The consumption of alcohol mixed with energy drinks (AmED) has become a popular and controversial practice among young people. Increased rates of impaired driving and injuries have been associated with AmED consumption. The purpose of this study was to examine if the consumption of AmED alters cognitive processing and subjective measures of intoxication compared with the consumption of alcohol alone. Eighteen participants (9 men and 9 women) attended 4 test sessions where they received one of 4 doses in random order (0.65 g/kg alcohol, 3.57 ml/kg energy drink, AmED, or a placebo beverage). Performance on a psychological refractory period (PRP) task was used to measure dual-task information processing and performance on the Purdue pegboard task was used to measure simple and complex motor coordination following dose administration. In addition, various subjective measures of stimulation, sedation, impairment, and level of intoxication were recorded. The results indicated that alcohol slowed dual-task information processing and impaired simple and complex motor coordination. The co-administration of the energy drink with alcohol did not alter the alcohol-induced impairment on these objective measures. For subjective effects, alcohol increases various ratings indicative of feelings of intoxication. More importantly, co-administration of the energy drink with alcohol reduced perceptions of mental fatigue and enhanced feelings of stimulation compared to alcohol alone. In conclusion, AmED may contribute to a high-risk scenario for a drinker. The mix of behavioral impairment with reduced fatigue and enhanced stimulation may lead AmED consumers to erroneously perceive themselves better able to function than is actually the case.
alcohol; energy drink; dual-task interference; mental fatigue; stimulation
Previous research has shown that social drinkers continue to show attentional bias towards alcohol-related stimuli even after consuming a moderate dose of alcohol. In contrast, little is known about how alcohol acutely affects attentional bias in groups at risk to develop alcohol-related problems, such as adults with attention-deficit/hyperactivity disorder (ADHD). Such individuals may show increased attentional bias following alcohol relative to nonclinical controls. The present study tested this hypothesis by examining acute alcohol effects on attentional bias in 20 social drinkers with ADHD and 20 social drinkers with no history of ADHD. Participants performed a visual-probe task after receiving the following doses of alcohol: 0.64 g/kg, 0.32 g/kg, and 0.0 g/kg (placebo). Those in the ADHD group showed increased attentional bias under active alcohol doses, whereas attentional bias was similar across doses in the control group. Attentional bias predicted ad libitum alcohol consumption during a taste-rating session. This relation was observed only in the ADHD group. These findings indicate that an acute alcohol dose increases attentional bias in adults with ADHD. Further, attentional bias appears to be a predictor of ad libitum consumption in this group.
Attentional bias; ADHD; Alcohol; Ad libitum consumption; At-risk drinkers
Separate cognitive processes govern the inhibitory control of manual and oculomotor movements. Despite this fundamental distinction, little is known about how these inhibitory control processes relate to more complex domains of behavioral functioning. This study sought to determine how these inhibitory control mechanisms relate to broadly defined domains of impulsive behavior. Thirty adults with attention-deficit/hyperactivity disorder (ADHD) and 28 comparison adults performed behavioral measures of inhibitory control and completed impulsivity inventories. Results suggest that oculomotor inhibitory control, but not manual inhibitory control, is related to specific domains of self-reported impulsivity. This finding was limited to the ADHD group; no significant relations between inhibitory control and impulsivity were found in comparison adults. These results highlight the heterogeneity of inhibitory control processes and their differential relations to different facets of impulsivity.
