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1.  Individual differences in acute alcohol impairment of inhibitory control predict ad libitum alcohol consumption 
Psychopharmacology  2008;201(3):315-324.
Research has begun to examine how acute cognitive impairment from alcohol could contribute to alcohol abuse. Specifically, alcohol-induced impairment of inhibitory control could compromise the drinker’s ability to stop the self-administration of alcohol, increasing the risk of binge drinking.
The present study was designed to test this hypothesis by examining the relation between acute alcohol impairment of inhibitory control and alcohol consumption during a single drinking episode.
Materials and methods
Twenty-six healthy adults performed a cued go/no-go task that measured inhibitory control. The study tested the degree to which their inhibitory control was impaired by a moderate dose of alcohol (0.65 g/kg) versus a placebo and the extent to which individual differences in this impairment predicted levels of alcohol consumption as assessed by ad lib drinking in the laboratory.
In accord with the hypothesis, greater impairment of inhibitory control from alcohol was associated with increased ad lib consumption.
Acute impairment of inhibitory control might be an important cognitive effect that contributes to abuse in addition to the positive rewarding effects of the drug.
PMCID: PMC4310478  PMID: 18758758
Alcohol; Inhibition; Ad lib consumption; Cued go/no-go task; Neurocognitive mechanisms; Abuse potential
2.  Acute tolerance to alcohol impairment of behavioral and cognitive mechanisms related to driving: drinking and driving on the descending limb 
Psychopharmacology  2011;220(4):697-706.
Alcohol effects on behavioral and cognitive mechanisms influence impaired driving performance and decisions to drive after drinking (Barry 1973; Moskowitz and Robinson 1987). To date, research has focused on the ascending limb of the blood alcohol curve, and there is little understanding of how acute tolerance to impairment of these mechanisms might influence driving behavior on the descending limb.
To provide an integrated examination of the degree to which alcohol impairment of motor coordination and inhibitory control contributes to driving impairment and decisions to drive on the ascending and descending limbs of the blood alcohol curve.
Social-drinking adults (N=20) performed a testing battery that measured simulated driving performance and willingness to drive, as well as mechanisms related to driving: motor coordination (grooved pegboard), inhibitory control (cued go/no-go task), and subjective intoxication. Performance was tested in response to placebo and a moderate dose of alcohol (0.65 g/kg) twice at comparable blood alcohol concentrations: once on the ascending limb and again on the descending limb.
Impaired motor coordination and subjective intoxication showed acute tolerance, whereas driving performance and inhibitory control showed no recovery from impairment. Greater motor impairment was associated with poorer driving performance under alcohol, and poorer inhibitory control was associated with more willingness to drive.
Findings suggest that acute tolerance to impairment of motor coordination is insufficient to promote recovery of driving performance and that the persistence of alcohol-induced disinhibition might contribute to risky decisions to drive on the descending limb.
PMCID: PMC4307943  PMID: 21960182
Acute tolerance; Driving; Inhibition; Motor control; Subjective intoxication
3.  Simulated Driving Performance of Adults with ADHD: Comparisons with Alcohol Intoxication 
Previous research has demonstrated that adults with ADHD are more likely to experience driving-related problems, which suggests that they may exhibit poorer driving performance. However, direct experimental evidence of this hypothesis is limited. The current study involved two experiments that evaluated driving performance in adults with ADHD in terms of the types of driving decrements typically associated with alcohol intoxication. Experiment 1 compared the simulated driving performance of 15 adults with ADHD to 23 adult control participants, who performed the task both while sober and intoxicated. Results showed that sober adults with ADHD exhibited decrements in driving performance compared to sober controls, and that the profile of impairment for the sober ADHD group did in fact resemble that of intoxicated drivers at the BAC level for legally impaired driving in the United States. Driving impairment of the intoxicated individuals was characterized by greater deviation of lane position, faster and more abrupt steering maneuvers, and increased speed variability. Experiment 2 was a dose-challenge study in which 8 adults with ADHD and 8 controls performed the driving simulation task under three doses of alcohol: 0.65 g/kg, 0.45 g/kg, and 0.0 g/kg (placebo). Results showed that driving performance in both groups was impaired in response to alcohol, and that individuals with ADHD exhibited generally poorer driving performance than did controls across all dose conditions. Together the findings provide compelling evidence to suggest that the cognitive and behavioral deficits associated with ADHD might impair driving performance in such a manner as to resemble that of an alcohol intoxicated driver. Moreover, alcohol might impair the performance of drivers with ADHD in an additive fashion that could considerably compromise their driving skill even at blood alcohol concentrations below the legal limit.
