Elizabeth R. Aston

Further validation of a marijuana purchase task

BACKGROUND A valid measure of the relative economic value of marijuana is needed to characterize individual variation in the drugs reinforcing value and inform evolving national marijuana policy. Relative drug value (demand) can be measured via purchase tasks, and demand for alcohol and cigarettes has been associated with craving, dependence, and treatment response. This study examined marijuana demand with a marijuana purchase task (MPT). METHODS The 22-item self-report MPT was administered to 99 frequent marijuana users (37.4% female, 71.5% marijuana use days, 15.2% cannabis dependent). RESULTS Pearson correlations indicated a negative relationship between intensity (free consumption) and age of initiation of regular use (r=-0.34, p<0.001), and positive associations with use days (r=0.26, p<0.05) and subjective craving (r=0.43, p<0.001). Omax (maximum expenditure) was positively associated with use days (r=0.29, p<0.01) and subjective craving (r=0.27, p<0.01). Income was not associated with demand. An exponential demand model provided an excellent fit to the data across users (R(2)=0.99). Group comparisons based on presence or absence of DSM-IV cannabis dependence symptoms revealed that users with any dependence symptoms showed significantly higher intensity of demand and more inelastic demand, reflecting greater insensitivity to price increases. CONCLUSIONS These results provide support for construct validity of the MPT, indicating its sensitivity to marijuana demand as a function of increasing cost, and its ability to differentiate between users with and without dependence symptoms. The MPT may denote abuse liability and is a valuable addition to the behavioral economic literature. Potential applications to marijuana pricing and tax policy are discussed.

Cue-elicited increases in incentive salience for marijuana: Craving, demand, and attentional bias.

BACKGROUND Incentive salience is a multidimensional construct that includes craving, drug value relative to other reinforcers, and implicit motivation such as attentional bias to drug cues. Laboratory cue reactivity (CR) paradigms have been used to evaluate marijuana incentive salience with measures of craving, but not with behavioral economic measures of marijuana demand or implicit attentional processing tasks. METHODS This within-subjects study used a new CR paradigm to examine multiple dimensions of marijuanas incentive salience and to compare CR-induced increases in craving and demand. Frequent marijuana users (N=93, 34% female) underwent exposure to neutral cues then to lit marijuana cigarettes. Craving, marijuana demand via a marijuana purchase task, and heart rate were assessed after each cue set. A modified Stroop task with cannabis and control words was completed after the marijuana cues as a measure of attentional bias. RESULTS Relative to neutral cues, marijuana cues significantly increased subjective craving and demand indices of intensity (i.e., drug consumed at

Marijuana's acute effects on cognitive bias for affective and marijuana cues.

0) and Omax (i.e., peak drug expenditure). Elasticity significantly decreased following marijuana cues, reflecting sustained purchase despite price increases. Craving was correlated with demand indices (rs: 0.23-0.30). Marijuana users displayed significant attentional bias for cannabis-related words after marijuana cues. Cue-elicited increases in intensity were associated with greater attentional bias for marijuana words. CONCLUSIONS Greater incentive salience indexed by subjective, behavioral economic, and implicit measures was observed after marijuana versus neutral cues, supporting multidimensional assessment. The study highlights the utility of a behavioral economic approach in detecting cue-elicited changes in marijuana incentive salience.

Co-use of Alcohol and Cannabis: A Review

Marijuana produces acute increases in positive subjective effects and decreased reactivity to negative affective stimuli, though may also acutely induce anxiety. Implicit attentional and evaluative processes may explicate marijuanas ability to acutely increase positive and negative emotions. This within-subjects study examined whether smoked marijuana with 2.7-3.0% delta-9-tetrahydrocannabinol (THC), relative to placebo, acutely changed attentional processing of rewarding and negative affective stimuli as well as marijuana-specific stimuli. On 2 separate days, regular marijuana users (N = 89) smoked placebo or active THC cigarette and completed subjective ratings of mood, intoxication, urge to smoke marijuana, and 2 experimental tasks: pleasantness rating (response latency and perceived pleasantness of affective and marijuana-related stimuli) and emotional Stroop (attentional bias to affective stimuli). On the pleasantness rating task, active marijuana increased response latency to negatively valenced and marijuana-related (vs. neutral) visual stimuli, beyond a general slowing of response. Active marijuana also increased pleasantness ratings of marijuana images, although to a lesser extent than placebo due to reduced marijuana urge after smoking. Overall, active marijuana did not acutely change processing of positive emotional stimuli. There was no evidence of attentional bias to affective word stimuli on the emotional Stroop task with the exception of attentional bias to positive word stimuli in the subgroup of marijuana users with cannabis dependence. Marijuana may increase allocation of attentional resources toward marijuana-specific and negatively valenced visual stimuli without altering processing of positively valenced stimuli. Marijuana-specific cues may be more attractive with higher levels of marijuana craving and less wanted with low craving levels.