impulsivity; inhibitory control; manual; oculomotor; ADHD
Heavy episodic or “binge” drinking is commonly defined as drinking 4–5 drinks per occasion (5/4 definition) or drinking that results in a blood alcohol concentration (BAC) of 0.08%. The present study compared the validity of each binge definition as an indicator of at-risk, problem drinking. 251 college students were classified as non-binge drinkers or as binge drinkers based on the 5/4 definition or the 0.08% BAC definition. The two definitions of binge drinking were examined in terms of their sensitivity and specificity as indicators of alcohol-related problems as determined by scores on the Alcohol Use Disorders Identification Test (AUDIT). Over half the sample (56%) were at-risk drinkers according to the AUDIT. The 0.08% definition detected only one-half of these individuals. Gender differences were also evident. Female binge drinkers actually achieved significantly higher estimated BACs per episode than their male binge drinking counterparts. The findings suggest that drinking to a sub-threshold BAC (i.e., < 0.08%) is not sufficient to avoid alcohol-related problems, and that total quantity (i.e., total standard drinks) per occasion might contribute to risk independent of the BAC achieved during drinking episodes. The findings also highlight the importance of considering frequency of consumption in determining risky drinking versus relying solely on quantity measures.
Recognition of the risks associated with alcohol intoxication and driver distraction has led to a wealth of simulated driving research aimed at studying the adverse effects of each of these factors. Research on driving has moved beyond the individual, separate examination of these factors to the examination of potential interactions between alcohol intoxication and driver distraction. In many driving situations, distractions are commonplace and might have little or no disruptive influence on primary driving functions. Yet, such distractions might become disruptive to a driver who is intoxicated.
The present study examined the interactive impairing effects of alcohol intoxication and driver distraction on simulated driving performance in 40 young adult drivers using a divided attention task as a distracter activity. The interactive influence of alcohol and distraction was tested by having drivers perform the driving task under four different conditions: 0.65 g/kg alcohol; 0.65 g/kg alcohol + divided attention; placebo; and placebo + divided attention.
As hypothesized, divided attention had no impairing effect on driving performance in sober drivers. However, under alcohol, divided attention exacerbated the impairing effects of alcohol on driving precision.
Alcohol and distraction continue to be appropriate targets for research into ways to reduce the rates of driving-related fatalities and injuries. Greater consideration of how alcohol and distraction interact to impair aspects of driving performance can further efforts to create prevention and intervention measures to protect drivers, particularly young adults.
Alcohol; Distraction; Divided Attention; Driving
There has been a dramatic rise in the consumption of alcohol mixed with energy drinks (AmED) in young people. AmEDs have been implicated in risky drinking practices and greater accidents and injuries have been associated with their consumption. Despite the increased popularity of these beverages (e.g., Red Bull and vodka), there is little laboratory research examining how the effects of AmED differ from alcohol alone. This experiment was designed to investigate if the consumption of AmED alters neurocognitive and subjective measures of intoxication compared with the consumption of alcohol alone.
Participants (n=56) attended one session where they were randomly assigned to receive one of four doses (0.65 g/kg alcohol, 3.57 ml/kg energy drink, AmED or a placebo beverage). Performance on a cued go/no-go task was used to measure the response of inhibitory and activational mechanisms of behavioral control following dose administration. Subjective ratings of stimulation, sedation, impairment and level of intoxication were recorded.
Alcohol alone impaired both inhibitory and activational mechanisms of behavioral control, as evidenced by increased inhibitory failures and increased response times compared to baseline performance. Coadministration of the energy drink with alcohol counteracted some of the alcohol-induced impairment of response activation, but not response inhibition. For subjective effects, alcohol increased ratings of stimulation, feeling the drink, liking the drink, impairment and level of intoxication and alcohol decreased the rating of ability to drive. Coadministration of the energy drink with alcohol increased self-reported stimulation, but resulted in similar ratings of the other subjective effects as when alcohol was administered alone.