PMCID: PMC4305387  PMID: 18540785
4.  The Effects of Preresponse Cues on Inhibitory Control and Response Time in Adults with ADHD 
Journal of attention disorders  2013;10.1177/1087054713495737.
To examine the effects of preresponse cues on behavioral control in adults with attention-deficit/hyperactivity disorder (ADHD).
Eighty-eight adults with ADHD and 67 adults with no history of ADHD completed a cued go/no-go task. This task requires participants to respond or inhibit a response to go and no-go targets, respectively, and preresponse cues provide participants with predictive information about the upcoming target.
Overall, participants with ADHD made more inhibitory failures and responded more slowly than controls. These group differences were only present in the valid-cue condition, and there were no significant group differences in the invalid-cue conditions.
These findings suggest that adults with ADHD are less able to utilize predictive environmental information to facilitate behavioral control.
PMCID: PMC4026333  PMID: 23881558
5.  Alcohol-related stimuli reduce inhibitory control of behavior in drinkers 
Psychopharmacology  2012;222(3):489-498.
Poor behavioral control and heightened attentional bias toward alcohol-related stimuli have independently received considerable attention in regard to their roles in alcohol abuse. Theoretical accounts have begun to speculate as to potential reciprocal interactions between these two mechanisms that might promote excessive alcohol consumption, yet experimental evidence is lacking.
The objective of the study was to integrate these two lines of research through the development of a novel laboratory task that examines the degree to which alcohol cues serve to disrupt mechanisms of behavioral control.
Fifty adult drinkers were recruited to perform the attentional bias–behavioral activation (ABBA) task. The ABBA task, an adaptation of traditional cued go/no-go tasks, is a reaction time model that measures the degree to which alcohol-related stimuli can increase behavioral activation of a drinker and reduce the ability to inhibit inappropriate responses. Participants also completed a novel measure of attentional bias, the scene inspection paradigm (SIP), that measures fixation time on alcohol content imbedded in complex scenes.
As hypothesized, the proportion of inhibitory failures on the ABBA task was significantly higher following alcohol images compared to neutral images. Correlational analyses showed that heightened attentional bias on the SIP was associated with greater response activation following alcohol images on the ABBA task.
These findings suggest that alcohol stimuli serve to disrupt mechanisms of behavioral control, and that heightened attentional bias is associated with greater disruption of control mechanisms following alcohol images.
PMCID: PMC4301262  PMID: 22358851
Alcohol; Behavioral control; Attentional bias; Response activation; Inhibition
Drug and alcohol dependence  2013;133(2):10.1016/j.drugalcdep.2013.08.004.
Cocaine users show impaired inhibitory control on cued go/no-go tasks and attention bias to drug-related images in eye-tracking tasks. The results of a previous study suggested that there is a relationship between inhibitory control and attention bias in alcohol drinkers such that the presentation of alcohol-related images as a go cue in a cued go/no-go task significantly impaired inhibitory control compared to neutral images as a go cue. The present study determined the generality of these previous findings by assessing inhibitory control in cocaine users utilizing a modified cued go/no-go task with cocaine or neutral images as the cues.
Non-treatment seeking cocaine users (N=30) completed the modified task after completing detailed measures of demographics and drug use. Participants were matched on basic demographic factors and were assigned to groups in which they saw either a cocaine or neutral image as the go cue.
