Effects of smoking abstinence on impulsive behavior among smokers high and low in ADHD-like symptoms

The Use of Nonmonetary Outcomes in Health-Related Delay Discounting Research: Review and Recommendations

Delay discounting (DD) refers to the tendency to devalue an outcome as a function of its delay. Most contemporary human DD research uses hypothetical money to assess individual rates of DD. However, nonmonetary outcomes such as food, substances of misuse, and sexual outcomes have been used as well, and have advantages because of their connections to health. This article reviews the literature on the use of nonmonetary outcomes of food, drugs, and sexual outcomes in relation to health and reinforcer pathologies such as substance use disorders, obesity, and sexual risk behaviors, respectively, and makes a case for their use in discounting research. First, food, substances, and sex may be more ecologically valid outcomes than money in terms of their connections to health problems and reinforcer pathologies. Second, consistent trends in commodity-specific (i.e., domain) effects, in which nonmonetary outcomes are discounted more steeply than money, enhance variation in discounting values. Third, commodity-specific changes in discounting with treatments designed to change health choices are described. Finally, methodological trends such as test-retest reliability, magnitude effects, the use of hypothetical versus real outcomes, and age-related effects are discussed in relation to the three outcome types and compared to trends with monetary discounting. Limitations that center around individual preferences, nonsystematic data, and deprivation are discussed. We argue that researchers can enhance their DD research, especially those related to health problems and reinforcer pathologies, with the use of nonmonetary outcomes. Recommendations for future directions of research are delineated.

Relationships Between the Nicotine Metabolite Ratio and Laboratory Assessments of Smoking Reinforcement and Craving Among Adults in a Smoking Cessation Trial

INTRODUCTION

People who metabolize nicotine more quickly are generally less successful at quitting smoking. However, the mechanisms that link individual differences in the nicotine metabolite ratio (NMR), a phenotypic biomarker of the rate of nicotine clearance, to smoking outcomes are unclear. We tested the hypotheses that higher NMR is associated with greater smoking reinforcement, general craving, and cue-induced cigarette craving in a treatment-seeking sample.

METHODS

Participants were 252 adults who smoke cigarettes enrolled in a randomized controlled smoking cessation trial (NCT03262662) conducted in Buffalo, New York, USA. Participants completed the Choice Behavior Under Cued Conditions (CBUCC) paradigm, a laboratory choice procedure, ~1 week before the first cessation treatment visit, at which time a saliva sample was collected for NMR assessment. On each CBUCC trial, participants reported cigarette craving during cue presentation (cigarette, water) and spent $0.01-$0.25 for a chance (5%-95%) to sample the cue (one puff, sip), providing measures of smoking reinforcement (spending for cigarettes vs. water), general cigarette craving (averaged across cigarette and water cues), and cue-specific craving (cigarette craving during cigarette vs. water cues).

RESULTS

As observed in prior work, the NMR was significantly higher among White and female participants. As expected, both spending and cigarette craving were significantly greater on cigarette compared to water trials. However, contrary to our hypotheses, higher NMR was not associated with greater smoking reinforcement, general craving, or cue-specific craving.

CONCLUSIONS

The present data do not support that smoking reinforcement or craving is related to nicotine metabolism among individuals seeking to quit smoking.

IMPLICATIONS

Though greater smoking reinforcement, general craving, and cue-specific craving are hypothesized to be linked to faster nicotine metabolism, there was no evidence of such relationships in the present sample of adults seeking to quit smoking. Further research, including replication and consideration of alternate hypotheses, is warranted to elucidate the mechanisms by which the NMR is related to smoking cessation.

Reward prediction-errors weighted by cue salience produces addictive behaviours in simulations, with asymmetrical learning and steeper delay discounting

Dysfunction in learning and motivational systems are thought to contribute to addictive behaviours. Previous models have suggested that dopaminergic roles in learning and motivation could produce addictive behaviours through pharmacological manipulations that provide excess dopaminergic signalling towards these learning and motivational systems. Redish (2004) suggested a role based on dopaminergic signals of value prediction error, while (Zhang et al., 2009) suggested a role based on dopaminergic signals of motivation. However, both models present significant limitations. They do not explain the reduced sensitivity to drug-related costs/negative consequences, the increased impulsivity generally found in people with a substance use disorder, craving behaviours, and non-pharmacological dependence, all of which are key hallmarks of addictive behaviours. Here, we propose a novel mathematical definition of salience, that combines aspects of dopamine's role in both learning and motivation within the reinforcement learning framework. Using a single parameter regime, we simulated addictive behaviours that the (Zhang et al., 2009; Redish, 2004) models also produce but we went further in simulating the downweighting of drug-related negative prediction-errors, steeper delay discounting of drug rewards, craving behaviours and aspects of behavioural/non-pharmacological addictions. The current salience model builds on our recently proposed conceptual theory that salience modulates internal representation updating and may contribute to addictive behaviours by producing misaligned internal representations (Kalhan et al., 2021). Critically, our current mathematical model of salience argues that the seemingly disparate learning and motivational aspects of dopaminergic functioning may interact through a salience mechanism that modulates internal representation updating.

Effects of short-term nicotine deprivation on delay discounting among young, experienced, exclusive ENDS users: An initial study

Delay discounting describes how rapidly delayed rewards lose value as a function of delay and serves as one measure of impulsive decision-making. Nicotine deprivation among combustible cigarette smokers can increase delay discounting. We aimed to explore changes in discounting following nicotine deprivation among electronic nicotine delivery systems (ENDS) users. Thirty young adults (aged 18-24 years) that exclusively used ENDS participated in two laboratory sessions: one with vaping as usual and another after 16 hr of nicotine deprivation (biochemically assessed). At each session, participants completed a craving measure and three hypothetical delay discounting tasks presenting choices between small, immediate rewards and large, delayed ones (money-money; e-liquid-e-liquid; e-liquid-money). Craving for ENDS significantly increased during short-term nicotine deprivation relative to normal vaping. Delay discounting rates in the e-liquid now versus money later task increased (indicating a shift in preference for smaller, immediate rewards) following short-term nicotine deprivation relative to vaping as usual, but no changes were observed in the other two discounting tasks. Short-term nicotine deprivation increased the preference for smaller amounts of e-liquid delivered immediately over larger, monetary awards available after a delay in this first study of its kind. As similar preference shifts for drug now versus money later have been shown to be indicative of increased desire to use drug as well as relapse risk, the findings support the utility of the current model as a platform to explore interventions that can mitigate these preference shifts. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Prepared and reactive inhibition in smokers and non-smokers

INTRODUCTION

Models of addiction have identified deficits in inhibitory control, or the ability to inhibit inappropriate or unwanted behaviors, as one factor in the development and maintenance of addictive behaviors. Current literature supports disruption of the prefrontal circuits that mediate reactive inhibitory control processes (i.e., inhibition in response to sudden, unplanned changes in environmental demands) in substance use disorders. However, the relationship between disorders of addiction, such as nicotine dependence, and planned inhibitory processes (i.e., inhibition that occurs after advance warning) is unclear. The goal of the present study was to examine the extent to which reactive and planned inhibitory processes are differentially disrupted in nicotine dependent individuals.

METHOD

We employed an internet-based novel stop signal task wherein participants were instructed to stop a continuous movement at either a predictable or unpredictable time. This task explicitly separated planned and reactive inhibitory processes and assessed group differences in task performance between smokers (N = 281) and non-smokers (N = 164). The smoker group was defined as any participant that identified as a smoker and reported an average daily nicotine consumption of at least 2 mg. The non-smoker group was defined as any participant that identified as a non-smoker and had not been a former smoker that quit within the last year. The smoker group also completed a questionnaire regarding smoking behaviors which included the Fägerstrom Test of Nicotine Dependence (FTND). We used these data to assess the continuous relation between planned stopping, unplanned stopping, and smoking behaviors.

RESULTS

We found significant differences in stop times for both reactive and planned stopping between groups as well as within the smoker group. Additionally, in the smoker group, dependence as measured by the FTND was associated with longer stop times on planned stop trials. Surprisingly, greater daily average consumption of nicotine was related to faster stopping for both trial types.

CONCLUSION

These results indicate the relevance of measuring both reactive and planned inhibitory processes for elucidating the relationship between nicotine addiction and mechanisms of inhibitory control.

