Cannabis involvement and neuropsychological performance: findings from the Human Connectome Project

Background: There is evidence that heavy cannabis use is associated with decrements in cognitive performance, but findings are mixed and studies are often limited by small sample sizes and narrow adjustment for potential confounding variables. In a comparatively large sample, the current study examined associations between multiple indicators of cannabis use in relation to performance on a variety of neuropsychological tasks. Methods: Participants were 1121 adults (54% female) enrolled in the Human Connectome Project. Cannabis involvement comprised recent cannabis use (positive tetrahydrocannabinol screen), total number of lifetime uses, cannabis use disorder and age at first use. The neuropsychological battery comprised performance in episodic memory, fluid intelligence, attention, working memory, executive function, impulsive decision-making, processing speed and psychomotor dexterity. Covariates were age, sex, income, family structure and alcohol and tobacco use. Results: Positive urinary tetrahydrocannabinol status was associated with worse performance in episodic memory and processing speed, and positive cannabis use disorder status was associated with lower fluid intelligence (all p < 0.005). No other significant associations were present. Limitations: The sample was limited to young adults aged 22­36 years. The measures of cannabis involvement were relatively coarse. Conclusion: Beyond an array of potential confounders, recent cannabis use was associated with deficits in memory and psychomotor performance, and cannabis use disorder was associated with lower overall cognitive functioning in a large normative sample of adults. The findings pertaining to recent use have particular relevance for occupational settings.

Neuroanatomical foundations of delayed reward discounting decision making.

Resolving tradeoffs between smaller immediate rewards and larger delayed rewards is ubiquitous in daily life and steep discounting of future rewards is associated with several psychiatric conditions. This form of decision-making is referred to as delayed reward discounting (DRD) and the features of brain structure associated with DRD are not well understood. The current study characterized the relationship between gray matter volume (GMV) and DRD in a sample of 1038 healthy adults (54.7% female) using cortical parcellation, subcortical segmentation, and voxelwise cortical surface-based group analyses. The results indicate that steeper DRD was significantly associated with lower total cortical GMV, but not subcortical GMV. In parcellation analyses, less GMV in 20 discrete cortical regions was associated with steeper DRD. Of these regions, only GMV in the middle temporal gyrus (MTG) and entorhinal cortex (EC) were uniquely associated with DRD. Voxelwise surface-based analyses corroborated these findings, again revealing significant associations between steeper DRD and less GMV in the MTG and EC. To inform the roles of MTG and EC in DRD, connectivity analysis of resting state data (N = 1003) using seed regions from the structural findings was conducted. This revealed that spontaneous activity in the MTG and EC was correlated with activation in the ventromedial prefrontal cortex, posterior cingulate cortex, and inferior parietal lobule, regions associated with the default mode network, which involves prospection, self-reflective thinking and mental simulation. Furthermore, meta-analytic co-activation analysis using Neurosynth revealed a similar pattern across 11,406 task-fMRI studies. Collectively, these findings provide robust evidence that morphometric characteristics of the temporal lobe are associated with DRD preferences and suggest it may be because of their role in mental activities in common with default mode activity.

Association between overall rate of change in rising breath alcohol concentration and the magnitude of acute tolerance of subjective intoxication via the Mellanby method.

OBJECTIVE: The magnitude of acute tolerance is a strong predictor of the development of longer-term chronic tolerance and plays a decisive role in risky decisions (e.g., driving after drinking). Therefore, it is important to identify factors that increase the magnitude of this adaptive process. This study explored whether acute tolerance magnitude varied as a function of the overall rate of increase in breath alcohol concentration (BrAC). METHODS: Twenty-nine young adult social drinkers (M age = 22.55, SD = 3.10; 62.1% women) consumed a moderate dose of alcohol (men: 0.86 g/kg, women: 0.75 g/kg) in a controlled laboratory setting. Subjective intoxication was assessed at matched BrACs (~0.060 g/dl) on each limb of the BrAC curve. RESULTS: Hierarchical regression results indicated that faster overall increases in BrAC on the ascending limb were associated with greater acute tolerance for subjective intoxication ratings (p < .01, R2  = .29). CONCLUSIONS: These results present some of the first evidence that faster increases in BrAC may be associated with greater acute tolerance, as indicated by greater reduction in subjective intoxication across the limbs of the BrAC curve. This greater reduction may, in turn, promote heavier drinking and/or engagement in behaviors for which one is unfit (e.g., driving after drinking).

