Plain cigarette packs do not exert Pavlovian to instrumental transfer of control over tobacco-seeking

Pavlovian-to-Instrumental Transfer across Mental Disorders: A Review

A mechanism known as Pavlovian-to-instrumental transfer (PIT) describes a phenomenon by which the values of environmental cues acquired through Pavlovian conditioning can motivate instrumental behavior. PIT may be one basic mechanism of action control that can characterize mental disorders on a dimensional level beyond current classification systems. Therefore, we review human PIT studies investigating subclinical and clinical mental syndromes. The literature prevails an inhomogeneous picture concerning PIT. While enhanced PIT effects seem to be present in non-substance-related disorders, overweight people, and most studies with AUD patients, no altered PIT effects were reported in tobacco use disorder and obesity. Regarding AUD and relapsing alcohol-dependent patients, there is mixed evidence of enhanced or no PIT effects. Additionally, there is evidence for aberrant corticostriatal activation and genetic risk, e.g., in association with high-risk alcohol consumption and relapse after alcohol detoxification. In patients with anorexia nervosa, stronger PIT effects elicited by low caloric stimuli were associated with increased disease severity. In patients with depression, enhanced aversive PIT effects and a loss of action-specificity associated with poorer treatment outcomes were reported. Schizophrenic patients showed disrupted specific but intact general PIT effects. Patients with chronic back pain showed reduced PIT effects. We provide possible reasons to understand heterogeneity in PIT effects within and across mental disorders. Further, we strengthen the importance of reliable experimental tasks and provide test-retest data of a PIT task showing moderate to good reliability. Finally, we point toward stress as a possible underlying factor that may explain stronger PIT effects in mental disorders, as there is some evidence that stress per se interacts with the impact of environmental cues on behavior by selectively increasing cue-triggered wanting. To conclude, we discuss the results of the literature review in the light of Research Domain Criteria, suggesting future studies that comprehensively assess PIT across psychopathological dimensions.

Helpless against food cues: the influence of pro- and anti-sugar videos on instrumental food-seeking behaviour in a Pavlovian-to-instrumental transfer paradigm

OBJECTIVE

External food cues can trigger food seeking by means of associative Stimulus-Outcome-Response learning mechanisms. These mechanisms can contribute to cued overeating. The present study aims at investigating if (cued) food-seeking behaviour can be influenced by pro- and anti-sugar videos.

DESIGN

Participants (N = 81) completed a Pavlovian-to-instrumental transfer (PIT) task: in an instrumental training, they learned associations between button presses and resulting sugary or sugar-free snacks. In a subsequent Pavlovian training, the snacks were paired with different cues. During the following transfer test, participants performed free button presses to win snacks while the cues were present or not.

MAIN OUTCOME MEASURES

The number of button presses for the different snacks in the transfer test was analysed.

RESULTS

We observed an outcome specific PIT effect, i.e. higher response rates for cued snacks. The videos did not affect the PIT effect. However, exploratory analyses revealed that the anti-sugar video led to fewer button presses for sugary snacks (compared to the pro-sugar video).

CONCLUSION

While snack-seeking behaviour was unaffected by the video's messages in the presence of food cues, in the absence of food cues there was evidence for a reduction of sugary snack choices by the anti-sugar video.

Vapers exhibit similar subjective nicotine dependence but lower nicotine reinforcing value compared to smokers

INTRODUCTION

E-cigarette use has increased rapidly over the last 10 years, mostly among smokers and ex-smokers. Although there may be some degree of dependency on nicotine via e-cigarette use, the nature of this dependency is poorly understood. The aim of this paper is to use tasks from behavioural economics to compare the value that smokers place on tobacco cigarettes to the value that vapers place on e-cigarettes.

METHOD

Exclusive current smokers (n = 25) and vapers (n = 20) attended one session where they completed the Cigarette/e-cigarette Dependence Scale, the Cigarette/e-cigarette Purchasing Task (CPT) and the Concurrent Choice Task (CCT). The CPT requires participants to indicate how many puffs of their chosen product they would purchase at increasing price points. The CCT requires participants to choose between earning a money point or a point towards a cigarette/e-cigarette after being presented with a neutral, money or cigarette/e-cigarette cue.

RESULTS

Overall scores on the self-report scales suggest a comparable level of dependency between smokers and vapers. The CPT revealed that vapers are more sensitive than smokers to escalating costs as consumption declined as costs increased. On the CCT, when primed with money, vapers showed a decrease in choosing e-cigarettes.

CONCLUSION

These findings suggest that, on behavioural economic tasks, tobacco cigarettes have a higher relative value than e-cigarettes. Vapers appear to place a lower limit on what they will spend to access e-cigarettes and more readily choose money over e-cigarette puffs when primed by money cues.

Relative expected value of drugs versus competing rewards underpins vulnerability to and recovery from addiction

Behavioural economic theories of addiction contend that greater expected value of drug relative to alternative non-drug rewards is the core mechanism underpinning vulnerability to and recovery from addiction. To evaluate this claim, we exhaustively review studies with human drug users that have measured concurrent choice between drugs vs. alternative rewards, and explored individual differences. These studies show that drug choice can be modulated by drug cues, drug devaluation, imposition of costs/punishment and negative mood induction. Regarding individual differences, dependence severity was reliably associated with overall drug preference, and self-reported drug use to cope with negative affect was reliably associated with greater sensitivity to mood induced increases in drug choice. By contrast, there were no reliable individual differences in sensitivity to the effect of drug cues, drug devaluation or punishment on drug choice. These findings provide insight into the mechanisms that underpin vulnerability to dependence: vulnerability is conferred by greater relative value ascribed to drugs, and relative drug value is further augmented by negative affective states in those who report drug use coping motives. However, dependence does not appear to be characterised by abnormal cue-reactivity, habit learning or compulsion. We then briefly review emerging literature which demonstrates that therapeutic interventions and recovery from addiction might be attributed to changes in the expected relative value of drug versus alternative rewards. Finally, we outline a speculative computational account of the distortions in decision-making that precede action selection in addiction, and we explain how this account provides a blueprint for future research on the determinants of drug choice, and mechanisms of treatment and recovery from addiction. We conclude that a unified economic decision-making account of addiction has great promise in reconciling diverse addiction theories, and neuropsychological evaluation of the underlying decision mechanisms is a fruitful area for future research and treatment.