Not all smokers are alike: the hidden cost of sustained attention during nicotine abstinence

Nicotine Withdrawal Syndrome (NWS)-associated cognitive deficits are notably heterogeneous, suggesting underlying endophenotypic variance. However, parsing this variance in smokers has remained challenging. In this study, we identified smoker subgroups based on response accuracy during a Parametric Flanker Task (PFT) and then characterized distinct neuroimaging endophenotypes using a nicotine state manipulation. Smokers completed the PFT in two fMRI sessions (nicotine sated, abstinent). Based on response accuracy in the stressful, high cognitive demand PFT condition, smokers split into high (HTP, n = 21) and low task performer (LTP, n = 24) subgroups. Behaviorally, HTPs showed greater response accuracy (88.68% ± 5.19 SD) vs. LTPs (51.04% ± 4.72 SD), independent of nicotine state, and greater vulnerability to abstinence-induced errors of omission (EOm, p = 0.01). Neurobiologically, HTPs showed greater BOLD responses in attentional control brain regions, including bilateral insula, dorsal ACC, and frontoparietal Cx for the [correct responses (-) errors of commission] PFT contrast in both states. A whole-brain functional connectivity (FC) analysis with these subgroup-derived regions as seeds identified two circuits: Precentral Cx↔Insula and Insula↔Occipital Cx, with abstinence-induced FC strength increases seen only in HTPs. Finally, abstinence-induced FC and behavior (EOm) differences were positively correlated for HTPs in a Precentral Cx↔Orbitofrontal cortical circuit. In sum, only the HTP subgroup demonstrated sustained attention deficits following 48-hr nicotine abstinence, a stressor in dependent smokers. Unpacking underlying smoker heterogeneity with this 'dual (task and abstinence) stressor' approach revealed discrete smoker subgroups with differential attentional deficits to withdrawal that could be novel pharmacological/behavioral targets for therapeutic interventions to improve cessation outcomes.

Deprivation Has Inconsistent Effects on Delay Discounting: A Review

Delay discounting, the tendency for outcomes to be devalued as they are more temporally remote, has implications as a target for behavioral interventions. Because of these implications, it is important to understand how different states individuals may face, such as deprivation, influence the degree of delay discounting. Both dual systems models and state-trait views of delay discounting assume that deprivation may result in steeper delay discounting. Despite early inconsistencies and mixed results, researchers have sometimes asserted that deprivation increases delay discounting, with few qualifications. The aim of this review was to determine what empirical effect, if any, deprivation has on delay discounting. We considered many kinds of deprivation, such as deprivation from sleep, drugs, and food in humans and non-human animals. For 23 studies, we analyzed the effect of deprivation on delay discounting by computing effect sizes for the difference between delay discounting in a control, or baseline, condition and delay discounting in a deprived state. We discuss these 23 studies and other relevant studies found in our search in a narrative review. Overall, we found mixed effects of deprivation on delay discounting. The effect may depend on what type of deprivation participants faced. Effect sizes for deprivation types ranged from small for sleep deprivation (Hedge's gs between −0.21 and 0.07) to large for opiate deprivation (Hedge's gs between 0.42 and 1.72). We discuss possible reasons why the effect of deprivation on delay discounting may depend on deprivation type, including the use of imagined manipulations and deprivation intensity. The inconsistency in results across studies, even when comparing within the same type of deprivation, indicates that more experiments are needed to reach a consensus on the effects of deprivation on delay discounting. A basic understanding of how states affect delay discounting may inform translational efforts.

Association between nicotine dependency with occupational injury in Korean men

Background

The relationship between smoking status or second-hand smoking and occupational injuries has been the subject of considerable study, but few have studied the relationship between nicotine dependence and occupational injuries. The objective of this study was to investigate the relationship between nicotine dependence and occupational injury among employees at a range of Korean companies.

Methods

Initially, the personal and occupational characteristics and nicotine dependences of workers were measured, and 12 months later a survey was used to determine whether subjects had experienced any occupational injury. This study was conducted in several workplaces on 6,893 male workers in manufacturing and service industries that received health screening at Inha University Hospital in Incheon.

Results

The adjusted odds ratios (ORs) of occupational injury in the low, moderate, and high nicotine dependence groups were 1.38 (95% confidence interval [CI]: 1.04-1.84), 1.52 (95% CI: 1.10-2.10), and 1.71 (95% CI: 0.92-3.19), respectively. For smokers only, adjusted ORs tended to increase linearly (p for trend < 0.05). When only smokers were included, analysis of continuous FTND (Fagerstrom Test of Nicotine Dependence) scores showed that adjusted OR increased by 1.10 (95% CI: 1.03-1.19) per FTND point. After stratifying the data by working type and working hours per week, the non-shift work group maintained this relationship (OR: 1.13, 95% CI: 1.04-1.24) and OR was higher in the group that works more than 60 hours per week with FTND score as a continuous variable (OR: 1.24, 95% CI: 1.07-1.44).

Conclusions

The study shows nicotine dependency might affect occupational injury. From a short-term perspective, addressing worker's nicotine dependence by giving an adequate break time or smoking area might reduce work-related injuries.

Inhibitory Performance in Smokers Relative to Nonsmokers When Exposed to Neutral, Smoking- and Money-Related Pictures

INTRODUCTION

Smoking is associated with significant negative health consequences. It has been suggested that deficient inhibitory control may be implicated in (nicotine) addiction, but its exact role has not yet been elucidated. In the current study, our aim was to investigate the role of inhibitory control in relation to nicotine addiction in contexts that differ in terms of reward.

METHODS

Participants filled out questionnaires and performed a go/no-go task with three conditions. In one condition, the stimuli were neutral color squares, and in the reward conditions, these were smoking-related pictures and money-related pictures, respectively. In total, 43 non-abstinent individuals that smoke and 35 individuals that do not smoke were included in the sample.

RESULTS

The main results showed that individuals that smoke, relative to individuals that do not smoke, had reduced inhibitory control in both reward contexts, relative to a neutral context. The reductions in inhibitory control were mirrored by speeded responses.

CONCLUSIONS

Individuals that smoke seem to present with reduced inhibitory control, which is most pronounced in contexts of reward. Consistent with incentive sensitization theory, the reduced inhibitory control may be (at least partly) due to the heightened approach bias to reward-related stimuli as indicated by the speeded responses.

Time-Varying Functional Connectivity Decreases as a Function of Acute Nicotine Abstinence

BACKGROUND

The nicotine withdrawal syndrome (NWS) includes affective and cognitive disruptions whose incidence and severity vary across time during acute abstinence. However, most network-level neuroimaging uses static measures of resting-state functional connectivity and assumes time-invariance and is thus unable to capture dynamic brain-behavior relationships. Recent advances in resting-state functional connectivity signal processing allow characterization of time-varying functional connectivity (TVFC), which characterizes network communication between networks that reconfigure over the course of data collection. Therefore, TVFC may more fully describe network dysfunction related to the NWS.

METHODS

To isolate alterations in the frequency and diversity of communication across network boundaries during acute nicotine abstinence, we scanned 25 cigarette smokers in the nicotine-sated and abstinent states and applied a previously validated method to characterize TVFC at a network and a nodal level within the brain.

RESULTS

During abstinence, we found brain-wide decreases in the frequency of interactions between network nodes in different modular communities (i.e., temporal flexibility). In addition, within a subset of the networks examined, the variability of these interactions across community boundaries (i.e., spatiotemporal diversity) also decreased. Finally, within 2 of these networks, the decrease in spatiotemporal diversity was significantly related to NWS clinical symptoms.

CONCLUSIONS

Using multiple measures of TVFC in a within-subjects design, we characterized a novel set of changes in network communication and linked these changes to specific behavioral symptoms of the NWS. These reductions in TVFC provide a meso-scale network description of the relative inflexibility of specific large-scale brain networks during acute abstinence.

Psychopathology, disordered eating, and impulsivity in patients seeking bariatric surgery

BACKGROUND

Most patients who undergo bariatric surgery experience significant weight loss and improvements in obesity-related co-morbidities in the first 6-18 months after surgery. However, 20%-30% of patients experience suboptimal weight loss or significant weight regain within the first few postoperative years. Psychosocial functioning may contribute to suboptimal weight loss and/or postoperative psychosocial distress.

OBJECTIVE

Assess psychosocial functioning, eating behavior, and impulsivity in patients seeking bariatric surgery.

SETTING

Two university hospitals.

METHODS

Validated interviews and questionnaires. Impulsivity assessed via computer program.

RESULTS

The present study included a larger (n = 300) and more racially diverse (70% non-White) sample than previous studies of these relationships. Forty-eight percent of participants had a current psychiatric diagnosis and 78% had at least 1 lifetime diagnosis. Anxiety disorders were the most common current diagnosis (25%); major depressive disorder was the most common lifetime diagnosis (44%). Approximately 6% of participants had a current alcohol or substance use disorder; 7% had a positive drug screen before surgery. A current psychiatric diagnosis was associated with greater symptoms of food addiction and night eating. Current diagnosis of alcohol use disorder or a lifetime diagnosis of anxiety disorders was associated with higher delay discounting.