Left-digit price effects on smoking cessation motivation.

BACKGROUND: Cigarette price increases have been associated with increases in smoking cessation, but relatively little is known about this relationship at the level of individual smokers. To address this and to inform tax policy, the goal of this study was to apply a behavioural economic approach to the relationship between the price of cigarettes and the probability of attempting smoking cessation. METHODS: Adult daily smokers (n=1074; ie, 5+ cigarettes/day; 18+ years old; ≥8th grade education) completed in-person descriptive survey assessments. Assessments included estimated probability of making a smoking cessation attempt across a range of cigarette prices, demographics and nicotine dependence. RESULTS: As price increases, probability of making a smoking cessation attempt exhibited an orderly increase, with the form of the relationship being similar to an inverted demand curve. The largest effect size increases in motivation to make a quit attempt were in the form of 'left-digit effects,' (ie, maximal sensitivity across pack price whole-number changes; eg, US$5.80-6/pack). Significant differences were also observed among the left-digit effects, suggesting the most substantial effects were for price changes that were most market relevant. Severity of nicotine dependence was significantly associated with price sensitivity, but not for all indices. CONCLUSIONS: These data reveal the clear and robust relationship between the price of cigarettes and an individual's motivation to attempt smoking cessation. Furthermore, the current study indicates the importance of left-digit price transitions in this relationship, suggesting policymakers should consider relative price positions in the context of tax changes.

Longitudinal examination of alcohol demand and alcohol-related reinforcement as predictors of heavy drinking and adverse alcohol consequences in emerging adults.

BACKGROUND AND AIMS: Behavioral economic theory predicts that high alcohol demand and high proportionate alcohol-related reinforcement are important determinants of risky alcohol use in emerging adults, but the majority of research to date has been cross-sectional in nature. The present study investigated prospective and dynamic relationships between alcohol demand and proportionate alcohol-related reinforcement in relation to heavy drinking days and alcohol problems. DESIGN: Longitudinal cohort with assessments every 4 months for 20 months. SETTING: Ontario, Canada. PARTICIPANTS: Emerging adults reporting regular heavy episodic drinking (n = 636, Mage = 21.44; 55.8% female). MEASUREMENTS: Heavy drinking days (HDD; Daily Drinking Questionnaire), alcohol problems (Brief Young Adult Alcohol Consequences Questionnaire), alcohol demand (Alcohol Purchase Task) and proportionate alcohol-related reinforcement (Activity Level Questionnaire). FINDINGS: Linear mixed effects models revealed that behavioral economic indicators and alcohol-related outcomes significantly decreased over the study, consistent with 'aging out' of risky alcohol use. Random intercept cross-lagged panel models revealed significant between-person relationships, such that higher alcohol demand and alcohol-related reinforcement were positively associated with HDD and alcohol problems (random intercepts = 0.187-0.534, Ps < 0.01). Moreover, alcohol demand indicators (particularly the rate of change in elasticity of the demand curve, as measured by α, and the maximum expenditure, Omax) and proportionate alcohol-related reinforcement significantly forecasted changes in HDD at all time points (|ßs| = 0.063-0.103, Ps < 0.05) in cross-lagged relationships, with bidirectional associations noted for the rate of change in elasticity (ßs = -0.085 to -0.104, Ps < 0.01). Proportionate alcohol-related reinforcement also significantly forecasted changes in alcohol problems at all time points (ßs = 0.072-0.112, Ps < 0.01). CONCLUSIONS: Multiple behavioral economic indicators (demand elasticity, maximum expenditure and reinforcement ratio) forecast changes in heavy episodic drinking and alcohol problems over the course of emerging adulthood. These results further implicate alcohol demand and proportionate alcohol-related reinforcement as etiologically and developmentally important mechanisms in alcohol use trajectories.