Intact corticostriatal control of goal-directed action in Alcohol Use Disorder: a Pavlovian-to-instrumental transfer and outcome-devaluation study

Deficits in instrumental, goal-directed control, combined with the influence of drug-associated Pavlovian-conditioned stimuli, are thought to influence the development and maintenance of addiction. However, direct evidence has mainly come from animal studies. We sought to establish whether alcohol use disorder (AUD) is characterized by behavioral or neurobiological deficits in (i) the integration of Pavlovian and instrumental values and (ii) goal-directed control; and (iii) whether duration or severity of AUD is associated with such deficits. The influence of cues predicting food rewards on instrumental action was assessed in a Pavlovian-to-instrumental transfer (PIT) test, measuring both specific and general PIT, and goal-directed behavior in an outcome-devaluation test. Brain activity was measured using functional MRI in 38 abstinent individuals with AUD and 22 matched healthy control individuals (HCs). We found significant specific and general PIT and outcome-devaluation effects across groups indicating goal-directed control, mediated by distinct corticostriatal signals, but no significant differences between individuals with AUD and healthy controls. Bayesian analyses provided substantial-to-strong evidence for the absence of group differences for these effects, or any relationship with duration or severity of AUD. These results suggest intact ability to integrate action-outcome associations on specific and general PIT and goal-directed learning in AUD during abstinence.

An Adaptation of Pavlovian-to-Instrumental Transfer (PIT) Methodology to Examine the Energizing Effects of Reward-Predicting Cues on Behavior in Young Adults

There is growing recognition that much of human behavior is governed by the presence of classically conditioned cues. The Pavlovian-to-Instrumental Transfer (PIT) paradigm offers a way to measure the effects of classically conditioned stimuli on behavior. In the current study, a novel behavioral task, an adaptation of the PIT framework, was developed for use in conjunction with an fMRI classical conditioning task. Twenty-four healthy young adults completed (1) instrumental training, (2) Pavlovian conditioning, and (3) a Transfer test. During instrumental training, participants learned to apply force to a handgrip to win money from slot machines pictured on a computer screen. During Pavlovian conditioning, slot machines appeared with one of two abstract symbols (cues), one symbol was predictive of monetary reward. During the Transfer test, participants again applied force to a handgrip to win money. This time, the slot machines were presented with the Pavlovian cues, but with the outcomes hidden. The results indicated increased effort on the instrumental task, i.e. higher response frequency and greater force, in the presence of the reward-predicting cue. Our findings add to the growing number of studies demonstrating PIT effects in humans. This new paradigm is effective in measuring the effects of a conditioned stimulus on behavioral activation.

Does acute stress influence the Pavlovian-to-instrumental transfer effect? Implications for substance use disorders

RATIONAL

The ability of conditioned stimuli to affect instrumental responding is a robust finding from animal as well as human research and is assumed as a key factor regarding the development and maintenance of addictive behaviour.

OBJECTIVES

While it is well known that stress is an important factor for relapse after treatment, little is known about the impact of stress on conditioned substance-associated stimuli and their influence on instrumental responding.

METHODS

We administered in the present study a Pavlovian-to-instrumental transfer (PIT) paradigm with stimuli associated with smoking- and chocolate-related rewards using points in a token economy to light to moderate smokers who also indicated to like eating chocolate. After completion of the first two phases of the PIT paradigm (i.e. Pavlovian training and instrumental trainings), participants were randomly allocated to the socially evaluated cold pressor test or a control condition before the final phase of the PIT paradigm, the transfer phase, was administered.

RESULTS

The presentation of a smoking-related stimulus enhanced instrumental responding for a smoking-related reward (i.e. 'smoking-PIT' effect) and presentation of a chocolate-related stimulus for a chocolate-related reward (i.e. 'chocolate-PIT' effect) in participants aware of the experimental contingencies as indicated by expectancy ratings. However, acute stress did not change (i.e. neither enhanced nor attenuated) the 'smoking-PIT' effect or the 'chocolate-PIT' effect, and no overall effect of acute stress on tobacco choice was observed in aware participants.

CONCLUSIONS

The established role of stress in addiction appears not to be driven by an augmenting effect on the ability of drug stimuli to promote drug-seeking.

Nucleus Accumbens Cholinergic Interneurons Oppose Cue-Motivated Behavior

BACKGROUND

Environmental reward-predictive stimuli provide a major source of motivation for adaptive reward pursuit behavior. This cue-motivated behavior is known to be mediated by the nucleus accumbens (NAc) core. The cholinergic interneurons in the NAc are tonically active and densely arborized and thus well suited to modulate NAc function. However, their causal contribution to adaptive behavior remains unknown. Here we investigated the function of NAc cholinergic interneurons in cue-motivated behavior.

METHODS

We used chemogenetics, optogenetics, pharmacology, and a translationally analogous Pavlovian-to-instrumental transfer behavioral task designed to assess the motivating influence of a reward-predictive cue over reward-seeking actions in male and female rats.

