Jessica Weafer

Individual differences in acute alcohol impairment of inhibitory control predict ad libitum alcohol consumption.

RationaleResearch 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.ObjectiveThe 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 methodsTwenty-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 (0.65xa0g/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.ResultsIn accord with the hypothesis, greater impairment of inhibitory control from alcohol was associated with increased ad lib consumption.ConclusionAcute impairment of inhibitory control might be an important cognitive effect that contributes to abuse in addition to the positive rewarding effects of the drug.

Simulated driving performance of adults with ADHD: comparisons with alcohol intoxication

Previous research has demonstrated that adults with attention deficit/hyperactivity disorder (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 2 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 blood alcohol concentration 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 3 doses of alcohol: 0.65g/kg, 0.45g/kg, and 0.0g/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.

Test-retest reliability of behavioral measures of impulsive choice, impulsive action, and inattention

Behavioral measures of impulsivity are widely used in substance abuse research, yet relatively little attention has been devoted to establishing their psychometric properties, especially their reliability over repeated administration. The current study examined the test-retest reliability of a battery of standardized behavioral impulsivity tasks, including measures of impulsive choice (i.e., delay discounting, probability discounting, and the Balloon Analogue Risk Task), impulsive action (i.e., the stop signal task, the go/no-go task, and commission errors on the continuous performance task), and inattention (i.e., attention lapses on a simple reaction time task and omission errors on the continuous performance task). Healthy adults (n = 128) performed the battery on two separate occasions. Reliability estimates for the individual tasks ranged from moderate to high, with Pearson correlations within the specific impulsivity domains as follows: impulsive choice (r range: .76-.89, ps < .001); impulsive action (r range: .65-.73, ps < .001); and inattention (r range: .38-.42, ps < .001). Additionally, the influence of day-to-day fluctuations in mood, as measured by the Profile of Mood States, was assessed in relation to variability in performance on each of the behavioral tasks. Change in performance on the delay discounting task was significantly associated with change in positive mood and arousal. No other behavioral measures were significantly associated with mood. In sum, the current analysis demonstrates that behavioral measures of impulsivity are reliable measures and thus can be confidently used to assess various facets of impulsivity as intermediate phenotypes for drug abuse.

Behavioral components of impulsivity predict alcohol consumption in adults with ADHD and healthy controls.

BACKGROUNDnThe 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.nnnMETHODSnThe 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).nnnRESULTSnBoth 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.nnnCONCLUSIONSnThese 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.

Sex differences in impulsive action and impulsive choice

Here, we review the evidence for sex differences in behavioral measures of impulsivity for both humans and laboratory animals. We focus on two specific components of impulsivity: impulsive action (i.e., difficulty inhibiting a prepotent response) and impulsive choice (i.e., difficulty delaying gratification). Sex differences appear to exist on these measures, but the direction and magnitude of the differences vary. In laboratory animals, impulsive action is typically greater in males than females, whereas impulsive choice is typically greater in females. In humans, women discount more steeply than men, but sex differences on measures of impulsive action depend on tasks and subject samples. We discuss implications of these findings as they relate to drug addiction. We also point out the major gaps in this research to date, including the lack of studies designed specifically to examine sex differences in behavioral impulsivity, and the lack of consideration of menstrual or estrous phase or sex hormone levels in the studies.

Gender Differences in Alcohol Impairment of Simulated Driving Performance and Driving-Related Skills

AIMSnConsiderable 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.nnnMETHODSnDrawing 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.nnnRESULTSnAlcohol 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.nnnCONCLUSIONSnBoth 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.

Alcohol-related stimuli reduce inhibitory control of behavior in drinkers

RationalePoor 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.ObjectivesThe 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.MethodsFifty 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.ResultsAs 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.ConclusionsThese 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.

Acute tolerance to alcohol impairment of behavioral and cognitive mechanisms related to driving: drinking and driving on the descending limb

RationaleAlcohol 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.ObjectivesTo 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.MethodsSocial-drinking adults (Nu2009=u200920) 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 (0.65xa0g/kg) twice at comparable blood alcohol concentrations: once on the ascending limb and again on the descending limb.ResultsImpaired 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.ConclusionsFindings 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.

Increased Sensitivity to the Disinhibiting Effects of Alcohol in Adults with ADHD

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 attention-deficit/hyperactivity disorder (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 has shown 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.

The latent structure of impulsivity: impulsive choice, impulsive action, and impulsive personality traits

RationaleImpulsivity has been strongly linked to addictive behaviors, but can be operationalized in a number of ways that vary considerably in overlap, suggesting multidimensionality.ObjectiveThis study tested the hypothesis that the latent structure among multiple measures of impulsivity would reflect the following three broad categories: impulsive choice, reflecting discounting of delayed rewards; impulsive action, reflecting ability to inhibit a prepotent motor response; and impulsive personality traits, reflecting self-reported attributions of self-regulatory capacity.MethodsThe study used a cross-sectional confirmatory factor analysis of multiple impulsivity assessments. Participants were 1252 young adults (62xa0% female) with low levels of addictive behavior, who were assessed in individual laboratory rooms at the University of Chicago and the University of Georgia. The battery comprised a Delayxa0(replace hyphen with space) Discounting Task, Monetary Choice Questionnaire, Conners’ Continuous Performance Test, Go/NoGo Task, Stop Signal Task, Barratt Impulsiveness Scale, and the UPPS-P Impulsive Behavior Scale.ResultsThe hypothesized three-factor model provided the best fit to the data, although sensation seeking was excluded from the final model. The three latent factors were largely unrelated to each other and were variably associated with substance use.ConclusionsThese findings support the hypothesis that diverse measures of impulsivity can broadly be organized into three categories that are largely distinct from one another. These findings warrant investigation among individuals with clinical levels of addictive behavior and may be applied to understanding the underlying biological mechanisms of these categories.