Medicinal versus Recreational Cannabis Use among Returning Veterans.

Purpose of ReviewThe purpose of this review is to provide an overview of the existing literature on the relationship between the co-use of cannabis and alcohol including (1) epidemiology, comorbidity, and associated consequences of cannabis and alcohol use disorders; (2) preclinical and clinical laboratory studies examining behavioral pharmacology of cannabis and alcohol co-use; and (3) clinical outcomes related to co-use.Recent FindingsFindings from the literature reviewed suggest that the co-use of alcohol and cannabis is associated with additive performance impairment effects, higher and more frequent consumption levels, increased social and behavioral consequences such as driving while impaired, and greater likelihood of the experiencing comorbid substance use and mental health disorders. Furthermore, co-use may be associated with worse clinical outcomes, yet there are few studies examining the development and evaluation of interventions on reducing the co-use of cannabis and alcohol.SummaryThere is a need for more rigorous and longitudinal research studies on the co-use of cannabis and alcohol to glean a more complete understanding of the relationship between the two substances. Findings can be used to develop and refine intervention strategies to successfully reduce cannabis and alcohol co-use.

The Acute Effects of a Dopamine D3 Receptor Preferring Agonist on Motivation for Cigarettes in Dependent and Occasional Cigarette Smokers

Although increasing rates of cannabis use and cannabis use disorder (CUD) are well documented among veterans, little is known about their use of cannabis specifically for medicinal purposes. The present study characterizes such use and compares veterans reporting cannabis use for medicinal (n = 66) versus recreational (n = 77) purposes on (a) sociodemographic factors, (b) psychiatric disorders (posttraumatic stress disorder [PTSD], major depressive disorder [MDD], and CUD), (c) other substance use, (d) reasons for cannabis use and cannabis-related problems, and (e) physical and mental health. Participants were veterans deployed post 9/11/2001 recruited from a Veterans Health Administration (VHA) facility (N = 143; mean [SD] age = 30.0 [6.6]; mean [SD] deployments = 1.7 [1.1]) who reported past-year cannabis use. The most frequently endorsed conditions for medicinal cannabis (MC) use were anxiety/stress, PTSD, pain, depression, and insomnia. In logistic regression analyses adjusted for frequency of cannabis use, MC users were significantly more likely (odds ratio [OR] = 3.16) to meet criteria for PTSD than were recreational cannabis (RC) users. Relative to RC users, MC users reported significantly greater motivation for using cannabis to cope with sleep disturbance, as well as significantly poorer sleep quality and worse physical health. Veterans who use cannabis for medicinal purposes differ significantly in sleep, physical, and mental health functioning than do veterans who use cannabis for recreational purposes. PTSD and sleep problems may be especially relevant issues to address in screening and providing clinical care to returning veterans who are using cannabis for medicinal purposes.