RESULTS

The data show that NAc cholinergic interneuron activity critically opposes the motivating influence of appetitive cues. Chemogenetic inhibition of NAc cholinergic interneurons augmented cue-motivated behavior. Optical stimulation of acetylcholine release from NAc cholinergic interneurons prevented cues from invigorating reward-seeking behavior, an effect that was mediated by activation of β2-containing nicotinic acetylcholine receptors.

CONCLUSIONS

NAc cholinergic interneurons provide a critical regulatory influence over adaptive cue-motivated behavior and therefore are a potential therapeutic target for the maladaptive cue-motivated behavior that marks many psychiatric conditions, including addiction and depression.

Single-response appetitive Pavlovian to instrumental transfer is suppressed by aversive counter-conditioning

Environmental stimuli, when paired with reward, can influence behaviour in maladaptive ways, for example, by encouraging overeating or addiction. Such behaviour can be sensitive to reward value manipulations, under circumscribed conditions, but whether reward-seeking is also sensitive to stimulus value manipulations remains unclear. Thus, the current experiment investigated whether reducing the hedonic value of a reward-paired stimulus would reduce reward-seeking behaviour. In total, 36 participants successfully completed a single-response Pavlovian-instrumental transfer (PIT) task with a counter-conditioning procedure. The Pavlovian phase associated three conditioned stimuli (CSs) with money at 100%, 50%, or 0% contingency. Counter-conditioning then followed for the experimental group, who saw the 100% CS paired with unpleasant pictures, while the control group saw only neutral images. Instrumental training required participants to learn a button-pressing response to win money. The transfer phase contrasted instrumental responding during baseline and CS presentation. Both experimental and control groups liked the 100% CS more than the other CSs after Pavlovian training, but counter-conditioning reduced this 100% CS liking. In transfer, the experimental group showed an abolition of appetitive PIT, while the control group showed maintenance of appetitive PIT. However, this group difference was only evident in response vigour, not response initiation. In summary, CS hedonic value influences cue-potentiated instrumental responding. More specifically, hedonic value of a reward-paired cue influences the vigour of instrumental responses, but not the decision to initiate a response. These data may have relevance to smoking cessation policies, where the introduction of health warnings may be viewed as a real-world example of counter conditioning.

Pavlovian to Instrumental Transfer Responses Do Not Correlate With Addiction-Like Behavior in Rats

Pavlovian learning plays a prominent role in the etiology of addiction. The influence of Pavlovian conditioning on the expression of an instrumental response can be studied using the Pavlovian-to-instrumental transfer (PIT) paradigm. This paradigm consists of independent Pavlovian conditioning and instrumental training prior to the combination of both during the test. During this test, the reward is not available, and an increase in the instrumental responding during conditioned stimuli presentation is a measure of PIT. Recent studies have reported a higher PIT in alcohol and nicotine dependent patients, suggesting that enhanced PIT might be a marker for dependence vulnerability. However, these studies did not use standard PIT procedures, and a clear correlation between an enhanced PIT and drug-related and addictive behaviors has so far not been demonstrated. For a systematic evaluation rats were trained in a cocaine addiction model. Addicted-like and non-addicted-like rats were subsequently assessed in the PIT paradigm. In a further experiment, rats were first tested in the PIT paradigm and thereafter subjected to cocaine self-administration (CSA) training. Our results revealed that addicted-like rats did not differ from non-addicted-like in their performance in the PIT test. However, CSA behavior showed a positive correlation with PIT. This data suggests that stronger PIT may predict higher motivational impact of conditioned stimuli on drug self-administration and improved learning of drug-cue association rather than the risk to develop addiction as such.

Appetitive Pavlovian-to-Instrumental Transfer in Participants with Normal-Weight and Obesity

Altered eating behavior due to modern, food-enriched environments has a share in the recent obesity upsurge, though the exact mechanisms remain unclear. This study aims to assess whether higher weight or weight gain are related to stronger effects of external cues on motivation-driven behavior. 51 people with and without obesity completed an appetitive Pavlovian-to-Instrumental Transfer (PIT) paradigm. During training, button presses as well as presentation of fractal images resulted in three palatable and one neutral taste outcome. In the subsequent test phase, outcome-specific and general behavioral bias of the positively associated fractal images on deliberate button press were tested under extinction. While all participants showed signs of specific transfer, general transfer was not elicited. Contrary to our expectations, there was no main effect of weight group on PIT magnitude. Participants with obesity exhibited higher scores in the Three-Factor Eating Questionnaire Disinhibition scale, replicating a very robust effect from previous literature. Individual Restraint scores were able to predict body-mass index (BMI) change after a three-year period. Our data indicate that PIT is an important player in how our environment influences the initiation of food intake, but its effects alone cannot explain differences in-or future development of-individual weight.

Tweeting about public health policy: Social media response to the UK Government's announcement of a Parliamentary vote on draft standardised packaging regulations

BACKGROUND

Standardised tobacco packaging has been, and remains, a contentious policy globally, attracting corporate, public health, political, media and popular attention. In January 2015, the UK Government announced it would vote on draft regulations for the policy before the May 2015 General Election. We explored reactions to the announcement on Twitter, in comparison with an earlier period of little UK Government activity on standardised packaging.

METHODS

We obtained a random sample of 1038 tweets in two 4-week periods, before and after the UK Government's announcement. Content analysis was used to examine the following Tweet characteristics: support for the policy, purpose, Twitter-user's geographical location and affiliation, and evidence citation and quality. Chi-squared analyses were used to compare Tweet characteristics between the two periods.

