John Acker

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.

Behavioral economic analysis of cue-elicited craving for tobacco: a virtual reality study.

INTRODUCTION Subjective craving is a prominent construct in the study of tobacco motivation; yet, the precise measurement of tobacco craving poses several difficulties. A behavioral economic approach to understanding drug motivation imports concepts and methods from economics to improve the assessment of craving. METHODS Using an immersive virtual reality (VR) cue reactivity paradigm, this study tested the hypothesis that, compared with neutral cues, tobacco cues would result in significant increases in subjective craving and diverse aspects of demand for tobacco in a community sample of 47 regular smokers. In addition, the study examined these motivational indices in relation to a dual-component delay and cigarette consumption self-administration paradigm. RESULTS In response to the VR tobacco cues, significant increases were observed for tobacco craving and the demand indices of Omax (i.e., maximum total expenditure toward cigarettes) and Breakpoint (i.e., price at which consumption is completely suppressed), whereas a significant decrease was observed for Elasticity (i.e., lower cigarette price sensitivity). Continuous analyses revealed trend-level inverse associations between Omax and Intensity in relation to delay duration and significant positive associations between subjective craving, Omax, and Elasticity in relation to the number of cigarettes purchased. CONCLUSIONS The results from this study provide further evidence for the utility of behavioral economic concepts and methods in understanding smoking motivation. These data also reveal the incremental contribution of behavioral economic indices beyond subjective craving in predicting in vivo cigarette consumption. Relationships to previous studies and methodological considerations are discussed.

Temporal Stability of a Cigarette Purchase Task

INTRODUCTION Cigarette purchase tasks (CPTs) are relatively new behavioral economic assessments that efficiently quantify motivation for tobacco by assessing how much an individual values cigarettes. This is achieved by assessing estimated cigarette consumption at escalating levels of price per cigarette and generating several measures of motivation from the resulting demand curve. The temporal stability of the indices generated from a CPT has not been examined to date and was the focus of the current study. METHODS Participants were 11 moderately heavy smokers from the community who completed CPTs and other measures on 2 occasions 1 week apart. The CPT indices of the relative value of cigarettes were (a) intensity (i.e., consumption under minimal cost), (b) O(max) (i.e., maximum expenditure for cigarettes), (c) breakpoint (i.e., first price suppressing consumption to 0), and (d) elasticity (i.e., proportionate price sensitivity). RESULTS Demand for cigarettes was initially insensitive to price changes (inelastic) but became increasingly sensitive (elastic) as prices increased. Correlations between the demand indices at both administrations were very high magnitude and statistically significant (rs = .76-.99, ps < .001), and no significant within-subjects differences were present. CONCLUSIONS These findings provide initial support for the temporal stability of motivation for tobacco as measured by a CPT. Future studies with larger samples and timeframes will be important to verify these findings.

Dissociable brain signatures of choice conflict and immediate reward preferences in alcohol use disorders.

Impulsive delayed reward discounting (DRD) is an important behavioral process in alcohol use disorders (AUDs), reflecting incapacity to delay gratification. Recent work in neuroeconomics has begun to unravel the neural mechanisms supporting DRD, but applications of neuroeconomics in relation to AUDs have been limited. This study examined the neural mechanisms of DRD preferences in AUDs, with emphasis on dissociating activation patterns based on DRD choice type and level of cognitive conflict. Heavy drinking adult men with (n = 13) and without (n = 12) a diagnosis of an AUD completed a monetary DRD task during a functional magnetic resonance imaging scan. Participant responses were coded based on choice type (impulsive versus restrained) and level of cognitive conflict (easy versus hard). AUD+ participants exhibited significantly more impulsive DRD decision‐making. Significant activation during DRD was found in several decision‐making regions, including dorsolateral prefrontal cortex (DLPFC), insula, posterior parietal cortex (PPC), and posterior cingulate. An axis of cognitive conflict was also observed, with hard choices associated with anterior cingulate cortex and easy choices associated with activation in supplementary motor area. AUD+ individuals exhibited significant hyperactivity in regions associated with cognitive control (DLPFC) and prospective thought (PPC) and exhibited less task‐related deactivation of areas associated with the brains default network during DRD decisions. This study provides further clarification of the brain systems supporting DRD in general and in relation to AUDs.

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.

Individual Variation in Behavioral Economic Indices of the Relative Value of Alcohol: Incremental Validity in Relation to Impulsivity, Craving, and Intellectual Functioning

There is increasing interest in the role of individual variation in behavioral economic indices of the relative value of alcohol in relation to alcohol use and misuse. The aim of the present study was to investigate the importance of behavioral economic indices of demand for alcohol generated from an alcohol purchase task (APT), a task that measures estimated alcohol consumption and price sensitivity above and beyond established risk variables, including dimensions of impulsivity and craving for alcohol. In addition, the study examined the APT indices in relation to intellectual functioning. Hierarchical regressions revealed that the behavioral economic index of Omax and intellectual functioning were significantly and uniquely associated with weekly alcohol consumption. In contrast, Intensity, and craving for alcohol were uniquely associated with alcohol misuse. These results provide further support for the importance of behavioral economic indices of demand in relation to both alcohol use and alcohol misuse. Parallels to previous studies, limitations, and important future directions are discussed.

Interrelationships among parental family history of substance misuse, delay discounting, and personal substance use.

RationaleDespite consistent evidence of the familiality of substance misuse, the mechanisms by which family history (FH) increases the risk of addiction are not well understood. One behavioral trait that may mediate the risk for substance use and addiction is delay discounting (DD), which characterizes an individual’s preferences for smaller immediate rewards compared to larger future rewards.ObjectivesThe aim of this study is to examine the interrelationships among FH, DD, and diverse aspects of personal substance use, and to test DD as a mediator of the relationship between FH and personal substance use.MethodsThe study used crowdsourcing to recruit a community sample of adults (N = 732). Family history was assessed using a brief assessment of perceived parental substance use problems, personal substance use was assessed using the Alcohol Use Disorders Identification Test and a measure of frequency of use, and delay discounting was assessed using a latent index of discounting preferences across six reward magnitudes.ResultsSteeper discounting was significantly associated with personal alcohol, tobacco, and marijuana use, and level of substance experimentation. Steeper DD was also associated with a denser parental FH of alcohol, tobacco, and overall substance misuse. Parental FH density was significantly associated with several aspects of personal substance use, and these relationships were partially mediated by DD.ConclusionsThe current study suggests that impulsivity, as measured by DD, is one proximal mechanism by which parental FH increases substance use later in life. The causal role of DD in this relationship will need to be established in future longitudinal studies.

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.

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.

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.