An energy drink appears to alter some of alcohol’s objective and subjective impairing effects, but not others. Thus AmEDs may contribute to a high risk scenario for the drinker. The mix of impaired behavioral inhibition and enhanced stimulation is a combination that may make AmED consumption riskier than alcohol consumption alone.
alcohol; energy drink; behavioral control; reaction time; stimulation
Increased intra-individual variability in response time (RTSD) has been observed reliably in ADHD and is often used as a measure of inattention. RTSD is assumed to reflect attentional lapses and distractibility, though evidence for the validity of this connection is lacking. We assessed whether RTSD is an indicator of inattention by comparing RTSD on the stop-signal task (SST) to performance on the Delayed Oculomotor Response (DOR) Task, a measure of distractibility. Participants included 30 adults with ADHD and 28 controls. Participants completed the SST and the DOR task, which measured subjects’ ability to maintain attention and avoid distraction by inhibiting reflexive saccades toward distractors. On the SST, the ADHD group was slower to inhibit than controls, indicating poorer inhibitory control in ADHD. The ADHD group also displayed slower RTs, greater RTSD, and more omission errors. On the DOR task, the ADHD group displayed more premature saccades (i.e., greater distractibility) than controls. Greater variability in RT was associated with increased distraction on the DOR task but only in ADHD participants. Results suggest that RTSD is linked to distractibility among adults with ADHD and support the use of RTSD as a valid measure of inattention in ADHD.
ADHD; adults; variable attention; eye movements
Researchers in the cognitive sciences recognize a fundamental distinction between automatic and intentional mechanisms of inhibitory control. The use of eye-tracking tasks to assess selective attention has led to a better understanding of this distinction in specific populations such as children with attention-deficit/hyperactivity disorder (ADHD). This study examined automatic and intentional inhibitory control mechanisms in adults with ADHD using a saccadic interference (SI) task and a delayed ocular response (DOR) task. Thirty adults with ADHD were compared to 27 comparison adults on measures of inhibitory control. The DOR task showed that adults with ADHD were less able than comparison adults to inhibit a reflexive saccade towards the sudden appearance of a stimulus in the periphery. However, SI task performance showed that the ADHD group did not differ significantly from the comparison group on a measure of automatic inhibitory control. These findings suggest a dissociation between automatic and intentional inhibitory deficits in adults with ADHD.
ADHD; inhibition; automatic; intentional
The degree to which distinct behavioral components of impulsivity predict alcohol consumption is as yet not well-understood. Further, the possibility that this relation might be more pronounced in groups characterized by heightened impulsivity (i.e., individuals with ADHD) has not been tested.
The current study examined the degree to which three specific behavioral components of impulsivity (i.e., poor response inhibition, poor attentional inhibition, and increased risk-taking) were associated with quantity and frequency of alcohol consumption in a group of young adult social drinkers with ADHD (n = 33) and in a comparison control group (n = 21). Participants performed the delayed ocular return task (attentional inhibition), the cued go/no-go task (behavioral inhibition), and the Balloon Analogue Risk Task (risk-taking).
Both poor behavioral inhibition and greater risk-taking were related to greater quantity of consumption in the entire sample, whereas poor attentional inhibition was related to greater quantity specifically among those with ADHD. By contrast, only risk-taking was associated with frequency of consumption, and this was found specifically in the control group.
These findings provide important information regarding the potential role of distinct behavioral components of impulsivity in drinking behavior, and highlight unique relevance of attentional impairments to drinking behavior in those with ADHD.
behavioral impulsivity; alcohol consumption; ADHD
Moderate doses of alcohol impair response inhibition and slow response activation, and some recent work has shown that during a single dose, response inhibition recovers from the impairing effects of alcohol more slowly than response activation. Evidence for a possible lag in tolerance development to inhibitory versus activational mechanisms suggests that as blood alcohol declines, drinkers' response inhibition might continue to be impaired despite having an unimpaired ability to activate responses; however, this effect has not been studied across repeated doses.
The present study examined how cross-session tolerance to the impairing effects of alcohol develops differentially between response activation and inhibition.
Thirty-two healthy adults performed a cued go/no-go task that measured response activation and inhibition. The study tested the degree to which response activation and inhibition developed acute and cross-session tolerances to a moderate dose of alcohol (0.65 g/kg) administered twice on separate days.
Alcohol slowed response activation and decreased response inhibition during both administrations. Response activation displayed acute tolerance to alcohol impairment during both administrations and cross-session tolerance from the first to second administration. By contrast, response inhibition showed no acute or cross-session tolerance.