RESULTS

Overall, significantly more sampled Tweets were in favour of the policy (49%) in comparison to those opposed (19%). Yet, at Time 2, following the announcement, a greater proportion of sampled tweets opposed standardised packaging compared to the period sampled at Time 1, prior to the announcement (p<0.001). The quality of evidence and research cited in URLs linked at Time 2 was significantly lower than at Time 1 (p<0.001), with peer-reviewed research more likely to be shared in positive Tweets (p<0.001) and in Tweets linking to URLs originating from the health sector (p<0.001). The decline in the proportion of positive Tweets was mirrored by a reduction in Tweets by health sector Twitter-users at Time 2 (p<0.001).

CONCLUSIONS

Microblogging sites can reflect offline policy debates and are used differently by policy proponents and opponents dependent on the policy context. Twitter-users opposed to standardised packaging increased their activity following the Government's announcement, while those in support broadly maintained their rate of Twitter engagement. The findings offer insight into the public health community's options for using Twitter to influence policy and disseminate research. In particular, proliferation of Twitter activity following pro-public health policy announcements could be considered to ensure pro-health messages are not overshadowed by anti-regulation voices.

The latent trait of ICD-11 nicotine dependence criteria: Dimensional and categorical phenotypes

We aimed to identify phenotypes of DSM-ICD nicotine dependence among a representative sample of lifetime weekly smokers in the largest metropolitan area in South America. Data came from 1,387 lifetime weekly smokers in the São Paulo Megacity Mental Health Survey. We used exploratory factor analysis (EFA) and latent class analysis (LCA) on ICD-11 nicotine dependence proposed criteria to explore dimensionality and phenotypes profiles, followed by logistic regression models to examine the association between latent classes and socio-demographic, psychiatric and chronic medical conditions. Analyses were performed using Mplus taking into account the complex survey design features. An unidimensional model had the best EFA fit with high loadings on all criteria. Response patterns detected by LCA indicated class differences based on severity continuum: a "non-symptomatic class" (32.0%), a "low-moderate symptomatic class" (34.9%)-with high probability of the criterion "use in larger amounts", and a "high-moderate symptomatic class" (33.1%). We found an association between high-income and the intermediate class that differs from findings in high-income countries, and high likelihood of psychiatric comorbidity among the most symptomatic smokers. The best dimensional model that pulled together nicotine dependence criteria supported a single factor, in concordance with the changes proposed for ICD-11.

Associative mechanisms involved in specific Pavlovian-to-instrumental transfer in human learning tasks

Four experiments compared the effect of forward and backward conditioning procedures on the ability of conditioned stimuli (CS) to elevate instrumental responding in a Pavlovian-to-instrumental transfer (PIT) task. Two responses were each trained with one distinct outcome (R1->O1, R2->O2), either concurrently (Experiment 1) or separately (Experiments 2, 3 and 4). Then, in Experiments 1 and 2, four CSs were either followed or preceded by one outcome (A->O1, B->O2, O1->C, O2->D). In Experiment 3, each CS was preceded and followed by an outcome: for one group of participants, both outcomes were identical (e.g., O1->A->O1, O2->B->O2), but for the other, they were different (e.g., O1->A->O2, O2->B->O1). In Experiment 4, two CSs were preceded and followed by identical outcomes, and two CSs by different outcomes. In the PIT tests, participants performed R1 and R2 in the presence and absence of the CSs. In Experiments 1 and 2, only the CSs followed by outcomes in Pavlovian training elevated responding. In Experiments 3 and 4, all the CSs elevated responding but based on the outcome that followed them in training. These results support the stimulus-outcome-response (S-O-R) mechanism of specific PIT, according to which CSs elevate responding via activation of its associated outcome representation.

Cancer Patients Enrolled in a Smoking Cessation Clinical Trial: Characteristics and Correlates of Smoking Rate and Nicotine Dependence

Introduction

A substantial proportion of cancer patients continue to smoke after their diagnosis but few studies have evaluated correlates of nicotine dependence and smoking rate in this population, which could help guide smoking cessation interventions.

Aim

This study evaluated correlates of smoking rate and nicotine dependence among 207 cancer patients.

Methods

A cross-sectional analysis using multiple linear regression evaluated disease, demographic, affective, and tobacco-seeking correlates of smoking rate and nicotine dependence. Smoking rate was assessed using a timeline follow-back method. The Fagerström Test for Nicotine Dependence measured levels of nicotine dependence.

Results

A multiple linear regression predicting nicotine dependence showed an association with smoking to alleviate a sense of addiction from the Reasons for Smoking scale and tobacco-seeking behavior from the concurrent choice task (p < .05), but not with affect measured by the HADS and PANAS (p > .05). Multiple linear regression predicting prequit showed an association with smoking to alleviate addiction (p < .05). ANOVA showed that Caucasian participants reported greater rates of smoking compared to other races.

Conclusions

The results suggest that behavioral smoking cessation interventions that focus on helping patients to manage tobacco-seeking behavior, rather than mood management interventions, could help cancer patients quit smoking.

Beyond Cue Reactivity: Non-Drug-Related Motivationally Relevant Stimuli Are Necessary to Understand Reactivity to Drug-Related Cues

Neurobiological models of addiction posit that drug use can alter reward processes in two ways: (1) by increasing the motivational relevance of drugs and drug-related cues and (2) by reducing the motivational relevance of non-drug-related rewards. Here, we discuss the results from a series of neuroimaging studies in which we assessed the extent to which these hypotheses apply to nicotine dependence. In these studies, we recorded smokers’ and nonsmokers’ brain responses to a wide array of motivationally relevant visual stimuli that included pleasant, unpleasant, cigarette-related, and neutral images. Based on these findings, we highlight the flaws of the traditional cue reactivity paradigm and we conclude that responses to non-drug-related motivationally relevant stimuli should be used to appropriately gauge the motivational relevance of cigarette-related cues and to identify smokers attributing higher motivational relevance to drug-related cues than to non-drug-related rewards. Identifying these individuals is clinically relevant as they achieve lower rates of long-term smoking abstinence when attempting to quit. Finally, we show how this approach may be extended beyond nicotine dependence to inform theoretical and clinical research in the study of obesity.