Is talk "cheap"? An initial investigation of the equivalence of alcohol purchase task performance for hypothetical and actual rewards.

BACKGROUND: Behavioral economic alcohol purchase tasks (APTs) are self-report measures of alcohol demand that assess estimated consumption at escalating levels of price. However, the relationship between estimated performance for hypothetical outcomes and choices for actual outcomes has not been determined. The present study examined both the correspondence between choices for hypothetical and actual outcomes, and the correspondence between estimated alcohol consumption and actual drinking behavior. A collateral goal of the study was to examine the effects of alcohol cues on APT performance. METHODS: Forty-one heavy-drinking adults (56% men) participated in a human laboratory protocol comprising APTs for hypothetical and actual alcohol and money, an alcohol cue reactivity paradigm, an alcohol self-administration period, and a recovery period. RESULTS: Pearson correlations revealed very high correspondence between APT performance for hypothetical and actual alcohol (ps < 0.001). Estimated consumption on the APT was similarly strongly associated with actual consumption during the self-administration period (r = 0.87, p < 0.001). Exposure to alcohol cues significantly increased subjective craving and arousal and had a trend-level effect on intensity of demand, in spite of notable ceiling effects. Associations among motivational indices were highly variable, suggesting multidimensionality. CONCLUSIONS: These results suggest there may be close correspondence both between value preferences for hypothetical alcohol and actual alcohol, and between estimated consumption and actual consumption. Methodological considerations and priorities for future studies are discussed.

The neuroeconomics of nicotine dependence: a preliminary functional magnetic resonance imaging study of delay discounting of monetary and cigarette rewards in smokers.

Neuroeconomics integrates behavioral economics and cognitive neuroscience to understand the neurobiological basis for normative and maladaptive decision making. Delay discounting is a behavioral economic index of impulsivity that reflects capacity to delay gratification and has been consistently associated with nicotine dependence. This preliminary study used functional magnetic resonance imaging to examine delay discounting for money and cigarette rewards in 13 nicotine dependent adults. Significant differences between preferences for smaller immediate rewards and larger delayed rewards were evident in a number of regions of interest (ROIs), including the medial prefrontal cortex, anterior insular cortex, middle temporal gyrus, middle frontal gyrus, and cingulate gyrus. Significant differences between money and cigarette rewards were generally lateralized, with cigarette choices associated with left hemisphere activation and money choices associated with right hemisphere activation. Specific ROI differences included the posterior parietal cortex, medial and middle frontal gyrus, ventral striatum, temporoparietal cortex, and angular gyrus. Impulsivity as measured by behavioral choices was significantly associated with both individual ROIs and a combined ROI model. These findings provide initial evidence in support of applying a neuroeconomic approach to understanding nicotine dependence.

Urinary tetrahydrocannabinol is associated with poorer working memory performance and alterations in associated brain activity.

Worldwide, cannabis is one of the most widely used psychoactive substances and cannabis use has been implicated in poorer performance in several cognitive domains, including working memory (WM). However, the neural mechanisms underlying these WM decrements are not well understood and the current study investigated the association of cannabis involvement with WM performance and associated neural activation in the Human Connectome Project (N = 1038). Multiple indicators of cannabis involvement were examined in relation to behavioral performance and brain activity in a visual N-back task using functional magnetic resonance imaging. A positive urine drug screen for tetrahydocannabinol (THC+ status), the principal psychoactive constituent in cannabis, was associated with worse WM performance and differential brain response in areas previously linked to WM performance. Furthermore, decreases in blood-activation-level-dependent (BOLD) signal in WM task-positive brain regions and increases in task-negative regions mediated the relationship between THC+ status and WM performance. In contrast, WM performance and BOLD response during the N-back task were not associated with total lifetime cannabis use, age of first use, or other indicators of involvement, suggesting that the effects of cannabis on WM were short-term residual effects, rather than long-term persistent effects. These findings elucidate differential influences of cannabis involvement on neurocognition and have significant potential implications for occupational performance in diverse settings.