Psychopathology and tobacco demand

Abstract Background Dopaminergic functioning is thought to play critical roles in both motivation and addiction. There is preliminary evidence that dopamine agonists reduce the motivation for cigarettes in smokers. However, the effects of pramipexole, a dopamine D3 receptor preferring agonist, have not been investigated. The aim of this study was to examine the effects of an acute dose of pramipexole on the motivation to earn cigarettes and nondrug rewards. Methods Twenty dependent and 20 occasional smokers received 0.5 mg pramipexole using a double-blind, placebo-controlled crossover design. Motivation for cigarettes and consummatory nondrug rewards was measured using the DReaM-Choice task, in which participants earned, and later “consumed,” cigarettes, music, and chocolate. Demand for cigarettes was measured using the Cigarette Purchase Task (CPT). Self-reported craving, withdrawal, and drug effects were also recorded. Results Dependent smokers chose (p < .001) and button-pressed for (p < .001) cigarettes more, and chose chocolate less (p < .001), than occasional smokers. Pramipexole did not affect the number of choices for or amount of button-pressing for any reward including cigarettes, which was supported by a Bayesian analysis. The dependent smokers had greater demand for cigarettes than occasional smokers across all CPT outcomes (ps < .021), apart from elasticity. Pramipexole did not affect demand for cigarettes, and this was supported by Bayesian analyses. Pramipexole produced greater subjective “feel drug” and “dislike drug” effects than placebo. Conclusions Dependent and occasional cigarette smokers differed in their motivation for cigarettes but not for the nondrug rewards. Pramipexole did not acutely alter motivation for cigarettes. These findings question the role of dopamine D3 receptors in cigarette-seeking behavior in dependent and occasional smokers. Implications This study adds to the growing literature about cigarette versus nondrug reward processing in nicotine dependence and the role of dopamine in cigarette-seeking behavior. Our results suggest nicotine dependence is associated with a hypersensitivity to cigarette rewards but not a hyposensitivity to nondrug rewards. Furthermore, our results question the importance of dopamine D3 receptors in motivational processing of cigarettes in occasional and dependent smokers.

Development and initial validation of a marijuana cessation expectancies questionnaire

INTRODUCTION Behavioral economic measurement of the relative value of tobacco (Cigarette Purchase Task; CPT) is used to examine individual differences in motivation for tobacco under certain contexts. Smokers with psychopathology, relative to those without, may demonstrate stronger demand for tobacco following a period of smoking deprivation, which could account for disparate rates of smoking and cessation among this subgroup. METHOD Participants (n=111) were community-recruited adult daily smokers who completed the CPT after a deprivation period of approximately 60min. Presence of psychopathology was assessed via clinical interview; 40.5% (n=45) of the sample met criteria for past-year psychological diagnosis. Specifically, 31.5% (n=35) had an emotional disorder (anxiety/depressive disorder), 17.1% (n=19) had a substance use disorder, and 19.1% of the sample had more than one disorder. RESULTS Smokers with any psychopathology showed significantly higher intensity (demand at unrestricted cost;

Distress Intolerance and Smoking Topography in the Context of a Biological Challenge

0) and Omax (peak expenditure for a drug) relative to smokers with no psychopathology. Intensity was significantly higher among smokers with an emotional disorder compared to those without. Smokers with a substance use disorder showed significantly higher intensity and Omax, and lower elasticity, reflecting greater insensitivity to price increases. Having≥2 disorders was associated with higher intensity relative to having 1 or no disorders. DISCUSSION Findings suggest that presence of psychopathology may be associated with greater and more persistent motivation to smoke. Future work is needed to explore the mechanism linking psychopathology to tobacco demand.

Interrelationships between marijuana demand and discounting of delayed rewards: Convergence in behavioral economic methods

BACKGROUND The present research examines anticipated consequences of ceasing or reducing marijuana use with initial development and psychometric validation of a measure of marijuana cessation expectancies. METHODS The 46-item Marijuana Cessation Expectancies Questionnaire (MCEQ) was initially developed from the content validity analysis of free responses about expected outcomes of stopping and decreasing marijuana use generated by 94 participants. The closed-ended MCEQ was subsequently administered to 151 non-treatment seeking regular marijuana users (used on M=64.7% of the prior 60days, SD=25.1%;Mage=21.4, SD=3.96; 38.4% female). RESULTS Exploratory factor analyses identified six MCEQ factors that accounted for 61% of variance, which were related to expected improvement in: 1) performance/motivation, 2) problems with authority, and 3) interpersonal functioning, and expected worsening of 4) mood states and 5) fun experiences, and 6) changes in appetite/weight from cessation/reduction of marijuana use. Internal consistency of full scale items was good (α=0.86) and moderate to high for all factors (αs=0.60-0.89). The MCEQ items showed good concurrent validity with key measures and incremental associations with change indices (prior history of cessation/reduction attempt, benefits of reduction, importance of change), beyond the effects of marijuana use expectancies. CONCLUSIONS These data provide initial support for the MCEQ and suggest it is closely linked to reduction/cessation decisions in marijuana users. MCEQ may be used clinically to enhance existing behavioral treatments and motivational interventions for problem marijuana use.