Implications

The cue reactivity paradigm (ie, comparing responses evoked by drug-related cues to those evoked by neutral cues) cannot provide conclusive information about the motivational relevance of drug-related cues. Responses to non-drug-related motivationally relevant stimuli should be used to appropriately gauge the level of motivational relevance that substance-dependent individuals attribute to drug-related cues.

Pavlovian-to-Instrumental Transfer of Nicotine and Food Cues in Deprived Cigarette Smokers

Introduction

Smoking-related cues can promote drug-seeking behavior and curtail attempts to quit. One way to understand the potential impact of such cues is to compare cue-elicited behaviors for smoking and other reinforcers (eg, food) using the Pavlovian-to-instrumental transfer paradigm, which measures how much control cues can exert over reward-seeking responses.

Methods

We tested the influence of appetitive cues on smokers' behavior following 12 hours of abstinence from smoking and eating. First, we equated the value of cigarette and food by assessing a Willingness-to-Pay measure for each reinforcer. Second, we evaluated behavioral differences between cues with Pavlovian-to-instrumental transfer. In two phases, participants learned (1) the association between distinct stimuli and cigarette or food outcomes and, (2) specific instrumental responses that yielded such outcomes. Motivated behavior was probed under extinction in a subsequent transfer test assessing instrumental responding in the presence of the cues.

Results

Participants showed an increase in specific responding (eg, instrumental response associated with cigarette) when faced with the corresponding appetitive cue (eg, stimulus associated with cigarette) despite absence of outcome. Notably, they made more cigarette-seeking than food-seeking instrumental responses, suggesting that cues representative of cigarette outcomes exert stronger influences on behavior than non-drug (food) cues. Using a measure of subjective preference, we also observed that greater preference for cigarette-compared to food-cues correlated with increased cigarette-seeking behavior in the test phase.

Conclusion

Taken together, these results highlight how drug and non-drug cues differentially influence reward-seeking behaviors during deprivation, which has implications for smoking cessation treatment and relapse.

Implications

This study examines the motivational influence of both drug and non-drug cues within a single sample of cigarette smokers. Our results demonstrate that the motivational properties of smoking cues differ from cues relating to other types of reward, such as food. This research informs smoking cessation programs to target the salience of nicotine cues and the maladaptive drug-seeking behaviors prompted by them.

Drug cue reactivity involves hierarchical instrumental learning: evidence from a biconditional Pavlovian to instrumental transfer task

RATIONALE

Drug cue reactivity plays a crucial role in addiction, yet the underlying mechanisms are poorly understood. According to the binary associative account, drug stimuli retrieve an expectation of the drug outcome, which, in turn, elicits the associated drug-seeking response (S-O-R). By contrast, according to the hierarchical account, drug stimuli retrieve an expectation that the contingency between the drug-seeking response and the drug outcome is currently more effective, promoting performance of the drug-seeking response (S:R-O).

METHODS

The current study discriminated between these two accounts using a biconditional Pavlovian-to-instrumental transfer (PIT) task with 128 alcohol drinkers. A biconditional discrimination was first trained in which two responses produced alcohol and food outcomes, respectively, and these response-outcome contingencies were reversed across two discriminative stimuli (SDs). In the PIT test, alcohol and food cues were compounded with the two SDs to examine their impact on percent alcohol choice in extinction.

RESULTS

It was found that alcohol and food cues selectively primed choice of the response that earned that outcome in each SD (p < .001), and this effect was associated with participants' belief that cues signalled greater effectiveness of that response (p < .0001).

CONCLUSIONS

The alcohol stimulus could not have selectively primed the alcohol-seeking response through binary S-O-R associations because the drug outcome was equally associated with both responses. Rather, the alcohol stimulus must have retrieved an expectation that the response-alcohol contingency available in the current context was more likely to be effective (S:R-O), which primed performance of the alcohol-seeking response.

Packaging colour research by tobacco companies: the pack as a product characteristic

BACKGROUND

Tobacco companies use colour on cigarette packaging and labelling to communicate brand imagery, diminish health concerns, and as a replacement for prohibited descriptive words ('light' and 'mild') to make misleading claims about reduced risks.

METHODS

We analysed previously secret tobacco industry documents to identify additional ways in which cigarette companies tested and manipulated pack colours to affect consumers' perceptions of the cigarettes' flavour and strength.

RESULTS

Cigarette companies' approach to package design is based on 'sensation transference' in which consumers transfer sensations they derive from the packaging to the product itself. Companies manipulate consumers' perceptions of the taste and strength of cigarettes by changing the colour of the packaging. For example, even without changes to the tobacco blends, flavourings or additives, consumers perceive the taste of cigarettes in packages with red and darker colours to be fuller flavoured and stronger, and cigarettes in packs with more white and lighter colours are perceived to taste lighter and be less harmful.

CONCLUSIONS

Companies use pack colours to manipulate consumers' perceptions of the taste, strength and health impacts of the cigarettes inside the packs, thereby altering their characteristics and effectively creating new products. In countries that do not require standardised packaging, regulators should consider colour equivalently to other changes in cigarette characteristics (eg, physical characteristics, ingredients, additives and flavourings) when making determinations about whether or not to permit new products on the market.