Participants assigned to the cocaine image go cue condition had a significantly higher proportion of inhibitory failures to the no-go target than their counterparts assigned to the neutral cue condition, but there were no group differences on reaction time (i.e., accuracy was not traded for speed).
Cocaine users were less able to inhibit pre-potent responses when a cocaine-related image served as the go cue than when a neutral image served as the go cue, consistent with previous research in alcohol users. The outcomes suggest that cocaine-related cues produce disinhibition, perhaps contributing to the high incidence of relapse or continued cocaine use.
PMCID: PMC3818419  PMID: 24004904
cocaine; response inhibition; inhibitory control; behavioral control; response activation
7.  Can the use of multiple stop signals reduce the disinhibiting effects of alcohol? 
Alcoholism, clinical and experimental research  2013;37(11):10.1111/acer.12166.
Research has consistently demonstrated that alcohol impairs the ability to divide attention across two or more stimuli. However, under certain circumstances, the presentation of multiple stimuli can actually facilitate performance. The “redundant signal effect” (RSE) refers to the phenomenon by which individuals respond more quickly and accurately when information is presented as redundant, bimodal stimuli (e.g., visually and aurally), rather than as a single stimulus presented to either modality alone. Recent work has shown that response time (RT) to redundant signals is hastened under alcohol, ameliorating the slowing effects of the drug. However, no research has examined whether RSE can reduce the impairing effects of alcohol on the ability to inhibit behavior.
This study examined whether the impairing effects of alcohol on inhibitory control might be altered by the presentation of redundant inhibitory signals. Inhibitory control was assessed by a go/no-go task which included single and redundant inhibitory signals. Performance was tested following placebo (0.0 g/kg) and alcohol (0.65 g/kg). The effect of redundant activation signals on alcohol impairment of response activation was also measured.
The results showed evidence for RSE on the activation of behavior, but not for inhibitory control. Compared with placebo, alcohol slowed RT and reduced response inhibition. Redundant signals had a robust speeding effect on RT, even following alcohol. By contrast, redundant signals failed to improve inhibitory control following placebo or alcohol.
These findings have important implications for understanding how drinkers respond to multimodal signals in their everyday environments and highlight the vulnerability of inhibitory control to alcohol’s impairing effects.
PMCID: PMC3812342  PMID: 23906541
alcohol; redundant signal effect; inhibitory control; behavioral impairment
8.  Inhibitory Functioning across ADHD Subtypes: Recent Findings, Clinical Implications and Future Directions 
Although growing consensus supports the role of deficient behavioral inhibition as a central feature of the combined subtype of ADHD (ADHD/C; Barkley, 2007; Nigg, 2001), little research has focused on how this finding generalizes to the primarily inattentive subtype (ADHD/I). This question holds particular relevance in light of recent work suggesting that ADHD/I might be better characterized as a disorder separate from ADHD/C (Diamond, 2005; Milich et al., 2001). The current paper describes major findings in the area of inhibitory performance in ADHD and highlights recent research suggesting important areas of divergence between the subtypes. In particular, preliminary findings point to potential differences between the subtypes with respect to how children process important contextual information from the environment, such as preparatory cues that precede responses and rewarding or punishing feedback following behavior. These suggestive findings are discussed in the context of treatment implications, which could involve differential intervention approaches for each subtype targeted to the specific deficit profiles that characterize each group of children. Future research avenues aimed toward building a sound theoretical model of ADHD/I and a better understanding of its relation to ADHD/C are also presented. Specifically, investigators are encouraged to continue studying the complex interplay between inhibitory and attentional processes, as this area seems particularly promising in its ability to improve our understanding of the potentially distinct pathologies underlying the ADHD subtypes.