Biased recovery of response activation over inhibition during a single dose and as doses are repeated could contribute to some of the impulsive behavior commonly observed under alcohol.
Alcohol; Inhibition; Activation; Tolerance; Response Conflict; Go/no-go task
Although stimulants are generally associated with enhanced information processing, reports of stimulant effects on behavioral functions that rely on inhibitory processes have been inconsistent. The present research tested the joint effects of d-amphetamine on information processing and inhibitory control in healthy adults (N = 22) with no reported history of illicit stimulant use or drug dependence. Information processing was measured by a rapid information processing (RIP) task and inhibitory control was measured using a stop-signal task. Performance was measured in response to 15 mg/70 kg, 7.5 mg/70 kg, and 0 mg/70 mg (placebo) doses of d-amphetamine, administered double-blind in a randomized, within-subjects design. Results showed that d-amphetamine improved information processing in a dose-dependent manner. By contrast, no enhancement of response inhibition was observed. Stimulant effects were also observed in physiological and subjective effects measures. The findings indicate that a stimulant drug can enhance aspects of cognitive functioning without producing a concomitant improvement in inhibitory control of behavior. The findings highlight the complex nature of stimulant effects on human behavior and the utility of performance tasks as models of complex behavioral and cognitive functions.
d-Amphetamine; Response inhibition; Information processing; ADHD; Human
While the personality dimensions of novelty seeking and sensation seeking are associated with drug abuse vulnerability, the mechanisms associated with this vulnerability remain obscure.
This study examined the behavioral effects of d-amphetamine in healthy volunteers scoring in the upper and lower quartiles based on age- and gender-adjusted population norms on the impulsive Sensation-Seeking Scale (SSS) of the Zuckerman–Kuhlman personality questionnaire (ZKPQ).
Participants completed 7-day outpatient studies examining the subjective, performance, and cardiovascular effects of d-amphetamine (0, 7.5, and 15 mg/70 kg, p.o.) under double-blind conditions according to a randomized block design. Performance tasks included behavioral measures of impulsivity, including attention, inhibition, and risk-taking behavior.
No differences in baseline performance or d-amphetamine effects on measures of attention, inhibition, and risk-taking behavior were observed. High impulsive sensation seekers reported greater increases on several subjective report measures associated with drug abuse potential, including visual analog scales feel drug, like drug, and high.
Healthy adults scoring in the top quartile on the population of the impulsive SSS of the ZKPQ may be vulnerable to the abuse potential of d-amphetamine.
d-amphetamine; Sensation-seeking status; Vulnerability; Subjective effects; Performance effects; Abuse potential
The current pair of experimental studies sought to further validate the role of positive urgency (acting rashly when in an extreme positive emotional state) as a risk factor for impulsive and maladaptive behavior. Previous research has supported the use of emotion-based dispositions to rash action in predicting a wide range of maladaptive acts. However, that research was conducted in the field and relied on self-reported behavior, thus lacking tight experimental controls and direct observation of risky behaviors. In the two experimental studies described here, we found that, among college students, (1) positive urgency significantly predicted negative outcomes on a risk-taking task following a positive mood manipulation (n = 94), and (2) positive urgency significantly predicted increases in beer consumption following positive mood induction (n = 33). Positive urgency’s role was above and beyond previously identified risk factors; these findings, combined with prior cross-sectional and longitudinal field studies, provide support for the role of positive urgency in rash action.
This study examined the classification accuracy of the UPPS Impulsive Behavior Scale (UPPS) in discriminating several attention deficit/hyperactivity disorder (ADHD) subtypes, including predominantly inattentive type (ADHD/I), combined type (ADHD/C), and combined type with behavioral problems (ADHD/ODD), between each other and a non-ADHD control group using logistic regression analyses. The sample consisted of 88 children ranging in age from 9.0 years to 12.8 years, with a mean of 10.9 years. Children were predominantly male (74%) and Caucasian (86%) and in grades 3–7. Results indicated that the UPPS performed well in classifying ADHD subtypes relative to traditional diagnostic measures. In addition, analyses indicated that differences in symptoms between subtypes can be explained by specific pathways to impulsivity. Implications for the assessment of ADHD and conceptual issues are discussed.