Tobacco packaging design for reducing tobacco use

BACKGROUND

Tobacco use is the largest single preventable cause of death and disease worldwide. Standardised tobacco packaging is an intervention intended to reduce the promotional appeal of packs and can be defined as packaging with a uniform colour (and in some cases shape and size) with no logos or branding, apart from health warnings and other government-mandated information, and the brand name in a prescribed uniform font, colour and size. Australia was the first country to implement standardised tobacco packaging between October and December 2012, France implemented standardised tobacco packaging on 1 January 2017 and several other countries are implementing, or intending to implement, standardised tobacco packaging.

OBJECTIVES

To assess the effect of standardised tobacco packaging on tobacco use uptake, cessation and reduction.

SEARCH METHODS

We searched MEDLINE, Embase, PsycINFO and six other databases from 1980 to January 2016. We checked bibliographies and contacted study authors to identify additional peer-reviewed studies.

SELECTION CRITERIA

Primary outcomes included changes in tobacco use prevalence incorporating tobacco use uptake, cessation, consumption and relapse prevention. Secondary outcomes covered intermediate outcomes that can be measured and are relevant to tobacco use uptake, cessation or reduction. We considered multiple study designs: randomised controlled trials, quasi-experimental and experimental studies, observational cross-sectional and cohort studies. The review focused on all populations and people of any age; to be included, studies had to be published in peer-reviewed journals. We examined studies that assessed the impact of changes in tobacco packaging such as colour, design, size and type of health warnings on the packs in relation to branded packaging. In experiments, the control condition was branded tobacco packaging but could include variations of standardised packaging.

DATA COLLECTION AND ANALYSIS

Screening and data extraction followed standard Cochrane methods. We used different 'Risk of bias' domains for different study types. We have summarised findings narratively.

MAIN RESULTS

Fifty-one studies met our inclusion criteria, involving approximately 800,000 participants. The studies included were diverse, including observational studies, between- and within-participant experimental studies, cohort and cross-sectional studies, and time-series analyses. Few studies assessed behavioural outcomes in youth and non-smokers. Five studies assessed the primary outcomes: one observational study assessed smoking prevalence among 700,000 participants until one year after standardised packaging in Australia; four studies assessed consumption in 9394 participants, including a series of Australian national cross-sectional surveys of 8811 current smokers, in addition to three smaller studies. No studies assessed uptake, cessation, or relapse prevention. Two studies assessed quit attempts. Twenty studies examined other behavioural outcomes and 45 studies examined non-behavioural outcomes (e.g. appeal, perceptions of harm). In line with the challenges inherent in evaluating standardised tobacco packaging, a number of methodological imitations were apparent in the included studies and overall we judged most studies to be at high or unclear risk of bias in at least one domain. The one included study assessing the impact of standardised tobacco packaging on smoking prevalence in Australia found a 3.7% reduction in odds when comparing before to after the packaging change, or a 0.5 percentage point drop in smoking prevalence, when adjusting for confounders. Confidence in this finding is limited, due to the nature of the evidence available, and is therefore rated low by GRADE standards. Findings were mixed amongst the four studies assessing consumption, with some studies finding no difference and some studies finding evidence of a decrease; certainty in this outcome was rated very low by GRADE standards due to the limitations in study design. One national study of Australian adult smoker cohorts (5441 participants) found that quit attempts increased from 20.2% prior to the introduction of standardised packaging to 26.6% one year post-implementation. A second study of calls to quitlines provides indirect support for this finding, with a 78% increase observed in the number of calls after the implementation of standardised packaging. Here again, certainty is low. Studies of other behavioural outcomes found evidence of increased avoidance behaviours when using standardised packs, reduced demand for standardised packs and reduced craving. Evidence from studies measuring eye-tracking showed increased visual attention to health warnings on standardised compared to branded packs. Corroborative evidence for the latter finding came from studies assessing non-behavioural outcomes, which in general found greater warning salience when viewing standardised, than branded packs. There was mixed evidence for quitting cognitions, whereas findings with youth generally pointed towards standardised packs being less likely to motivate smoking initiation than branded packs. We found the most consistent evidence for appeal, with standardised packs rating lower than branded packs. Tobacco in standardised packs was also generally perceived as worse-tasting and lower quality than tobacco in branded packs. Standardised packaging also appeared to reduce misperceptions that some cigarettes are less harmful than others, but only when dark colours were used for the uniform colour of the pack.

AUTHORS' CONCLUSIONS

The available evidence suggests that standardised packaging may reduce smoking prevalence. Only one country had implemented standardised packaging at the time of this review, so evidence comes from one large observational study that provides evidence for this effect. A reduction in smoking behaviour is supported by routinely collected data by the Australian government. Data on the effects of standardised packaging on non-behavioural outcomes (e.g. appeal) are clearer and provide plausible mechanisms of effect consistent with the observed decline in prevalence. As standardised packaging is implemented in different countries, research programmes should be initiated to capture long term effects on tobacco use prevalence, behaviour, and uptake. We did not find any evidence suggesting standardised packaging may increase tobacco use.

Neural mechanisms underlying visual attention to health warnings on branded and plain cigarette packs

AIMS

To (1) test if activation in brain regions related to reward (nucleus accumbens) and emotion (amygdala) differ when branded and plain packs of cigarettes are viewed, (2) test whether these activation patterns differ by smoking status and (3) examine whether activation patterns differ as a function of visual attention to health warning labels on cigarette packs.