PMCID: PMC4131681  PMID: 19072751
ADHD; subtypes; inhibition; contextual factors
9.  Examining Manual and Visual Response Inhibition among ADHD Subtypes 
This study compared inhibitory functioning among ADHD subtype groups on manual and visual versions of the stop task. Seventy-six children, identified as ADHD/I (n = 17), ADHD/C (n =43), and comparison (n = 20) completed both tasks. Results indicated that both ADHD groups were slower to inhibit responses than the comparison group on both tasks. Comparison children were faster to inhibit than activate responses on both tasks. Children in the ADHD groups also demonstrated this robust pattern on the manual task. However, on the visual task, the ADHD groups evidenced slowed inhibition comparable to the time required to activate responding. This implies that the visual task is more sensitive than the manual task to inhibitory deficits associated with ADHD. The ADHD/I and the ADHD/C groups did not differ on most measures, suggesting that neither stop task is effective in differentiating the subtypes. These findings extend work highlighting the role of disinhibition in ADHD, and contrast recent work suggesting divergence between ADHD subtypes.
PMCID: PMC4100534  PMID: 20449644
ADHD; subtypes; inhibition; oculomotor
10.  Reduced Acute Recovery from Alcohol Impairment in Adults with ADHD 
Psychopharmacology  2013;228(1):65-74.
Prior research has found that adults with attention-deficit/hyperactivity disorder (ADHD) show increased sensitivity to the impairing effects of alcohol (Weafer et al. 2009). However, these studies have focused exclusively on the ascending limb of the blood alcohol concentration (BAC) curve, and it is unclear whether these adults continue to show increased sensitivity during the later phase of the dose as BAC is declining.
This study tested the hypothesis that those with ADHD would display increased response to alcohol during the ascending limb of the BAC curve and less recovery from the impairing effects during the descending limb.
Adult social drinkers with ADHD and control adults completed measures of motor coordination, reaction time, and subjective intoxication twice following 0.64 g/kg alcohol and placebo. The measures were administered during the ascending limb of the BAC curve and again during the descending limb.
During the ascending limb, alcohol reduced motor coordination, slowed reaction time (RT), and increased self-reports of subjective intoxication. Those with ADHD displayed greater impairment of motor coordination compared with controls. During the descending limb, controls reported diminished subjective intoxication and showed recovery from the impairing effects of alcohol on both their motor coordination and their RT. Those with ADHD showed reduced subjective intoxication and faster RT during this time, but they did not recover motor control.
The protracted time course of motor impairment in adults with ADHD despite reductions in subjective intoxication may contribute to poor decision making and diminished behavioral control in this group.
PMCID: PMC3679354  PMID: 23430161
acute recovery; alcohol impairment; motor control; response time; ADHD; at-risk drinkers
12.  Acute Alcohol Effects on Attentional Bias in Heavy and Moderate Drinkers 
Heavy drinkers show an increased attentional bias to alcohol-related stimuli compared to moderate drinkers, and this bias is thought to promote motivation for alcohol consumption (Field & Cox, 2008). Studies have begun to examine acute alcohol effects on attentional bias, however little is known regarding how these effects might differ based on drinker type. Further, the degree to which attentional bias in response to alcohol is associated with excessive alcohol consumption remains unexplored. For the current study, 20 heavy drinkers and 20 moderate drinkers completed a visual probe task in response to placebo and two active doses of alcohol (0.45 g/kg and 0.65 g/kg). Participants’ eye-movements were monitored and attentional bias was calculated as the difference in time spent focused on alcohol compared to neutral images. Participants’ alcohol consumption was assessed by a timeline follow-back calendar and a laboratory ad lib consumption task. Results showed that heavy drinkers displayed significantly greater attentional bias than did moderate drinkers following placebo. However, heavy drinkers displayed a dose-dependent decrease in attentional bias following alcohol, whereas the drug had no effect in moderate drinkers. Individual differences in attentional bias under placebo were strongly associated with both self-reported and laboratory alcohol consumption, yet bias following alcohol administration did not predict either measure of consumption. These findings suggest that attentional bias is strongest before a drinking episode begins. As such, an attentional bias might be most influential in terms of initiation of alcohol consumption, and less of a factor in promoting continued consumption within the drinking episode.