CONCLUSION

The study identified high rates of psychopathology and related symptoms among a large, diverse sample of bariatric surgery candidates. Psychopathology was associated with symptoms of disordered eating and higher rates of delay discounting, suggesting impulse control issues.

No differences in delay discounting between smokers with and without HIV

RATIONALE

People with HIV (PWH) smoke cigarettes at much higher rates than the general population and evidence-based cessation methods are less effective, putting PWH at greater risk for negative health outcomes. It is critical to identify the factors that underlie this health disparity. Delay discounting-the decline in the value of a reward when it is delayed-may explain this disparity.

OBJECTIVES

This study aimed to (1) compare delay discounting between adult smokers with HIV and without HIV and (2) evaluate whether acute smoking abstinence disproportionately increases delay discounting among smokers with HIV.

METHODS

This sub-study was part of a larger study (NCT03169101) examining predictors of smoking cessation outcomes among smokers with HIV (n = 34) and smokers without HIV (n = 46) at two counterbalanced laboratory sessions (once smoking-as-usual and once following 24-h biochemically confirmed abstinence) then again, after 8 weeks of smoking cessation treatment.

RESULTS

There were no significant differences in delay discounting rates between HIV status groups (p = 0.49) or within-subject abstinence effects (p = 0.70). However, smokers without HIV exhibited a significant increase in delay discounting following smoking cessation treatment compared to baseline (p = 0.02), whereas the change among smokers with HIV did not reach statistical significance (p = 0.09).

CONCLUSIONS

These findings do not support differences in delay discounting as a reason for the lower success rates of HIV+ smokers at quitting. Although delay discounting may not explain the disparity in smoking rates between people with and without HIV, future work should focus on additional correlates of higher smoking rates and lower quit rates among people with HIV.

Digital failure: An emerging reason of anger expression among adolescents

Network connectivity can often lead to positive as well as negative mood states among regular Internet users. Recently, studies have mainly focused on the impact of Internet abuse/addiction on the various aspects of the individual, in terms of cognitive, emotional, behavioral, and interpersonal domains. However, one of the issues that is not much reported are the issues about what happens to the children who are not able to access the internet due to connectivity issues. Given this, the current article discusses two cases with negative emotional and behavioral manifestations of increased anger and frustration due to reduced Internet connectivity. This can help draw more research and attention to the need for increased cyber-literacy and incorporation of anger management programs into psychological interventions that address Internet Addiction.

Cognitive rigidity and BDNF-mediated frontostriatal glutamate neuroadaptations during spontaneous nicotine withdrawal

Cognitive flexibility is the ability to switch strategic responses adaptively in changing environments. Cognitive rigidity imposed by neural circuit adaptations during nicotine abstinence may foster maladaptive nicotine taking in addicts. We systematically examined the effects of spontaneous withdrawal in mice exposed to either nicotine (6.3 or 18 mg/kg/day) or saline for 14 days on cognitive flexibility using an operant strategy set-shifting task. Because frontostriatal circuits are critical for cognitive flexibility and brain-derived neurotrophic factor (BDNF) modulates glutamate plasticity in these circuits, we also explored the effects of nicotine withdrawal on these neurochemical substrates. Mice undergoing nicotine withdrawal required more trials to attain strategy-switching criterion. Error analysis show that animals withdrawn from both nicotine doses committed higher perseverative errors, which correlated with measures of anxiety. However, animals treated with the higher nicotine dose also displayed more strategy maintenance errors that remained independent of negative affect. BDNF mRNA expression increased in the medial prefrontal cortex (mPFC) following nicotine withdrawal. Surprisingly, BDNF protein declined in mPFC but was elevated in dorsal striatum (DS). DS BDNF protein positively correlated with perseverative and maintenance errors, suggesting mPFC-DS overflow of BDNF during withdrawal. BDNF-evoked glutamate release and synapsin phosphorylation was attenuated within DS synapses, but enhanced in the nucleus accumbens, suggesting a dichotomous role of BDNF signaling in striatal regions. Taken together, these data suggest that spontaneous nicotine withdrawal impairs distinct components of cognitive set-shifting and these deficits may be linked to BDNF-mediated alterations in glutamate signaling dynamics in discrete frontostriatal circuits.

SmokingOpp: Detecting the Smoking 'Opportunity' Context Using Mobile Sensors

Context plays a key role in impulsive adverse behaviors such as fights, suicide attempts, binge-drinking, and smoking lapse. Several contexts dissuade such behaviors, but some may trigger adverse impulsive behaviors. We define these latter contexts as 'opportunity' contexts, as their passive detection from sensors can be used to deliver context-sensitive interventions. In this paper, we define the general concept of 'opportunity' contexts and apply it to the case of smoking cessation. We operationalize the smoking 'opportunity' context, using self-reported smoking allowance and cigarette availability. We show its clinical utility by establishing its association with smoking occurrences using Granger causality. Next, we mine several informative features from GPS traces, including the novel location context of smoking spots, to develop the SmokingOpp model for automatically detecting the smoking 'opportunity' context. Finally, we train and evaluate the SmokingOpp model using 15 million GPS points and 3,432 self-reports from 90 newly abstinent smokers in a smoking cessation study.

The development and validation of a human screening model of tobacco abstinence

INTRODUCTION

Given the low efficacy of smoking cessation methods, an experimental medicine model indicating smoking abstinence would be of great benefit to the development of new treatments. Hence the sensitivity of cognitive tasks and ambulatory craving measures to smoking abstinence were investigated.

METHODS

Cognitive tasks and ambulatory ratings of craving were assessed for sensitivity to acute abstinence (experiment 1), and nicotine replacement therapy administration (NRT) (experiment 2).

RESULTS

In experiment 1 go/no-go performance was improved (Mean Difference [MD] -0.99, 95% CI: -1.90 to -0.08) and craving was lower (Regression Coefficient [RC] -33.39, 95% CI: -39.96 to -26.82) in satiated compared with abstinent smokers. There was no clear evidence that N-back (MD 0.64, 95% CI: -0.42 to 2.51), delay discounting (MD 0.01, 95% CI: 0.001 to 0.005) or dot probe performance (MD 0.61, 95% CI: -0.87 to 1.54) were sensitive to acute abstinence. In experiment 2 go/no-go performance was improved (MD 1.12, 95% CI: 0.16-2.08) and craving was lower (RC -18.59, 95% CI: -24.63 to -12.55) smokers abstinent overnight receiving NRT compared with placebo. There was no clear evidence that N-back (MD -0.25, 95% CI: -1.45 to 0.94), delay discounting (MD 0.01, 95% CI: -0.002 to 0.004) or dot probe performance (MD -0.49, 95% CI: -1.61 to -0.64) were sensitive to NRT.

CONCLUSIONS

Findings from two experiments converge to suggest that abstinence in smokers reliably increases ambulatory craving assessments and, to a lesser extent, decreases go/no-go task performance. These findings can be utilized in the development of an experimental medicine model to test novel treatments for smoking cessation.

Conscious Abstinence from Smokeless Tobacco Evokes Higher Withdrawal Response and Impairs Cognitive Performance Independent of Sympathetic Response

INTRODUCTION

High consumption of smokeless tobacco in adult Indian population increases the risk of developing oral cancers leading to high morbidity and mortality. Though the influence of abstinence from smoking on cognitive performance has been widely studied, the effect of smokeless tobacco on cognitive performance and its association with withdrawal symptoms is less understood. This study comparatively investigates the effect of short-term conscious abstinence and distraction during abstinence from smokeless tobacco consumption on the craving, withdrawal symptoms, sympathetic response, and cognitive performance in tobacco addicts.

METHODS

Age, sex, education and socioeconomic status matched control (N = 15) and smokeless tobacco addicts (N = 60) were recruited from residential areas in Bhubaneswar for the study. Following randomization of the addicts, conscious abstinence (N = 30) was induced by informed abstinence from tobacco consumption for 8 hours, while distracted cessation (N = 30) was induced by involving the participants in a cognitively engaging task for 8 hours during uninformed tobacco abstinence.

RESULTS

The results of the study show higher withdrawal symptoms and reduced cognitive performance in volunteers with conscious abstinence which was positively correlated. The decreased cognitive performance in conscious cessation was independent of tobacco-induced increase in the LF:HF ratio and cotinine concentration in saliva.

CONCLUSION

While conscious abstinence results in higher withdrawal symptoms, distraction during abstinence lowers these symptoms. Inclusion of distraction sessions during cessation can, therefore, be a new element in tobacco control strategies.