ADHD; Impulsivity; UPPS; ADHD subtypes
Visual probe tasks are often used to measure attentional bias (AB) toward alcohol-related images in drinkers, but little is known about the effect of the properties of the images used in this task, specifically, image complexity.
AB was examined in a group of adult drinkers (n = 25). Two measures of attentional bias were obtained from a modified visual probe task. First, a traditional dot probe detection task measured attentional bias in drinkers based on their reaction times to probes replacing neutral and alcohol-related images. Second, an eye-tracking measure was applied to this task to directly assess the drinkers' eye gazes to the alcohol-related and neutral images. The effect of image complexity was examined by comparing AB toward images classified as simple and complex.
Results showed that drinkers only displayed AB toward simple alcohol-related images as measured by both probe RT and fixation times.
These findings suggest that complex alcohol-related images might be less effective at capturing drinkers' attention and could result in less attentional bias when used in visual probe tasks.
Alcohol impairs inhibitory control, and it alters implicit alcohol cognitions including attentional bias and implicit associations. These effects are seen after doses of alcohol which do not lead to global impairments in cognitive performance. We review studies which demonstrate that the effects of alcohol on inhibitory control are associated with the ability of alcohol to prime alcohol-seeking behavior. We also hypothesize that alcohol-induced changes in implicit alcohol cognitions may partially mediate alcohol-induced priming of the motivation to drink. Based on contemporary theoretical models and conceptualizations of executive function, impulsivity, and the motivational salience of alcohol-related cues, we speculate on other aspects of cognition that may underlie alcohol’s effects on alcohol seeking. Inconsistencies in existing research and priorities for future research are highlighted, including dose effects and the potential interactions between chronic heavy drinking and the acute effects of alcohol on these cognitive processes.
Inhibitory Control; Attentional Bias; Automatic Alcohol Associations; Priming
Aims: Considerable laboratory research indicates that moderate doses of alcohol impair a broad range of skilled activities related to driving performance in young adults. Although laboratory studies show that the intensity of impairment is generally dependent on the blood alcohol concentration, some reviews of this literature suggest that women might be more sensitive to the impairing effects of alcohol than men. The present study tested this hypothesis. Methods: Drawing on data from previous experiments in our laboratory, we compared men and women in terms of the degree to which a challenge dose of alcohol (0.65 g/kg) impaired their simulated driving performance and measures of three separate behavioral and cognitive functions important to driving performance: motor coordination, speed of information processing and information-processing capacity. Results: Alcohol significantly impaired all aspects of performance. Moreover, women displayed greater impairment than men on all behavioral tests and also reported higher levels of subjective intoxication compared with men. Conclusions: Both biological and social–cultural factors have been implicated in gender differences in the behavioral responses to alcohol. The current evidence of heightened sensitivity to alcohol in women highlights the need for better understanding the biological and environmental factors underlying this gender difference.
Sensation-seeking is a personality characteristic that has been associated with drug abuse. Some evidence suggests that sensation-seekers might experience increased rewarding effects from drugs of abuse, possibly contributing to the association between sensation-seeking and risk for drug abuse. The present study examined the effects of three doses of alcohol (0.0 g/kg, 0.45 g/kg, and 0.65 g/kg) on inhibitory control, information processing, and subjective ratings in a group of high sensation-seekers and a group of low sensation-seekers (N = 20). Inhibitory control was measured by a cued go/no-go task and speed of information processing was assessed by the Rapid Information Processing (RIP) task. Alcohol impaired inhibitory control and information processing. Group differences were also observed. Compared with their low sensation-seeking counterparts, high sensation-seekers demonstrated increased sensitivity to the subjective rewarding effects of alcohol and a poorer degree of inhibitory control that was further impaired by alcohol. The findings highlight reward- and cognitive-based mechanisms by which sensation-seeking could operate to increase risk for alcohol abuse.