Negative urgency moderates reactivity to laboratory stress inductions.

Impulsive personality traits refer to a group of self-reported dispositions about self-regulatory capacity, several of which have been linked to diverse forms of psychopathology. One of these is negative urgency (NUR), the propensity to act out when experiencing negative emotions, which has been linked to substance use disorders and eating disorders. However, few laboratory studies have investigated the extent to which self-reported NUR relates to an individual's in vivo emotional and behavioral responses. Harmonizing two archival data sets on alcohol and high-energy-dense (HED) food motivation, the current study investigated NUR as a moderator of reactivity to stressful situations elicited by two commonly used stress manipulations, the Trier Social Stress Test and a stress imagery induction. A sample of 148 adults was assessed for NUR, severity of alcohol misuse or binge eating, and measures of negative affect and psychophysiological arousal (i.e., heart rate and blood pressure) prior to and following one of the two manipulations. In addition, a behavioral multiple-choice procedure assessing the relative reinforcing value of alcohol or HED foods followed the manipulations. As predicted, NUR positively moderated the effects of stress induction on self-reported negative affect and relative reinforcing value, although not arousal. Individuals exhibiting elevated NUR also exhibited greater alcohol misuse, although not greater binge eating severity. These findings provide in vivo validation of the construct of NUR and its measurement using the UPPS-P Impulsive Behavior Scale. More broadly, these findings inform the understanding of deficits that are characteristic of self-regulatory disorders. (PsycINFO Database Record

Delay discounting differences in brain activation, connectivity, and structure in individuals with addiction: a systematic review protocol.

BACKGROUND: Delayed reward discounting (DRD), the degree to which future rewards are discounted relative to immediate rewards, is used as an index of impulsive decision-making and has been associated with a number of problematic health behaviors. Given the robust behavioral association between DRD and addictive behavior, there is an expanding literature investigating the differences in the functional and structural correlates of DRD in the brain between addicted and healthy individuals. However, there has yet to be a systematic review which characterizes differences in regional brain activation, functional connectivity, and structure and places them in the larger context of the DRD literature. The objective of this systematic review is to summarize and critically appraise the existing literature examining differences between addicted and healthy individuals in the neural correlates of DRD using magnetic resonance imaging (MRI) or functional magnetic resonance imaging (fMRI). METHODS: A systematic search strategy will be implemented that uses Boolean search terms in PubMed/MEDLINE and PsycINFO, as well as manual search methods, to identify the studies comprehensively. This review will include studies using MRI or fMRI in humans to directly compare brain activation, functional connectivity, or structure in relation to DRD between addicted and healthy individuals or continuously assess addiction severity in the context of DRD. Two independent reviewers will determine studies that meet the inclusion criteria for this review, extract data from included studies, and assess the quality of included studies using the Grading of Recommendations Assessment, Development and Evaluation framework. Then, narrative review will be used to explicate the differences in structural and functional correlates of DRD implicated by the literature and assess the strength of evidence for this conclusion. DISCUSSION: This review will provide a needed critical exegesis of the MRI studies that have been conducted investigating brain differences in addictive behavior in relation to healthy samples in the context of DRD. This will provide clarity on the elements of neural activation, connectivity, and structure that are most implicated in the differences in DRD seen in addicted individuals. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42017056857.

The Neuroeconomics of Tobacco Demand: An Initial Investigation of the Neural Correlates of Cigarette Cost-Benefit Decision Making in Male Smokers.