DESIGN

Cross-sectional observational study combining functional magnetic resonance imaging (fMRI) with eye-tracking. Non-smokers, weekly smokers and daily smokers performed a memory task on branded and plain cigarette packs with pictorial health warnings presented in an event-related design.

SETTING

Clinical Research and Imaging Centre, University of Bristol, UK.

PARTICIPANTS

Non-smokers, weekly smokers and daily smokers (n = 72) were tested. After exclusions, data from 19 non-smokers, 19 weekly smokers and 20 daily smokers were analysed.

MEASUREMENTS

Brain activity was assessed in whole brain analyses and in pre-specified masked analyses in the amygdala and nucleus accumbens. On-line eye-tracking during scanning recorded visual attention to health warnings.

FINDINGS

There was no evidence for a main effect of pack type or smoking status in either the nucleus accumbens or amygdala, and this was unchanged when taking account of visual attention to health warnings. However, there was evidence for an interaction, such that we observed increased activation in the right amygdala when viewing branded as compared with plain packs among weekly smokers (P = 0.003). When taking into account visual attention to health warnings, we observed higher levels of activation in the visual cortex in response to plain packaging compared with branded packaging of cigarettes (P = 0.020).

CONCLUSIONS

Based on functional magnetic resonance imaging and eye-tracking data, health warnings appear to be more salient on 'plain' cigarette packs than branded packs.

Food-Predicting Stimuli Differentially Influence Eye Movements and Goal-Directed Behavior in Normal-Weight, Overweight, and Obese Individuals

Obese individuals have been shown to exhibit abnormal sensitivity to rewards and reward-predicting cues as for example food-associated cues frequently used in advertisements. It has also been shown that food-associated cues can increase goal-directed behavior but it is currently unknown, whether this effect differs between normal-weight, overweight, and obese individuals. Here, we investigate this question by using a Pavlovian-to-instrumental transfer (PIT) task in normal-weight (N = 20), overweight (N = 17), and obese (N = 17) individuals. Furthermore, we applied eye tracking during Pavlovian conditioning to measure the participants' conditioned response as a proxy of the incentive salience of the predicted reward. Our results show that the goal-directed behavior of overweight individuals was more strongly influenced by food-predicting cues (i.e., stronger PIT effect) than that of normal-weight and obese individuals (p < 0.001). The weight groups were matched for age, gender, education, and parental education. Eye movements during Pavlovian conditioning also differed between weight categories (p < 0.05) and were used to categorize individuals based on their fixation style into "high eye index" versus "low eye index" as well. Our main finding was that the fixation style exhibited a complex interaction with the weight category. Furthermore, we found that normal-weight individuals of the group "high eye index" had higher body mass index within the healthy range than individuals of the group "low eye index" (p < 0.001), but this relationship was not found within in the overweight or obese groups (p > 0.646). Our findings are largely consistent with the incentive sensitization theory predicting that overweight individuals are more susceptible to food-related cues than normal-weight controls. However, this hypersensitivity might be reduced in obese individuals, possibly due to habitual/compulsive overeating or differences in reward valuation.

The propositional basis of cue-controlled reward seeking

Two experiments examined the role of propositional and automatic (ideomotor) processes in cue-elicited responding for rewarding outcomes (beer and chocolate). In a training phase, participants earned either chocolate or beer points by making one of two button-press responses. Rewards were indicated by the presentation of chocolate and beer pictures. On test, each trial began with a picture of beer or chocolate, or a blank screen, and choice of the beer versus chocolate response was assessed in the presence of these three pictures. Participants tended to choose the beer and chocolate response in the presence of the beer and chocolate pictures, respectively. In Experiment 1, instructions signalling that the pictures did not indicate which response would be rewarded significantly reduced the priming effect. In Experiment 2, instructions indicating that the pictures signified which response would not be rewarded resulted in a reversed priming effect. Finally, in both experiments, the priming effect correlated with self-reported beliefs that the cues signalled which response was more likely to be reinforced. These results suggest that cue-elicited response selection is mediated by a propositional belief regarding the efficacy of the response–outcome relationship, rather than an automatic ideomotor mechanism.

Analysis of the Paternalistic Justification of an Agenda Setting Public Health Policy: The Case of Tobacco Plain Packaging

This article analyses the paternalistic justification of the world's first mandatory tobacco plain packaging policy, which came into force in Australia in 2012. The policy is setting international precedence, with a range of developed and developing countries planning and implementing similar policies. Understanding the paternalistic dimension of the policy is therefore of imminent international importance. The policy meets important ethical benchmarks such as respect for citizens' self-interests and protection of others against harm. However, plain packaging faces a number of ethical challenges: the policy is a controversial type of paternalism; it runs partially against the harm principle; and it fails to meet key operational criteria.

Nucleus accumbens core dopamine signaling tracks the need-based motivational value of food-paired cues

Environmental reward-predictive stimuli provide a major source of motivation for instrumental reward-seeking activity and this has been linked to dopamine signaling in the nucleus accumbens (NAc) core. This cue-induced incentive motivation can be quite general, not restricted to instrumental actions that earn the same unique reward, and is also typically regulated by one's current need state, such that cues only motivate actions when this is adaptive. But it remains unknown whether cue-evoked dopamine signaling is similarly regulated by need state. Here, we used fast-scan cyclic voltammetry to monitor dopamine concentration changes in the NAc core of rats during a Pavlovian-to-instrumental transfer task in which the motivating influence of two cues, each signaling a distinct food reward (sucrose or food pellets), over an action earning a third unique food reward (polycose) was assessed in a state of hunger and of satiety. Both cues elicited a robust NAc dopamine response when hungry. The magnitude of the sucrose cue-evoked dopamine response correlated with the Pavlovian-to-instrumental transfer effect that was selectively induced by this stimulus. Satiety attenuated these cue-evoked dopamine responses and behavioral responding, even though rats had never experienced the specific food rewards in this state. These data demonstrate that cue-evoked NAc core responses are sensitive to current need state, one critical variable that determines the current adaptive utility of cue-motivated behavior. Food-predictive stimuli motivate food-seeking behavior. Here, we show that food cues evoke a robust nucleus accumbens core dopamine response when hungry that correlates with the cue's ability to invigorate general food seeking. This response is attenuated when sated, demonstrating that food cue-evoked accumbens dopamine responses are sensitive to the need state information that determines the current adaptive utility of cue-motivated action.