Effects of nicotine and atomoxetine on brain function during response inhibition

The nicotinic acetylcholine receptor (nAChR) agonist nicotine and the noradrenaline transporter inhibitor atomoxetine are widely studied substances due to their propensity to alleviate cognitive deficits in psychiatric and neurological patients and their beneficial effects on some aspects of cognitive functions in healthy individuals. However, despite growing evidence of acetylcholine-noradrenaline interactions, there are only very few direct comparisons of the two substances. Here, we investigated the effects of nicotine and atomoxetine on response inhibition in the stop-signal task and we characterised the neural correlates of these effects using blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) at 3T. Nicotine (7 mg dermal patch) and atomoxetine (60 mg per os) were applied to N = 26 young, healthy adults in a double-blind, placebo-controlled, cross-over, within-subjects design. BOLD images were collected during a stop-signal task that controlled for infrequency of stop trials. There were no drug effects on behavioural performance or subjective state measures. However, there was a pronounced upregulation of activation in bilateral prefrontal and left parietal cortex following nicotine during successful compared to unsuccessful stop trials. The effect of nicotine on BOLD during failed stop trials was correlated across individuals with a measure of trait impulsivity. Atomoxetine, however, had no discernible effects on BOLD. We conclude that nicotine effects on brain function during inhibitory control are most pronounced in individuals with higher levels of impulsivity. This finding is compatible with previous evidence of nicotine effects on stop-signal task performance in highly impulsive individuals and implicates the nAChR in the neural basis of impulsivity.

Cognitive Modeling Suggests That Attentional Failures Drive Longer Stop-Signal Reaction Time Estimates in Attention Deficit/Hyperactivity Disorder

Mean stop-signal reaction time (SSRT) is frequently employed as a measure of response inhibition in cognitive neuroscience research on ADHD. However, this measurement model is limited by two factors which may bias SSRT estimation in this population: 1) excessive skew in "go" RT distributions, and 2) trigger failures, or instances in which individuals fail to trigger an inhibition process in response to the "stop" signal. We use a Bayesian parametric approach, which allows unbiased estimation of the shape of entire SSRT distributions and the probability of trigger failures, to clarify mechanisms of stop-signal task deficits in ADHD. Children with ADHD displayed greater positive skew than their peers in both "go" RT and SSRT distributions. However, they also displayed more frequent trigger failures, which appeared to drive ADHD-related stopping difficulties. Results suggest that stop-signal task performance in ADHD reflects impairments in early attentional processes, rather than inefficiency in the stop process.

A cognitive model-based approach to testing mechanistic explanations for neuropsychological decrements during tobacco abstinence

RATIONALE

Cigarette smokers often experience cognitive decrements during abstinence from tobacco, and these decrements may have clinical relevance in the context of smoking cessation interventions. However, limitations of the behavioral summary statistics used to measure cognitive effects of abstinence, response times (RT) and accuracy rates, may restrict the field's ability to identify robust abstinence effects on task performance and test mechanistic hypotheses about the etiology of these cognitive changes.

OBJECTIVES

The current study explored whether a measurement approach based on mathematical models of cognition, which make the cognitive mechanisms necessary to perform choice RT tasks explicit, would be able to address these limitations.

METHODS

The linear ballistic accumulator model (LBA: Brown and Heathcote, Cogn Psychol 57(3):153-178, 2008) was fit to an existing data set from a study that evaluated the impact of overnight abstinence on flanker task performance.

RESULTS

The model-based analysis provided evidence that smokers' rates of mind wandering increased during abstinence, and was able to index this effect while controlling for participants' strategy changes that were related to the specific experimental paradigm used.

CONCLUSION

Mind wandering is a putative explanation for cognitive withdrawal symptoms during smoking cessation and may be indexed using the LBA. More broadly, the use of formal model-based analyses in future research on this topic has the potential to allow for strong and specific tests of mechanistic explanations for these symptoms.

Alternate versions of a fixed-choice, delay-discounting assessment for repeated-measures designs

Delay discounting, reflected in the tendency to prefer immediate rewards over delayed rewards, is associated with most forms of problematic substance use. When assessed multiple times to examine within-individual changes, for example, following acute drug administration or an intervention, shifts in delay discounting simply because of repeated assessment is a concern, particularly when the assessment task is identical. This may be true for the Monetary Choice Questionnaire (MCQ), a widely used, fixed-item assessment of delay discounting. The present research examined possible within-individual difference/equivalence of MCQ indices at test/retest. This was contrasted with within-individual difference/equivalence when using an alternate version of the MCQ at retest, specifically developed to maintain the assessment structure and scoring of the original MCQ but with different choice items. Eighty-four participants completed delay discounting at test and retest with a 1-week interval; participants were randomized to complete the MCQ at both test and retest (MCQ/MCQ; n = 43) or complete the MCQ at test and an alternate version of the MCQ at retest (MCQ/MCQ-A; n = 41). Conventional hypothesis testing indicated no significant changes in delay discounting in the MCQ/MCQ condition or MCQ/MCQ-A condition. However, equivalence analysis, which is able to established whether scores are statistically equivalent, indicated that test/retest scores were not equivalent in some cases. Specifically, only 1 magnitude in the MCQ/MCQ condition was equivalent at test/retest, whereas 2 magnitudes in the MCQ/MCQ-A condition were equivalent at test/retest. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

The impact of drugs of abuse on executive function: characterizing long-term changes in neural correlates following chronic drug exposure and withdrawal in rats

Addiction has long been characterized by diminished executive function, control, and impulsivity management. In particular, these deficits often manifest themselves as impairments in reversal learning, delay discounting, and response inhibition. Understanding the neurobiological substrates of these behavioral deficits is of paramount importance to our understanding of addiction. Within the cycle of addiction, periods during and after withdrawal represent a particularly difficult point of intervention in that the negative physical symptoms associated with drug removal and drug craving increase the likelihood that the patient will relapse and return to drug use in order to abate these symptoms. Moreover, it is often during this time that drug induced deficits in executive function hinder the ability of the patient to refrain from drug use. Thus, it is necessary to understand the physiological and behavioral changes associated with withdrawal and drug craving-largely manifesting as deficits in executive control-to develop more effective treatment strategies. In this review, we address the long-term impact that drugs of abuse have on the behavioral and neural correlates that give rise to executive control as measured by reversal learning, delay discounting, and stop-signal tasks, focusing particularly on our work using rats as a model system.

ADHD, Smoking Withdrawal, and Inhibitory Control: Results of a Neuroimaging Study with Methylphenidate Challenge

Smoking withdrawal negatively impacts inhibitory control, and these effects are greater for smokers with preexisting attention problems, such as attention deficit/hyperactivity disorder (ADHD). The current study preliminarily evaluated changes in inhibitory control-related behavior and brain activation during smoking withdrawal among smokers with ADHD. Moreover, we investigated the role of catecholamine transmission in these changes by examining the effects of 40 mg methylphenidate (MPH) administration. Adult daily smokers with (n=17) and without (n=20) ADHD completed fMRI scanning under each of three conditions: (a) smoking as usual+placebo; (b) 24 h smoking abstinence+placebo and (c) 24 h smoking abstinence+MPH. Scan order was randomized and counterbalanced. Participants completed a modified Go/No-Go task to assess both sustained and transient inhibitory control. Voxelwise analysis of task-related BOLD signal revealed a significant group-by-abstinence interaction in occipital/parietal cortex during sustained inhibition, with greater abstinence-induced decreases in activation observed among ADHD smokers compared with non-ADHD smokers. Changes in behavioral performance during abstinence were associated with changes in activation in regions of occipital and parietal cortex and bilateral insula during sustained inhibition in both groups. MPH administration improved behavioral performance and increased sustained inhibitory control-related activation for both groups. During transient inhibition, MPH increased prefrontal activation for both groups and increased striatal activation only among ADHD smokers. These preliminary findings suggest that abstinence-induced changes in catecholamine transmission in visual attention areas (eg, occipital and superior parietal cortex) may be associated with inhibitory control deficits and contribute to smoking vulnerability among individuals with ADHD.

Targeting Mediators of Smoking Persistence with Intranasal Insulin

Rapid-acting, non-irritating nasal treatment options for smoking cessation pharmacotherapy are lacking. The halt in development is due, in part, to difficulty in delivering compounds across the blood brain barrier. Recently, in both human and animal models, insulin was shown to be capable of being transported to the cerebrospinal fluid and various brain regions via the “nose-to-brain” pathway, which bypasses the blood brain barrier, but is not free of its own unique, though different from blood brain barrier, challenges. This review will first evaluate and critique pharmacokinetic and pharmacodynamic evidence of intranasal insulin (i.e., nose-to-brain) delivery. As intranasal insulin has been shown in clinical trials to be effective in reducing nicotine cravings, in the remainder of the review, hypothesis-generating literature for additional mediators (i.e., other than the already shown nicotine craving) of smoking persistence will be reviewed. In particular, weight gain, impulsive behavior, and anhedonia have been shown to contribute to the inability to quit smoking. For each of these, after reviewing how the mediator promotes smoking, intranasal insulin literature from animal and clinical models will be critiqued in assessing whether a hypothesis may be generated that intranasal insulin may alleviate it, thereby potentially contributing to a successful smoking cessation outcome.