PMCID: PMC3460038  PMID: 22732051
attentional bias; alcohol; heavy drinkers
13.  Mixing an Energy Drink with an Alcoholic Beverage Increases Motivation for More Alcohol in College Students 
There has been a dramatic rise in the consumption of alcohol mixed with energy drinks (AmED) in social drinkers. It has been suggested that AmED beverages might lead individuals to drink greater quantities of alcohol. This experiment was designed to investigate if the consumption of AmED would alter alcohol priming (i.e., increasing ratings of wanting another drink) compared with alcohol alone.
Participants (n = 80) of equal gender attended one session where they were randomly assigned to receive one of 4 doses (0.91 ml/kg vodka, 1.82 ml/kg energy drink, 0.91 ml/kg vodka mixed with 1.82 ml/kg energy drink (AmED), or a placebo beverage). Alcohol-induced priming of the motivation to drink was assessed by self-reported ratings on the Desire-for-Drug questionnaire.
The priming dose of alcohol increased the subjective ratings of “desire” for more alcohol, consistent with previous research that small doses of alcohol can increase the motivation to drink. Furthermore, higher desire ratings over time were observed with AmED compared to alcohol alone. Finally, ratings of liking the drink were similar for the alcohol and AmED conditions.
An energy drink may elicit increased alcohol priming. This study provides laboratory evidence that AmED beverages may lead to greater motivation to drink versus the same amount of alcohol consumed alone.
PMCID: PMC3459310  PMID: 22724427
Alcohol; Energy Drink; Priming; Motivation to Drink; College Students
14.  Acute Tolerance to Alcohol in At-risk Binge Drinkers 
Studies of the impairing effects of alcohol on behavior often show greater tolerance in heavy drinkers compared to light drinkers, suggesting a causal link between heavy consumption and tolerance. Tolerance also develops during the time-course of a single drinking episode, and this “acute tolerance” might play an important role in the escalation to heavy drinking. The present study examined the development of acute tolerance to the impairing effects of alcohol on motor coordination and inhibitory control in a group of at-risk, binge drinkers (N = 20) and a group of non-risk, moderate drinkers (N = 20). Participants performed the testing battery in response to placebo and a moderate dose of alcohol (0.65 g/kg) twice at comparable blood alcohol concentrations (BACs): once on the ascending limb and once on the descending limb of the blood alcohol curve. Results showed marked acute tolerance to the impairing effects of alcohol on motor coordination in the at-risk drinkers. By contrast, no recovery of motor skill was observed in the non-risk drinkers. Regarding inhibitory control, both groups remained impaired on both the ascending and descending limbs, indicating no acute tolerance in either group. The findings suggest that at-risk, binge drinkers display a faster recovery in their ability to execute versus inhibit action under alcohol. Such an “activational bias” of behavior could account for their continued alcohol consumption and impulsive behaviors while intoxicated, especially as BAC begins to decline.
PMCID: PMC3326440  PMID: 22023021
Alcohol; acute tolerance; binge; inhibitory control; motor coordination
15.  Lack of tolerance to the disinhibiting effects of alcohol in heavy drinkers 
Psychopharmacology  2012;224(4):511-518.
Alcohol tolerance is observed as a diminished response to a given dose as a function of repeated administrations of the drug. Research has consistently shown that heavier drinkers display reduced reactions to alcohol (i.e., tolerance) compared with lighter drinkers. However, the majority of this work has focused primarily on measures of motor performance, whereas the development of tolerance to alcohol’s impairing effects on cognitive processes, such as inhibitory mechanisms of behavioral control, remains relatively unexplored.
The purpose of the present study was to examine the relationship between drinking habits and the degree to which alcohol affects drinkers’ inhibitory control and motor coordination.
Fifty-two non-dependent drinkers reported their recent drinking patterns. Their inhibitory control and motor coordination were measured in response to placebo and 0.65 g/kg alcohol.
Alcohol significantly impaired inhibitory control and motor coordination compared with placebo. Moreover, greater quantity and frequency of recent consumption predicted less alcohol impairment of motor coordination. However, there was no relationship between recent drinking habits and the degree of impairment of inhibitory control.
