular cultural context.

An ERP study of age-related differences in the central cost of interlimb coordination.

The study investigated event-related EEG potentials during concurrent performance of interlimb coordination and visual oddball tasks by younger and older adults. Coordination task difficulty was equated between age groups by allowing participants to perform the task at self-determined frequencies. The amplitude of the P3b component of the event-related potentials (ERPs) elicited by visual task targets showed a different pattern across midline sites (Fz, Cz, Pz) for younger and older adults. While younger adults showed a parietal maximum, P3b amplitudes in older adults did not differ across midline site, with lower amplitudes at central and parietal sites than younger adults but higher amplitude at the frontal site. Younger adults also had significantly shorter P3b latency than older adults. The results suggest that older adults may rely more on cognitive control of their movements than younger adults.

Affective picture processing and motivational relevance: arousal and valence effects on ERPs in an oddball task.

There are two dominant theories of affective picture processing; one that attention is more deeply engaged by motivationally relevant stimuli (i.e., stimuli that activate both the appetitive and aversive systems), and two that attention is more deeply engaged by aversive stimuli described as the negativity bias. In order to identify the theory that can best account for affective picture processing, event-related potentials (ERPs) were recorded from 34 participants during a modified oddball paradigm in which levels of stimulus valence, arousal, and motivational relevance were systematically varied. Results were partially consistent with motivated attention models of emotional perception, as P3b amplitude was enhanced in response to highly arousing and motivationally relevant sexual and unpleasant stimuli compared to respective low arousing and less motivationally relevant stimuli. However P3b amplitudes were significantly larger in response to the highly arousing sexual stimuli compared to all other affective stimuli, which is not consistent with either dominant theory. The current study therefore highlights the need for a revised model of affective picture processing and provides a platform for further research investigating the independent effects of sexual arousal on cognitive processing.