Where There is Smoke There is Fear-Impaired Contextual Inhibition of Conditioned Fear in Smokers

The odds-ratio of smoking is elevated in populations with neuropsychiatric diseases, in particular in the highly prevalent diagnoses of post-traumatic stress and anxiety disorders. Yet, the association between smoking and a key dimensional phenotype of these disorders-maladaptive deficits in fear learning and fear inhibition-is unclear. We therefore investigated acquisition and memory of fear and fear inhibition in healthy smoking and non-smoking participants (N=349, 22% smokers). We employed a well validated paradigm of context-dependent fear and safety learning (day 1) including a memory retrieval on day 2. During fear learning, a geometrical shape was associated with an aversive electrical stimulation (classical fear conditioning, in danger context) and fear responses were extinguished within another context (extinction learning, in safe context). On day 2, the conditioned stimuli were presented again in both contexts, without any aversive stimulation. Autonomic physiological measurements of skin conductance responses as well as subjective evaluations of fear and expectancy of the aversive stimulation were acquired. We found that impairment of fear inhibition (extinction) in the safe context during learning (day 1) was associated with the amount of pack-years in smokers. During retrieval of fear memories (day 2), smokers showed an impairment of contextual (safety context-related) fear inhibition as compared with non-smokers. These effects were found in physiological as well as subjective measures of fear. We provide initial evidence that smokers as compared with non-smokers show an impairment of fear inhibition. We propose that smokers have a deficit in integrating contextual signs of safety, which is a hallmark of post-traumatic stress and anxiety disorders.

Withdrawal-Related Changes in Delay Discounting Predict Short-Term Smoking Abstinence

INTRODUCTION

Impulsive decision making is associated with smoking behavior and reflects preferences for smaller, immediate rewards and intolerance of temporal delays. Nicotine withdrawal may alter impulsive decision making and time perception. However, little is known about whether withdrawal-related changes in decision making and time perception predict smoking relapse.

METHODS

Forty-five smokers (14 female) completed two laboratory sessions, one following 24-hour abstinence and one smoking-as-usual (order counterbalanced; biochemically verified abstinence). During each visit, participants completed measures of time perception, decision making (ie, discount rates), craving, and withdrawal. Following the second laboratory session, subjects underwent a well-validated model of short-term abstinence (quit week) with small monetary incentives for each day of biochemically confirmed abstinence.

RESULTS

Smokers significantly overestimated time during abstinence, compared to smoking-as-usual (p = .021), but there were no abstinence effects on discount rates (p = .6). During the quit week, subjects were abstinent for 3.5 days (SD = 2.15) and smoked a total of 12.9 cigarettes (SD = 15.8). Importantly, higher discount rates (ie, preferences for immediate rewards) during abstinence (abstinence minus smoking difference score) predicted greater number of days abstinent (p = .01) and fewer cigarettes smoked during the quit week (p = .02). Withdrawal-related change in time reproduction did not predict relapse (p = .2).

CONCLUSIONS

These data suggest that individuals who have a greater preference for immediate rewards during abstinence (vs. smoking-as-usual) may be more successful at maintaining short-term abstinence when provided with frequent (eg, daily) versus less frequent incentive schedules (eg, 1 month). Abstinence-induced changes in decision making may be important for identifying smokers who may benefit from interventions that incentivize abstinence such as contingency management (CM).

IMPLICATIONS

The present results suggest that smokers who place greater subjective value on immediate rewards during withdrawal (compared to smoking-as-usual) may be less likely to relapse if offered small, frequent monetary incentives to maintain abstinence. Thus, the current findings may have important implications for identifying smokers most likely to benefit from particular interventions such as CM. Future research might evaluate whether withdrawal-related changes in delay discounting moderate treatment response to different incentive schedules with the goal of optimizing CM effectiveness to improve abstinence rates.

Does Tobacco Abstinence Decrease Reward Sensitivity? A Human Laboratory Test

INTRODUCTION

Animal studies report abstinence from nicotine makes rewards less rewarding; however, the results of human tests of the effects of cessation on reward sensitivity are mixed. The current study tested reward sensitivity in abstinent smokers using more rigorous methods than most prior studies.

METHODS

A human laboratory study compared outcomes for 1 week prior to quitting to those during 4 weeks postquit. The study used smokers trying to quit, objective and subjective measures, multiple measures during smoking and abstinence, and monetary rewards to increase the prevalence of abstinence. Current daily smokers (n = 211) who were trying to quit completed an operant measure of reward sensitivity and a survey of pleasure from various rewards as well as self-reports of anhedonia, delay discounting, positive affect, and tobacco withdrawal twice each week. A comparison group of long-term former smokers (n = 67) also completed the tasks weekly for 4 weeks. Primary analyses were based on the 61 current smokers who abstained for all 4 weeks.

RESULTS

Stopping smoking decreased self-reported pleasure from rewards but did not decrease reward sensitivity on the operant task. Abstinence also decreased self-reported reward frequency and increased the two anhedonia measures. However, the changes with abstinence were small for all outcomes (6%-14%) and most lasted less than a week.

CONCLUSIONS

Abstinence from tobacco decreased most self-report measures of reward sensitivity; however, it did not change the objective measure. The self-report effects were small.

IMPLICATIONS

Animal research suggests that nicotine withdrawal decreases reward sensitivity. Replication tests of this in humans have produced inconsistent results. We report what we believe is a more rigorous test. We found smoking abstinence slightly decreases self-reports of reward sensitivity but does not do so for a behavioral measure of reward sensitivity.

Nicotine withdrawal-induced inattention is absent in alpha7 nAChR knockout mice

RATIONALE

Smoking is the leading cause of preventable death in the USA, but quit attempts result in withdrawal-induced cognitive dysfunction and predicts relapse. Greater understanding of the neural mechanism(s) underlying these cognitive deficits is required to develop targeted treatments to aid quit attempts.

OBJECTIVES

We examined nicotine withdrawal-induced inattention in mice lacking the α7 nicotinic acetylcholine receptor (nAChR) using the five-choice continuous performance test (5C-CPT).

METHODS

Mice were trained in the 5C-CPT prior to osmotic minipump implantation containing saline or nicotine. Experiment 1 used 40 mg kg-1 day-1 nicotine treatment and tested C57BL/6 mice 4, 28, and 52 h after pump removal. Experiment 2 used 14 and 40 mg kg-1 day-1 nicotine treatment in α7 nAChR knockout (KO) and wildtype (WT) littermates tested 4 h after pump removal. Subsets of WT mice were killed before and after pump removal to assess changes in receptor expression associated with nicotine administration and withdrawal.

RESULTS

Nicotine withdrawal impaired attention in the 5C-CPT, driven by response inhibition and target detection deficits. The overall attentional deficit was absent in α7 nAChR KO mice despite response disinhibition in these mice. Synaptosomal glutamate mGluR5 and dopamine D4 receptor expression were reduced during chronic nicotine but increased during withdrawal, potentially contributing to cognitive deficits.

CONCLUSIONS

The α7 nAChR may underlie nicotine withdrawal-induced deficits in target detection but is not required for response disinhibition deficits. Alterations to the glutamatergic and dopaminergic pathways may also contribute to withdrawal-induced attentional deficits, providing novel targets to alleviate the cognitive symptoms of withdrawal during quit attempts.

Tracking Distraction

OBJECTIVE

Although earlier work has shown a link between mind-wandering and ADHD symptoms, this relationship has not been further investigated by taking into account recent advances in mind-wandering research.

METHOD

The present study provides a comprehensive assessment of the relationship between mind-wandering and ADHD symptomatology in an adult community sample ( N = 105, 71 females, M age = 23.1) using laboratory measures and experience sampling during daily life.

RESULTS

Mind-wandering and detrimental mind-wandering were positively associated with ADHD symptoms. Meta-awareness of mind-wandering mediated the relationship between ADHD symptomatology and detrimental mind-wandering, suggesting that some of the negative consequences can be ameliorated by strategies that facilitate meta-awareness. Interestingly, participants with low ADHD scores showed a positive relationship between detrimental mind-wandering and useful mind-wandering; however, participants with high ADHD scores failed to engage in this type of "strategic" mind-wandering.

CONCLUSION

These results provide new insights into the relationship between ADHD symptomatology and mind-wandering that could have important clinical implications.