How the brain processes cigarette cost-benefit decision making remains largely unknown. Using functional magnetic resonance imaging (fMRI), this study investigated the neural correlates of decisions for cigarettes (0-10 cigarettes) at varying levels of price during a Cigarette Purchase Task (CPT) in male regular smokers (N = 35). Differential neural activity was examined between choices classified as inelastic, elastic, and suppressed demand, operationalized as consumption unaffected by cost, partially suppressed by cost, and entirely suppressed by cost, respectively. Decisions reflecting elastic demand, putatively the most effortful decisions, elicited greater activation in regions associated with inhibition and planning (e.g., middle frontal gyrus and inferior frontal gyrus), craving and interoceptive processing (anterior insula), and conflict monitoring (e.g., anterior cingulate cortex). Exploratory examination in a harmonized dataset of both cigarette and alcohol demand (N = 59) suggested common neural activation patterns across commodities, particularly in the anterior insula, caudate, anterior cingulate, medial frontal gyrus, and dorsolateral prefrontal cortex. Collectively, these findings provide initial validation of a CPT fMRI paradigm; reveal the interplay of brain regions associated with executive functioning, incentive salience, and interoceptive processing in cigarette decision making; and add to the literature implicating the insula as a key brain region in addiction.

Syntax for calculation of discounting indices from the monetary choice questionnaire and probability discounting questionnaire.

The 27-item Monetary Choice Questionnaire (MCQ; Kirby, Petry, & Bickel, 1999) and 30-item Probability Discounting Questionnaire (PDQ; Madden, Petry, & Johnson, 2009) are widely used, validated measures of preferences for immediate versus delayed rewards and guaranteed versus risky rewards, respectively. The MCQ measures delayed discounting by asking individuals to choose between rewards available immediately and larger rewards available after a delay. The PDQ measures probability discounting by asking individuals to choose between guaranteed rewards and a chance at winning larger rewards. Numerous studies have implicated these measures in addiction and other health behaviors. Unlike typical self-report measures, the MCQ and PDQ generate inferred hyperbolic temporal and probability discounting functions by comparing choice preferences to arrays of functions to which the individual items are preconfigured. This article provides R and SPSS syntax for processing the MCQ and PDQ. Specifically, for the MCQ, the syntax generates k values, consistency of the inferred k, and immediate choice ratios; for the PDQ, the syntax generates h indices, consistency of the inferred h, and risky choice ratios. The syntax is intended to increase the accessibility of these measures, expedite the data processing, and reduce risk for error.

Separate and joint effects of alcohol and caffeine on conflict monitoring and adaptation.

RATIONALE: Caffeine is commonly believed to offset the acute effects of alcohol, but some evidence suggests that cognitive processes remain impaired when caffeine and alcohol are coadministered. OBJECTIVES: No previous study has investigated the separate and joint effects of alcohol and caffeine on conflict monitoring and adaptation, processes thought to be critical for self-regulation. This was the purpose of the current study. METHODS: Healthy, young adult social drinkers recruited from the community completed a flanker task after consuming one of four beverages in a 2 × 2 experimental design: Alcohol + caffeine, alcohol + placebo caffeine, placebo alcohol + caffeine, or placebo alcohol + placebo caffeine. Accuracy, response time, and the amplitude of the N2 component of the event-related potential (ERP), a neural index of conflict monitoring, were examined as a function of whether or not conflict was present (i.e., whether or not flankers were compatible with the target) on both the previous trial and the current trial. RESULTS: Alcohol did not abolish conflict monitoring or adaptation. Caffeine eliminated conflict adaptation in sequential trials but also enhanced neural conflict monitoring. The combined effect of alcohol and caffeine was apparent only in how previous conflict affected the neural conflict monitoring response. CONCLUSIONS: Together, the findings suggest that caffeine leads to exaggeration of attentional resource utilization, which could provide short-term benefits but lead to problems conserving resources for when they are most needed.

Effects of acute alcohol tolerance on perceptions of danger and willingness to drive after drinking.