Alcohol; Inhibitory Control; Sensation-Seeking; Information Processing
The acute impairing effects of alcohol on inhibitory control have been well documented in healthy drinkers. By contrast, little is known about alcohol effects in individuals with disorders characterized by poor impulse control, such as those with ADHD. Alcohol could produce greater inhibitory impairment in these individuals. The present study tested this hypothesis in adults with ADHD (N = 10) and controls (N = 12) using the cued go/no-go task. The task requires quick responses to go targets and suppression of responses to no-go targets following the presentation of cues. Prior research on healthy adults shows that valid cues can protect against alcohol impairment (Marczinski & Fillmore, 2003). Performance was tested under 3 doses of alcohol: 0.65 g/kg, 0.45 g/kg, and 0.0 g/kg (placebo). Alcohol dose-dependently increased inhibitory failures in controls in the invalid, but not the valid, cue condition. By contrast, those with ADHD displayed significant alcohol impairment regardless of cue condition. Thus, unlike controls, valid cues offered little protection from the disinhibiting effects of alcohol in drinkers with ADHD, suggesting an increased sensitivity to alcohol-impairment of inhibitory control.
ADHD; alcohol; inhibitory control; cues
Automobile crash reports show that up to 40% of fatal crashes in the United States involve alcohol and that younger drivers are over-represented. Alcohol use among young drivers is associated with impulsive and risky driving behaviors, such as speeding, which could contribute to their over-representation in alcohol-related crash statistics. Recent laboratory studies show that alcohol increases impulsive behaviors by impairing the drinker’s ability to inhibit inappropriate actions and that this effect can be exacerbated in conflict situations where the expression and inhibition of behavior are equally motivating. The present study tested the hypothesis that this response conflict might also intensify the disruptive effects of alcohol on driving performance. Fourteen subjects performed a simulated driving and a cued go/no-go task that measured their inhibitory control. Conflict was motivated in these tasks by providing equal monetary incentives for slow, careful behavior (e.g., slow driving, inhibiting impulses) and for quick, abrupt behavior (fast driving, disinhibition). Subjects were tested under two alcohol doses (0.65 g/kg and a placebo) that were administered twice: when conflict was present and when conflict was absent. Alcohol interacted with conflict to impair inhibitory control and to increase risky and impaired driving behavior on the drive task. Also, individuals whose inhibitory control was most impaired by alcohol displayed the poorest driving performance under the drug. The study demonstrates potentially serious disruptions to driving performance as a function of alcohol intoxication and response conflict, and points to inhibitory control as an important underlying mechanism.
Alcohol; Driving; Impulsivity; Response Conflict
This article summarizes a symposium organized and cochaired by Maria Testa and presented at the 2005 Annual Meeting of the Research Society on Alcoholism, in Santa Barbara, California. The symposium explored issues relevant to understanding the function of placebo conditions and to interpreting placebo effects. Cochair Mark Fillmore began with an overview of the use of placebo conditions in alcohol research, focusing on methodological issues. Jeanette Norris and her colleagues conducted a review of studies examining placebo conditions among women. They conclude that expectancy effects are limited to a few domains. Maria Testa and Antonia Abbey presented papers suggesting that placebo manipulations may result in unanticipated compensatory effects in actual or hypothetical social situations. That is, placebo participants may compensate for anticipated cognitive impairment through vigilant attention to situational cues. John Curtin’s research suggests that the compensatory strategies of placebo participants appear to involve a sensitization of evaluative control, resulting in improved performance. Kenneth Leonard provided concluding remarks on the meaning of placebo effects and the value of placebo conditions in research.
Alcohol Drinking; Placebo Effect; Methods