Self-control depletion and nicotine deprivation as precipitants of smoking cessation failure: A human laboratory model

OBJECTIVE

The need to understand potential precipitants of smoking relapse is exemplified by relapse rates as high as 95%. The Self-Control Strength model, which proposes that self-control is dependent upon limited resources and susceptible to fatigue, may offer insight into relapse processes. The current study tested the hypothesis that self-control depletion (SCD), produced from engagement in emotional suppression, would serve as a novel antecedent for cessation failure, as indexed by a validated laboratory analogue of smoking lapse and relapse. We also examined whether SCD effects interacted with those of a well-established relapse precipitant (i.e., nicotine deprivation). Craving and behavioral economic indices (delay discounting and demand) were tested as hypothesized mechanisms for increased cessation failure. Ultimately, a moderated mediation model was used to test nicotine deprivation as a hypothesized moderator of SCD effects.

METHOD

We used a 2 × 2 (12-hr deprivation vs. no deprivation; SCD vs. no SCD) factorial between-subjects design (N = 128 smokers).

RESULTS

The primary hypothesis of the study was supported, as SCD increased lapse behavior (p = .04). Nicotine deprivation significantly increased craving, cigarette demand, delay discounting, and lapse behavior. No main effects were found for SCD on putative mediators (i.e., craving, demand, and discounting), but the SCD and deprivation manipulations interacted upon craving (p = .04). The moderated mediation model was significant. SCD was found to increase craving among nicotine deprived smokers, which mediated effects on lapse behavior.

CONCLUSIONS

SCD appears to play an important role in smoking relapse and may be a viable target for intervention. (PsycINFO Database Record

Behavioural tasks sensitive to acute abstinence and predictive of smoking cessation success: a systematic review and meta-analysis

BACKGROUND AND AIMS

Performance on cognitive tasks may be sensitive to acute smoking abstinence and may also predict whether quit attempts fail. Our aim was to conduct a systematic review and meta-analysis to identify cognitive tasks sensitive to acute abstinence and predictive of smoking cessation success.

METHODS

Embase, Medline, PsycInfo and Web of Science were searched up to March 2016. Studies were included if they enrolled adults and assessed smoking using a quantitative measure. Studies were combined in a random effects meta-analysis.

RESULTS

We included 42 acute abstinence studies and 13 cessation studies. There was evidence for an effect of abstinence on delay discounting [d = 0.26, 95% confidence interval (CI) = 0.07-0.45, P = 0.005], response inhibition (d = 0.48, 95% CI = 0.26-0.70, P < 0.001), mental arithmetic (d = 0.38, 95% CI = 0.06-0.70, P = 0.018), and recognition memory (d = 0.46, 95% CI = 0.23-0.70, P < 0.001). In contrast, performance on the Stroop (d = 0 .17, 95% CI = -0.17-0.51, P = 0.333) and smoking Stroop (d = 0.03, 95% CI = -0.11-0.17, P = 0.675) task was not influenced by abstinence. We found only weak evidence for an effect of acute abstinence on dot probe task performance (d = 0.15, 95% CI = -0.01-0.32, P = 0.072). The design of the cessation studies was too heterogeneous to permit meta-analysis.

CONCLUSIONS

Compared with satiated smokers, acutely abstinent smokers display higher delay discounting, lower response inhibition, impaired arithmetic and recognition memory performance. However, reaction-time measures of cognitive bias appear to be unaffected by acute tobacco abstinence. Conclusions about cognitive tasks that predict smoking cessation success were limited by methodological inconsistencies.

Sex differences in the reduction of impulsive choice (delay discounting) for cocaine in rats with atomoxetine and progesterone

RATIONALE

Impulsive choice, or an inability to delay immediate gratification, has been strongly linked to the development and persistence of drug abuse. Indeed, delaying drug use itself may underlie drug addiction and relapse. Thus, employing treatments that are efficacious in reducing impulsive choice (atomoxetine; ATO) or drug-seeking behavior (progesterone; PRO) may be an effective means of treating drug addiction.

OBJECTIVE

The current study assessed sex differences in the effects of PRO, ATO, and their combination in a delay discounting paradigm for cocaine and for sucrose pellets.

METHOD

Male and female rats chose between a small-immediate or a large-delayed (0, 7.5, 15, 30, 60 s) outcome in an impulsive choice procedure for sucrose pellets (1 vs. 3 pellets) or for iv cocaine infusions (0.3 vs. 0.9 mg/kg). Following baseline assessment of impulsive choice, rats received daily treatment of vehicle (VEH), PRO (0.5 mg/kg), ATO (1.5 mg/kg), or a combination (PRO + ATO) until a second assessment of impulsive choice was determined.

RESULTS

Compared to the VEH group, females were less impulsive for cocaine following PRO or the PRO + ATO combined treatment, whereas males were less impulsive for cocaine following ATO. No treatment effects were observed on impulsive choice for sucrose pellets.

CONCLUSIONS

The present results indicate that impulsive choice for cocaine is reduced by PRO in females and by ATO in males. These findings suggest both treatments may be an effective intervention in treating cocaine abuse, but that their effectiveness differs by sex.

Smoke and mirrors: The overnight abstinence paradigm as an index of disrupted cognitive function

RATIONALE

Smoking abstinence is known to cause decrements in cognition, but the effects are small and variable. One way to reduce variance may be to aggregate measures or visits. Although trait-like individual differences in smoking abstinence effects on cognition are theorized to predict relapse, the test-retest reliability (TRR) assumed in trait models has not been evaluated.

OBJECTIVES

The objectives of this study were to assess the value of aggregating measures to determine effect sizes (ESs) of smoking versus abstinence on measures of cognition and to assess the short-term TRR of abstinence effects on cognition.

METHODS

Thirty adult smokers completed the typical overnight abstinence paradigm twice; each visit pair consisted of one smoking visit and one abstinent visit. Measures of attention, working memory, and inhibitory control were obtained in each visit.

RESULTS

There were small to medium ESs for smoking abstinence on individual cognitive measures during the first abstinence experience ("visit pair"). Aggregating the measures within the visit pair and across visit pairs additively increased the ES of smoking versus abstinence. Although TRRs were acceptable between smoking visits and between abstinent visits, TRRs for abstinence effects (smoking vs. abstinent visit differences) on cognition were consistently weak.

DISCUSSION

The ability of the typical overnight abstinence paradigm to reflect disrupted cognition at the group level can be substantially improved by aggregating across cognitive outcomes and/or multiple study visits. However, the patterns of poor TRR of smoking-abstinence differences in cognition caution against their use as trait-like markers in studies of relapse or treatment response.

Cognitive control deficits during mecamylamine-precipitated withdrawal in mice: Possible links to frontostriatal BDNF imbalance

Nicotine is a major psychoactive and addictive component of tobacco. Although cessation of tobacco use produces various somatic and affective symptoms, withdrawal-related cognitive deficits are considered to be a critical symptom that predict relapse. Therefore, delineating the cognitive mechanisms of nicotine withdrawal may likely provide gainful insights into the neurobiology of nicotine addiction. The present study was designed to examine the effects of nicotine withdrawal induced by mecamylamine, a non-specific nicotinic receptor (nAChR) antagonist, on cognitive control processes in mice using an operant strategy switching task. Brain-derived neurotrophic factor (BDNF) modulates synaptic transmission in frontostriatal circuits, and these circuits are critical for executive functions. Thus, we examined the effects of mecamylamine-precipitated nicotine withdrawal on prefrontal and striatal BDNF protein expression. Mice undergoing precipitated nicotine withdrawal required more trials to attain strategy switching criterion as compared to the controls. Error analysis indicated that impaired performance in these animals was mostly related to their inability to execute the new strategy. The striatal/prefrontal BDNF ratios robustly increased following precipitated nicotine withdrawal. Moreover, higher BDNF ratios were associated with longer task acquisition. Collectively, our findings illustrate that mecamylamine-induced nicotine withdrawal disrupts cognitive control processes and that these changes are possibly linked to perturbations in frontostriatal BDNF signaling.

Rapid-response impulsivity: definitions, measurement issues, and clinical implications

Impulsivity is a multifaceted construct that is a core feature of multiple psychiatric conditions and personality disorders. However, progress in understanding and treating impulsivity is limited by a lack of precision and consistency in its definition and assessment. Rapid-response impulsivity (RRI) represents a tendency toward immediate action that occurs with diminished forethought and is out of context with the present demands of the environment. Experts from the International Society for Research on Impulsivity (InSRI) met to discuss and evaluate RRI measures in terms of reliability, sensitivity, and validity, with the goal of helping researchers and clinicians make informed decisions about the use and interpretation of findings from RRI measures. Their recommendations are described in this article. Commonly used clinical and preclinical RRI tasks are described, and considerations are provided to guide task selection. Tasks measuring two conceptually and neurobiologically distinct types of RRI, "refraining from action initiation" (RAI) and "stopping an ongoing action" (SOA) are described. RAI and SOA tasks capture distinct aspects of RRI that may relate to distinct clinical outcomes. The InSRI group recommends that (a) selection of RRI measures should be informed by careful consideration of the strengths, limitations, and practical considerations of the available measures; (b) researchers use both RAI and SOA tasks in RRI studies to allow for direct comparison of RRI types and examination of their associations with clinically relevant measures; and (c) similar considerations be made for human and nonhuman studies in an effort to harmonize and integrate preclinical and clinical research.