Neuroscience of learning and memory for addiction medicine: from habit formation to memory reconsolidation

Identifying effective pharmacological treatments for addictive disorders has remained an elusive goal. Many different classes of drugs have shown some efficacy in preclinical models, but the number of effective clinical therapeutics has remained stubbornly low. The persistence of drug use and the high frequency of relapse is at least partly attributable to the enduring ability of environmental stimuli associated with drug use to maintain behavioral patterns of drug use and induce craving during abstinence. We propose that stimuli associated with drug use exert such powerful control over behavior through the development of abnormally strong memories, and their ability to initiate subconscious sequences of motor actions (habits) that promote uncontrolled drug use. In this chapter, we will review the evidence suggesting that drugs of abuse strengthen associations with cues in the environment and facilitate habit formation. We will also discuss potential mechanisms for disrupting memories associated with drug use to help improve treatments for addiction.

Plain packaging of cigarettes: do we have sufficient evidence?

Tobacco industry marketing is a primary factor influencing cigarette smoking behavior and the cigarette pack has become an important marketing vehicle for tobacco companies. Standardized "plain" cigarette packaging is advocated as a public health policy to prevent and reduce morbidity and mortality caused by smoking by reducing youth smoking initiation and promoting cessation among smokers. Plain packaging was implemented in Australia in December 2012, and several other countries are considering doing so, but each faces foreseeable legal resistance from opponents to such measures. Tobacco companies have challenged these public health policies, citing international trade agreements and intellectual property laws. Decision-making in these court cases will hinge in part on whether the evidence indicates the public health benefits of plain packaging outweigh any potential harm to tobacco manufacturers' interests. We reviewed the available evidence in support of plain packaging, finding evidence from observational, experimental, and population-based studies. Results indicate that plain packaging can reduce positive perceptions of smoking and dissuade tobacco use. Governments deciding to implement plain cigarette packaging measures can rely on this evidence to help make a strong case that plain packaging plays an important role in the context of comprehensive smoking prevention efforts.

Effects of first exposure to plain cigarette packaging on smoking behaviour and attitudes: a randomised controlled study

BACKGROUND

Plain packaging requires tobacco products to be sold in packs with a standard shape, method of opening and colour, leaving the brand name in a standard font and location. We ran a randomised controlled trial to investigate the impact of plain packaging on smoking behaviour and attitudes.

METHODS

In a parallel group randomised trial design, 128 daily smokers smoked cigarettes from their usual UK brand, or a plain Australian brand that was closely matched to their usual UK brand for 24 hours. Primary outcomes were number of cigarettes smoked and volume of smoke inhaled per cigarette. Secondary outcomes were self-reported ratings of motivation to quit, cigarette taste, experience of using the pack, experience of smoking, attributes of the pack, perceptions of the health warning, changes in smoking behaviour, and views on plain packaging.

RESULTS

There was no evidence that pack type had an effect on either of the primary measures (ps > 0.279). However, smokers using plain cigarette packs rated the experience of using the pack more negatively (-0.52, 95% CI -0.82 to -0.22, p = 0.001), rated the pack attributes more negatively (-1.59, 95% CI -1.80 to -1.39, p < 0.001), and rated the health warning as more impactful (+0.51, 95% CI 0.24 to 0.78, p < 0.001).

CONCLUSIONS

Plain cigarette packs reduce ratings of the experience of using the cigarette pack, and ratings of the pack attributes, and increase the self-perceived impact of the health warning, but do not change smoking behaviour, at least in the short term.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN52982308. Registered 27 June 2013.

A hierarchical instrumental decision theory of nicotine dependence

It is important to characterize the learning processes governing tobacco-seeking in order to understand how best to treat this behavior. Most drug learning theories have adopted a Pavlovian framework wherein the conditioned response is the main motivational process. We favor instead a hierarchical instrumental decision account, wherein expectations about the instrumental contingency between voluntary tobacco-seeking and the receipt of nicotine reward determines the probability of executing this behavior. To support this view, we review titration and nicotine discrimination research showing that internal signals for deprivation/satiation modulate expectations about the current incentive value of smoking, thereby modulating the propensity of this behavior. We also review research on cue-reactivity which has shown that external smoking cues modulate expectations about the probability of the tobacco-seeking response being effective, thereby modulating the propensity of this behavior. Economic decision theory is then considered to elucidate how expectations about the value and probability of response-nicotine contingency are integrated to form an overall utility estimate for that option for comparison with qualitatively different, nonsubstitute reinforcers, to determine response selection. As an applied test for this hierarchical instrumental decision framework, we consider how well it accounts for individual liability to smoking uptake and perseveration, pharmacotherapy, cue-extinction therapies, and plain packaging. We conclude that the hierarchical instrumental account is successful in reconciling this broad range of phenomenon precisely because it accepts that multiple diverse sources of internal and external information must be integrated to shape the decision to smoke.