RATIONALE: Drinking and driving is associated with elevated rates of motor vehicle accidents and fatalities. Previous research suggests that alcohol impairs judgments about the dangers of risky behaviors; however, how alcohol affects driving-related judgments is less clear. Impairments have also been shown to differ across limbs of the blood alcohol concentration (BAC) curve, which is known as acute tolerance. OBJECTIVES: The objectives of this study were to examine whether perceptions about the dangerousness of driving after drinking and willingness to drive differed across the ascending and descending limbs of the BAC curve and to test whether reductions in perceived danger were associated with willingness to drive on the descending limb. METHODS: Fifty-six participants were randomly assigned to receive either a moderate dose of alcohol (peak BAC = 0.10 g%) or placebo. We assessed perceived dangerousness and willingness to drive at matched BACs (~0.067-0.068 g%) on the ascending and descending limbs. RESULTS: Both perceived danger and willingness to drive showed acute tolerance in the alcohol group. Participants judged driving to be significantly less dangerous and were more willing to drive on the descending limb compared to the ascending limb. The magnitude of change in perceived danger significantly predicted willingness to drive on the descending limb. CONCLUSIONS: Decreased impairment associated with acute tolerance may lead individuals to underestimate the dangerousness of driving after drinking and in turn make poor decisions regarding driving. This study further emphasizes the descending limb as a period of increased risk and offers support for enhancing prevention efforts by targeting drivers at declining BAC levels.

Clarifying the neural basis for incentive salience of tobacco cues in smokers.

In functional magnetic resonance imaging (fMRI) studies, smoking cues have been found to elicit increases in brain activity in regions associated with processing rewarding and emotional stimuli. However, most smoking cue studies to date have reported effects relative to neutral control stimuli with no incentive properties, making it unclear whether the observed activation pertains to value in general or the value of cigarettes in particular. The current fMRI study sought to clarify the neural activity reflecting tobacco-specific incentive value versus domain-general incentive value by examining smoking cues, neutral cues, and a third set of cues, monetary cues, which served as an active control condition. Participants were 42 male daily smokers. Compared to neutral cues, significantly greater activation was found in the left ventral striatum in response to tobacco and money cues. Monetary cues also elicited significantly increased activation in the right inferior frontal gyrus and cuneus compared to the other two cue types. Overall, the results suggest that the salience of monetary cues was the highest and, as a result, might have reduced the incentive salience of tobacco cues.

Item-based analysis of delayed reward discounting decision making.

Delayed reward discounting (DRD) is a behavioral economic index of time preference, referring to how much an individual devalues a reward based on its delay in time, and has been linked to a wide array of health behaviors. It is commonly assessed using a task that asks participants to make dichotomous choices between two monetary rewards, one available immediately and the other after a delay. This study sought to shorten an extended iterative DRD assessment to increase its versatility and efficiency. Data were drawn from two young adult samples, an exploratory sample (N=130) and a confirmatory sample (N=247). In the exploratory sample, eight items were identified as predicting the majority of the variance in the full task area under the curve (AUC) (R(2)=.821; p<.001). In the confirmatory sample, the same eight items similarly predicted the majority of variance in the full task AUC (R(2)=.844, p<.001). These results provide initial support for the validity of a brief 8-item assessment of DRD. Priorities for further validation and potential applications are discussed.

The neuroeconomics of alcohol demand: an initial investigation of the neural correlates of alcohol cost-benefit decision making in heavy drinking men.