Acoustic startle and prepulse inhibition predict smoking lapse in posttraumatic stress disorder

Most smokers who attempt to quit lapse within the first week and are ultimately unsuccessful in their quit attempt. Nicotine withdrawal exacerbates cognitive and attentional problems and may be one factor in smoking relapse. The startle reflex response and prepulse inhibition (PPI) of the response are sensitive to arousal and early attentional dysregulation. The current study examined whether startle response and PPI are related to early smoking lapse, and if this differs in people with and without posttraumatic stress disorder (PTSD). Participants with (N = 34) and without (N = 57) PTSD completed a startle reflex and PPI assessment during (1) ad lib smoking (2) on the first day of abstinence during a quit attempt. Most (88%) participants lapsed within the first week of the quit attempt. PTSD status predicted shorter time to lapse. Larger startle magnitude and greater PPI predicted a longer duration before smoking lapse. When diagnostic groups were examined separately, greater PPI predicted a longer successful quit attempt only in participants with a PTSD diagnosis. The startle reflex response and PPI may provide an objective, neurophysiological evaluation of regulation of arousal and early attentional processes by nicotine, which are important factors in smoking cessation success.

The moderating role of cognitive capacities in the association between social norms and drinking behaviors

BACKGROUND

The literature documents 2 related yet distinct social normative influences on adolescent drinking. Descriptive norms refer to perceptions of how much others engage in a particular behavior, whereas injunctive norms refer to the extent to which others approve of a particular behavior. Theoretical formulations suggest that whether descriptive or injunctive norms guide drinking behavior depends on cognitive factors related to executive functioning. Cognitive capacities, specifically inhibitory control (IC) and preplanning, were tested as moderators of the association between social norms and alcohol use using a longitudinal design and community sample of adolescents.

METHODS

This longitudinal study included 387 adolescents and 3 annual waves of data. Behavioral tasks assessed IC (Stop Signal Task) and preplanning (Tower of London) and social norms and drinking were assessed using self-report measures.

RESULTS

Significant interactions were found for descriptive and injunctive norms with preplanning and descriptive norms with IC. As hypothesized, descriptive norms were stronger prospective predictors of alcohol use at low levels of cognitive preplanning, whereas injunctive norms were stronger prospective predictors at high levels of cognitive preplanning. Descriptive norms prospectively predicted alcohol use at high, but not at low levels of IC.

CONCLUSIONS

These findings highlight the complexity of normative influences and suggest that descriptive and injunctive norms have differential effects on future drinking for individuals with different cognitive capacities.

Time dependency of craving and response inhibition during nicotine abstinence

BACKGROUND

Nicotine withdrawal produces increased craving for cigarettes and deficits in response inhibition, and these withdrawal symptoms are predictive of relapse. Although it is well-established that these symptoms emerge early during abstinence, there is mixed evidence regarding whether they occur simultaneously. Given the importance of the early withdrawal period, this study examined craving and response inhibition at 24h and 72h abstinence.

METHODS

Twenty-one non-treatment seeking adult smokers were evaluated at baseline, 24h, and 72h abstinence for craving (Questionnaire on Smoking Urges - Brief) and response inhibition (Stop Signal Task, Stroop Task, Continuous Performance Task). Generalized linear regression models were used for primary outcomes, and Pearson correlations for examining the association between craving and response inhibition.

RESULTS

Factor 2 craving (anticipated relief of negative affect) increased from baseline to 24h abstinent (p=0.004), which subsided by 72h (p=0.08). Deficits in response inhibition measured by the Stop Signal Task were observed at 72h (p=0.046), but not 24h (p=0.318). No correlation was found between response inhibition and craving at any time point (p-values>0.19), except between the Stroop Task and factor 1 craving at baseline (p=0.025).

CONCLUSIONS

Factor 2 craving peaked at 24h, whereas deficits in response inhibition did not emerge until 72h, indicating that need to target craving and cognitive function during early abstinence may not occur simultaneously. Further characterizing the time course of withdrawal symptoms may guide development of targeted treatments for smoking cessation.

Smoking abstinence and neurocognition: implications for cessation and relapse

In this chapter, we review the last decade of research on the effects of smoking abstinence on various forms of neurocognition, including executive function (working memory, sustained attention, response inhibition), reward processing, and cue-reactivity. In our review we identify smoking abstinence-induced deficits in executive function mediated by effects on frontal circuitry, which in turn is known to be affected by modulation of cholinergic, dopaminergic, and other neurotransmitter systems. We also review evidence that smoking abstinence blunts reactivity to non-drug reinforcers-a finding that is consistent with results in the animal literature. Finally, our review of cue-reactivity indicates that smoking abstinence does not appear to amplify cue-provoked craving, although it may increase attentional bias to smoking-related cues. Inconsistencies across findings and potential contributing factors are discussed. In addition, we review the literature on the effects of nicotine and non-nicotine factors in neurocognition. Finally, we provide a multi-factor model and an agenda for future research on the effects of smoking abstinence on neurocognition. The model includes four distinct yet interacting factors, including: Negative Reinforcement, Drug-Reward Bias, Goal and Skill Interference, and Non-Cognitive Factors. Additional research is needed to further evaluate the scope and time-course of abstinence-induced changes in neurocognition, the mechanisms that underlie these changes and the specific role of these processes in drug reinforcement, lapse, and relapse.

Greater sensitivity to novelty in rats is associated with increased motor impulsivity following repeated exposure to a stimulating environment: implications for the etiology of impulse control deficits

Heightened motor impulsivity and increased novelty-seeking commonly co-occur in psychiatric disorders, including drug addiction. However, the relationship between these two phenomena remains unclear. One-time tests of novelty sensitivity commonly used in preclinical experiments, such as the open-field or novel-object test, fail to capture the fact that novelty-seekers repeatedly experience novel, stimulating situations. The present study therefore investigated whether repeated exposure to a novel, stimulating environment (SE) altered impulsive action. Male Long-Evans rats were trained to perform the five-choice serial reaction time task (5CSRTT) which measures motor impulsivity in the form of premature responding as well as attention and motivation. Animals were then exposed to a novel SE (1 h/day for 16 days) immediately prior to the 5CSRTT. Significant increases in premature responding were observed in a subgroup of reactive animals termed high responders (HR-SE). These rats were not more impulsive at baseline, and levels of impulsivity normalised once exposure to the SE was discontinued. No other aspect of 5CSRTT performance was affected by the SE challenge. We also determined that HR-SE rats were hyperactive in a novel environment. Biochemical analyses revealed changes in gene and protein expression within the dorsal hippocampus of HR-SE rats, including decreases in mRNA encoding the dopamine D1 receptor and brain-derived neurotrophic factor. These results indicate a novel mechanism by which impulsivity and novelty-reactivity interact that may enhance addiction vulnerability synergistically. Furthermore, studying such context-induced impulsivity may provide insight into the process by which environmental load precipitates psychiatric symptoms in impulse control disorders.

Optimizing treatments for nicotine dependence by increasing cognitive performance during withdrawal

INTRODUCTION

Current FDA-approved smoking cessation pharmacotherapies have limited efficacy and are associated with high rates of relapse. Therefore, there is a clear need to develop novel antismoking medications. Nicotine withdrawal is associated with cognitive impairments that predict smoking relapse. It has been proposed that these cognitive deficits are a hallmark of nicotine withdrawal that could be targeted in order to prevent smoking relapse. Thus, pharmacotherapies that increase cognitive performance during nicotine withdrawal may represent potential smoking cessation agents.

AREAS COVERED

The authors review the clinical literature demonstrating that nicotine withdrawal is associated with deficits in working memory, attention and response inhibition. They then briefly summarize different classes of compounds and strategies to increase cognitive performance during nicotine withdrawal. Particular emphasis has been placed on translational research in order to highlight areas for which there is strong rationale for pilot clinical trials of potential smoking cessation medications.

EXPERT OPINION

There is emerging evidence that supports deficits in cognitive function as a plausible nicotine withdrawal phenotype. The authors furthermore believe that the translational paradigms presented here may represent efficient and valid means for the evaluation of cognitive-enhancing medications as possible treatments for nicotine dependence.