These findings suggest that tolerance to the disinhibiting effects of alcohol might not readily develop as a result of recent, heavy drinking.
PMCID: PMC3593342  PMID: 22763668
Alcohol; Tolerance; Inhibitory control; Motor coordination
16.  Comparison of Alcohol Impairment of Behavioral and Attentional Inhibition 
Drug and alcohol dependence  2012;126(1-2):176-182.
Despite the wealth of studies demonstrating the impairing effects of alcohol on behavioral inhibition, less is known regarding effects of the drug on attentional inhibition (i.e., the ability to ignore distracting stimuli in the environment in order to focus attention on relevant information). The current study examined alcohol impairment of both behavioral and attentional inhibition, as well as potential associations between the two mechanisms of inhibitory control.
Men (n = 27) and women (n = 21) performed a measure of behavioral inhibition (cued go/no-go task) and a measure of attentional inhibition (delayed ocular return task) following three doses of alcohol: 0.65 g/kg, 0.45 g/kg, and 0.0 g/kg (placebo).
Alcohol impaired both behavioral and attentional inhibition relative to placebo; however, correlational analyses revealed no associations between measures of behavioral and attentional inhibition following any dose. Additionally, men committed more inhibitory failures on the behavioral inhibition task, whereas women committed more inhibitory failures on the attentional inhibition task.
These findings suggest that behavioral and attentional inhibition are equally sensitive to the impairing effects of alcohol, yet represent distinct components of inhibitory control. Additionally, the observed gender differences in control of behavior and attention could have important implications regarding negative consequences associated with alcohol-induced disinhibition in men and women.
PMCID: PMC3440541  PMID: 22673197
alcohol; behavioral inhibition; attentional inhibition; gender
17.  Effects of energy drinks mixed with alcohol on information processing, motor coordination and subjective reports of intoxication 
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.
PMCID: PMC3288788  PMID: 22023670
alcohol; energy drink; dual-task interference; mental fatigue; stimulation
18.  Drinking to Distraction: Does Alcohol Increase Attentional Bias in Adults with ADHD? 
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.
PMCID: PMC3338153  PMID: 22121850
Attentional bias; ADHD; Alcohol; Ad libitum consumption; At-risk drinkers
19.  Linking Impulsivity and Inhibitory Control Using Manual and Oculomotor Response Inhibition Tasks 
Acta psychologica  2011;138(3):419-428.
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.
PMCID: PMC3205291  PMID: 21982865
impulsivity; inhibitory control; manual; oculomotor; ADHD
20.  Defining “Binge” Drinking as Five Drinks per Occasion or Drinking to a 0.08% BAC: Which is More Sensitive to Risk? 
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.
PMCID: PMC3156624  PMID: 21838847
Drug and alcohol dependence  2011;117(1):31-37.
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.
PMCID: PMC3101290  PMID: 21277119
Alcohol; Distraction; Divided Attention; Driving
22.  Effects of energy drinks mixed with alcohol on behavioral control: Risks for college students consuming trendy cocktails 
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.
PMCID: PMC3117195  PMID: 21676002
alcohol; energy drink; behavioral control; reaction time; stimulation
23.  Does Response Variability Predict Distractibility among Adults with Attention-Deficit/Hyperactivity Disorder? 
Psychological assessment  2011;23(2):427-436.
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.
PMCID: PMC3115498  PMID: 21443365
ADHD; adults; variable attention; eye movements
24.  Separating Automatic and Intentional Inhibitory Mechanisms of Attention in Adults with Attention-Deficit/Hyperactivity Disorder 
Journal of abnormal psychology  2011;120(1):223-233.
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.
PMCID: PMC3065892  PMID: 21058752
ADHD; inhibition; automatic; intentional
25.  Behavioral Components of Impulsivity Predict Alcohol Consumption in Adults with ADHD and Healthy Controls 
Drug and alcohol dependence  2010;113(2-3):139-146.
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.
PMCID: PMC3010339  PMID: 20863628
behavioral impulsivity; alcohol consumption; ADHD

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