Neuroeconomics integrates concepts and methods from psychology, economics, and cognitive neuroscience to understand how the brain makes decisions. In economics, demand refers to the relationship between a commodity's consumption and its cost, and, in behavioral studies, high alcohol demand has been consistently associated with greater alcohol misuse. Relatively little is known about how the brain processes demand decision making, and the current study is an initial investigation of the neural correlates of alcohol demand among heavy drinkers. Using an event-related functional magnetic resonance imaging (fMRI) paradigm, participants (N=24) selected how much they would drink under varying levels of price. These choices determined access to alcohol during a subsequent bar laboratory self-administration period. During decisions to drink in general, greater activity was present in multiple distinct subunits of the prefrontal and parietal cortices. In contrast, during decisions to drink that were demonstrably affected by the cost of alcohol, significantly greater activation was evident in frontostriatal regions, suggesting an active interplay between cognitive deliberation and subjective reward value. These choices were also characterized by significant deactivation in default mode network regions, suggesting suppression resulting from greater cognitive load. Across choice types, the anterior insula was notably recruited in diverse roles, further implicating the importance of interoceptive processing in decision-making behavior. These findings reveal the neural signatures subserving alcohol cost-benefit decision making, providing a foundation for future clinical applications of this paradigm and extending this approach to understanding the neural correlates of demand for other addictive commodities.

Neural correlates of behavioral variation in healthy adults' antisaccade performance.

Cognitive control is required for correct antisaccade performance. High antisaccade error rates characterize certain psychiatric disorders, but can be highly variable, even among healthy groups. Antisaccade data were acquired from a large sample of healthy undergraduates, and error rate was quantified. Participants who reliably made few errors (good, n = 13) or many errors (poor, n = 13) were recruited back to perform antisaccades during fMRI acquisition. A data-derived model was used to compare signal between good and poor performers during blocks of antisaccade trials. Behaviorally derived regressors were used to compare signal between good and poor performers during correct and error trials. Results show differential activation in middle frontal gyrus and inferior parietal lobule between good and poor performers, suggesting that failure to recruit these top-down control regions corresponds to poor antisaccade performance in healthy young adults.

Initial development of a measure of expectancies for combinations of alcohol and caffeine: the Caffeine + Alcohol Combined Effects Questionnaire (CACEQ).

Caffeinated alcoholic beverage (CAB) consumption is widespread among young adults in the United States and is associated with increased negative consequences from alcohol. In addition to the direct pharmacological effects of adding caffeine to alcohol, another possible risk mechanism is via socially learned expectancies, which has received very little consideration. The current study conducted an initial psychometric validation of a measure of CAB expectancies to facilitate research in this area. Participants were 409 undergraduate regular drinkers (71% female) who were assessed for alcohol and CAB use, alcohol use/misuse, and expectancies about CABs. The majority (62%) of participants reported CAB experience and 48% reported CAB use in the past month. Participants primarily consumed spontaneously-prepared as opposed to premixed-CABs. More frequent CAB use was significantly positively correlated with levels of alcohol use and misuse. For the expectancy items, exploratory factor analysis revealed two factors that were labeled "Intoxication Enhancement" and "Avoid Negative Consequences." The patterns of expectancies reflected beliefs that CABs enhanced intoxication, but did not protect against negative consequences. The measure was titled the Caffeine + Alcohol Combined Effects Questionnaire (CACEQ). Intoxication enhancement scores were significantly associated with frequency of CAB use, even after adjusting for the role of weekly drinking and alcohol misuse, supporting the convergent validity of the CACEQ. These data provide initial support for the CACEQ and suggest it may be useful for clarifying the role of expectancies in CAB use. Applications for studying the risks associated with CAB use and methodological considerations are discussed.

Evidence from cluster analysis for differentiation of antisaccade performance groups based on speed/accuracy trade-offs.

Anti and pro-saccade performance in single or mixed contexts was explored in a large sample of young adults (n=281). ANOVAs were first conducted to evaluate trial type, context and gender effects. A cluster analysis was then used to determine whether subgroups could be identified based on saccadic performance variables. Increased antisaccade errors were observed among females and during mixed-saccade runs. Cluster analysis identified two groups: 1) increased errors clustered with faster latencies and 2) decreased errors clustered with slower latencies. These data offer justification for examining subgroups based on saccadic performance and may help elucidate mechanisms underlying response variability within and between different populations.