Associations of attention-deficit hyperactivity disorder symptom dimensions with smoking deprivation effects in adult smokers

Identifying relations of attention deficit hyperactivity disorder (ADHD) symptom dimensions to individual facets of the tobacco withdrawal syndrome could elucidate the mechanisms linking ADHD and regular smoking. This study examined the unique relations of inattention (IN) and hyperactivity-impulsivity (HI) symptom dimensions of ADHD to a variety of tobacco withdrawal symptoms. One hundred thirty-two community-dwelling adult smokers recruited without regard to ADHD status completed a self-report measure of ADHD symptoms experienced over the past 6 months at a baseline visit. At two subsequent experimental sessions (one following overnight tobacco deprivation and one nondeprived; order counterbalanced), participants completed measures of tobacco withdrawal symptoms, mood, and desire to smoke. Preliminary analyses showed that higher levels of IN and HI symptoms were both associated with higher levels of negative affect and concentration difficulties during nondeprived ("baseline") states (ps < .01). Over and above nondeprived ratings, higher levels of HI symptoms were associated with larger deprivation-induced increases in negative affect, concentration problems, and desire to smoke, particularly for negative affect relief, during deprived states (ps < .01). ADHD symptoms, particularly HI symptoms, are associated with more severe exacerbations in abstinence-induced withdrawal symptoms, which could be an important mechanism of ADHD-smoking comorbidity. These findings suggest the need for clinical studies examining the role of these unique and potentially more severe withdrawal profiles experienced by smokers with high-levels of ADHD symptoms in smoking reinstatement and cessation outcomes.

Trait differences in response to chronic nicotine and nicotine withdrawal in rats

INTRODUCTION

Understanding an individual's vulnerability to drug addiction has important implications for the development of effective personal treatment plans. Although theories acknowledge impulsive behaviour as a key component of drug addiction, little is known about the influence of trait impulsivity on an individual's susceptibility to the effects of psychostimulants on impulsivity at critical phases of the addiction cycle.

METHODS

This study investigated the short and longer-term effects of chronic nicotine administration on impulsive choice in rats selected for high (HI) and low impulsivity (LI) on a delay discounting task. Rats prepared with subcutaneously osmotic mini-pumps received either nicotine (3.16 mg/kg/day [freebase]) or saline for 7 days. Performance was assessed during chronic treatment, early and late withdrawal, and in response to acute nicotine challenges following prolonged abstinence.

RESULTS

Chronic nicotine increased impulsive choice in LI but not HI animals. Spontaneous withdrawal was associated with a nicotine abstinence syndrome, the early stages of which were characterised by opposing effects on impulsive choice in HI and LI animals. A transient decrease in impulsivity was observed in HI animals whilst the LI group remained more impulsive for up to 1 week following drug termination. Following normalisation of behaviour, acute nicotine challenges (0.125, 0.25, 0.5 mg/kg, SC) markedly increased impulsive choice regardless of trait impulsivity and drug history.

CONCLUSION

The results indicate that only LI individuals are vulnerable to chronic drug- and withdrawal-induced impairments in self-control which may increase the likelihood of the transition to, and maintenance of, nicotine dependence.

Association of abstinence-induced alterations in working memory function and COMT genotype in smokers

RATIONALE

The common methionine (met) for valine (val) at codon 158 (val(158)met) polymorphism in the catechol-O-methyltransferase (COMT) gene has been associated with nicotine dependence, alterations in executive cognitive function, and abstinence-induced working memory deficits in smokers.

OBJECTIVES

We sought to replicate the association of the COMT val allele with abstinence-induced alterations in working memory-related activity in task-positive (executive control) and task-negative (default mode network) regions.

METHODS

Forty smokers (20 val/val and 20 met/met) performed an N-back task while undergoing blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) on two separate occasions: following 72 h of confirmed abstinence and during smoking as usual. An independent sample of 48 smokers who completed the identical N-back task during fMRI in smoking vs. abstinence for another study was used as a validation sample.

RESULTS

Contrary to expectations, genotype by session interactions on BOLD signal in executive control regions (dorsolateral prefrontal cortex and dorsal cingulate/medial prefrontal cortex) revealed significant abstinence-induced reductions in the met/met group, but not the val/val group. Results also revealed that val/val smokers may exhibit less suppression of activation in task-negative regions such as the posterior cingulate cortex during abstinence (vs. smoking). These patterns were confirmed in the validation sample and in the whole-brain analysis, though the regions differed from the a priori regions of interest (ROIs) (e.g., precuneus, insula).

CONCLUSIONS

The COMT val(158)met polymorphism was associated with abstinence-related working memory deficits in two independent samples of smokers. However, inconsistencies compared to prior findings and across methods (ROI vs. whole-brain analysis) highlight the challenges inherent in reproducing results of imaging genetic studies in addiction.

Effects of smoking on the acoustic startle response and prepulse inhibition in smokers with and without posttraumatic stress disorder

RATIONALE

Cigarette smokers smoke in part because nicotine helps regulate attention. Prepulse inhibition (PPI) of the startle reflex is a measure of early attentional gating that is reduced in abstinent smokers and in groups with attention regulation difficulties. Attention difficulties are found in people with posttraumatic stress disorder (PTSD).

OBJECTIVES

The aim of this study is to assess whether smoking and abstinence differentially affect the startle response and PPI in smokers with and without PTSD.

METHODS

Startle response and PPI (prepulses at 60, 120, or 240 ms) were measured in smokers with (N = 39) and without (N = 61) PTSD, while smoking and again while abstinent.

RESULTS

Participants with PTSD produced both larger magnitude and faster latency startle responses than controls. Across groups, PPI was greater when smoking than when abstinent. The PTSD and control group exhibited different patterns of PPI across prepulse intervals when smoking and when abstinent. Older age was associated with reduced PPI, but only when abstinent from smoking.

CONCLUSIONS

The effects of PTSD on startle magnitude and of smoking on PPI replicate earlier studies. The different pattern of PPI exhibited in PTSD and control groups across prepulse intervals, while smoking and abstinent suggests that previous research on smoking and PPI has been limited by not including longer prepulse intervals, and that nicotine may affect the time course as well as increasing the level of PPI. The reduced PPI among older participants during abstinence suggests that nicotine may play a role in maintaining attention in older smokers, which may motivate continued smoking in older individuals.

The behavioral- and neuro-economic process of temporal discounting: A candidate behavioral marker of addiction

Addiction science would benefit from the identification of a behavioral marker. A behavioral marker could reflect the projected clinical course of the disorder, function as a surrogate measure of clinical outcome, and/or may be related to biological components that underlie the disorder. In this paper we review relevant literature, made possible with the early and sustained support by NIDA, to determine whether temporal discounting, a neurobehavioral process derived from behavioral economics and further explored through neuroeconomics, may function as a behavioral marker. Our review suggests that temporal discounting 1) identifies individuals who are drug-dependent, 2) identifies those at risk of developing drug dependence, 3) acts as a gauge of addiction severity, 4) correlates with all stages of addiction development, 5) changes with effective treatment, and 6) may be related to the biological and genetic processes that underlie addiction. Thus, initial evidence supports temporal discounting as a candidate behavioral marker. Additional studies will be required in several areas for a more conclusive determination. Confirmation that temporal discounting functions as a behavioral marker for addiction could lead to 1) a screen for new treatments, 2) personalization of prevention and treatment interventions, and 3) the extension of temporal discounting as a behavioral marker for other etiologically similar disorders. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

The countermanding task revisited: fast stimulus detection is a key determinant of psychophysical performance

The countermanding task is a standard method for assessing cognitive/inhibitory control over action and for investigating its neural correlates. In it, the subject plans a movement and either executes it, if no further instruction is given, or attempts to prevent it, if a stop signal is shown. Through various experimental manipulations, many studies have sought to characterize the inhibitory mechanisms thought to be at work in the task, typically using an inferred, model-dependent metric called the stop-signal reaction time. This approach has consistently overlooked the impact of perceptual evaluation on performance. Through analytical work and computer simulations, here we show that psychophysical performance in the task can be easily understood as the result of an ongoing motor plan that is modified (decelerated) by the outcome of a rapid sensory detection process. Notably, no specific assumptions about hypothetical inhibitory mechanisms are needed. This modeling framework achieves four things: (1) it replicates and reconciles behavioral results in numerous variants of the countermanding task; (2) it provides a new, objective metric for characterizing task performance that is more effective than the stop-signal reaction time; (3) it shows that the time window over which detection of a high-visibility stimulus effectively occurs is extremely short (∼20 ms); and (4) it indicates that modulating neuronal latencies and the buildup rates of developing motor plans are two key neural mechanisms for controlling action. The results suggest that manipulations of the countermanding task often cause changes in perceptual detection processes, and not necessarily in inhibition.