Measuring impulsivity and modeling its association with cigarette smoking

Is impulsivity related to attentional bias in cigarette smokers? An exploration across levels of nicotine dependency and deprivation

Research has largely focused on how attentional bias to smoking-related cues and impulsivity independently influence the development and maintenance of cigarette smoking, with limited exploration of the relationship between these mechanisms. The current experiments systematically assessed relationships between multiple dimensions of impulsivity and attentional bias, at different stages of attention, in smokers varying in nicotine dependency and deprivation. Nonsmokers (NS; n  = 26), light-satiated smokers (LS; n  = 25), heavy-satiated smokers (HS; n  = 23) and heavy 12-hour nicotine-deprived smokers (HD; n  = 30) completed the Barratt Impulsivity Scale, delayed discounting task, stop-signal task, information sampling task and a visual dot-probe assessing initial orientation (200 ms) and sustained attention (2000 ms) toward smoking-related cues. Sustained attention to smoking-related cues was present in both HS and LS, while initial orientation bias was only evident in HS. HS and LS also had greater levels of trait motor and nonplanning impulsivity and heightened impulsive choice on the delay discounting task compared with NS, while heightened trait attentional impulsivity was only found in HS. In contrast, in HD, nicotine withdrawal was associated with no attentional bias but heightened reflection impulsivity, poorer inhibitory control and significantly lower levels of impulsive choice relative to satiated smokers. Trait and behavioral impulsivity were not related to the extent of attentional bias to smoking-related cues at any stage of attention, level of nicotine dependency or state of deprivation. Findings have both clinical and theoretical implications, highlighting the unique and independent roles impulsivity and attentional bias may play at different stages of the nicotine addiction cycle.

Impaired inhibition after delta-9-tetrahydrocannabinol in women not related to circulating estradiol levels

Cannabis and its main psychoactive constituent, delta-9-tetrahydrocannabinol (THC), impair cognitive processes, including the ability to inhibit inappropriate responses. However, responses to cannabinoid drugs vary widely, and little is known about the factors that influence the risk for adverse effects. One potential source of variation in response to cannabinoids in women is circulating ovarian hormones such as estradiol and progesterone. Whereas there is some evidence that estradiol affects responses to cannabinoids in rodents, little is known about such interactions in humans. Here, we investigate whether variations in estradiol levels across the follicular phase of the menstrual cycle modulate the effect of THC on inhibitory control in healthy women. Healthy female occasional cannabis users (N = 60) received THC (7.5 mg and 15 mg, oral) and placebo during either the early follicular phase, when estradiol levels are low, or the late follicular phase, when estradiol levels are higher. They completed a Go/No Go (GNG) task at the time of peak drug effect. We hypothesized that the effects of THC on GNG performance would be greater when estradiol levels were elevated. As expected, THC impaired GNG task performance: it increased response time and errors of commission/false alarms and decreased accuracy, relative to placebo. However, these impairments were not related to estradiol levels. These results suggest that THC-induced impairments in inhibitory control are not affected by cycle-related fluctuations in estradiol levels.

Optogenetic disruption of the prelimbic cortex alters long-term decision strategy but not valuation on a spatial delay discounting task

Rats demonstrate a preference for smaller, immediate rewards over larger, delayed ones, a phenomenon known as delay-discounting (DD). Behavior arises from the interaction of multiple decision-making systems, and the medial prefrontal cortex (mPFC) has been identified as a central component in the mediation between these decision systems. To investigate the role of the prelimbic (PL) subregion of mPFC on decision strategy interaction, we compared two cohorts of rats (ChR2-opsin-expressing 'Active' and opsin-absent 'Control') on a spatial delay-discounting task while delivering in-vivo light stimulation into PL at the choice point of select trials. By analyzing the overall delay-adjustment along with deliberative and procedural behavioral strategy markers, our study revealed differences in the decision strategies used between the active and control animals despite both groups showing similar valuations. Control animals developed the expected shift from deliberative to procedural decision strategy on this task (indicated by reaching delay-stability, particularly during late-session laps); however, active-virus animals repeatedly over-adjusted around their preferred delay throughout the entire session, suggesting a significant deficit in procedural decision-making on this task. Active animals showed a significant decrease in proportion of vicarious trial and error events (VTE, a behavior correlated with deliberative processes) on delay adjustment laps relative to control animals. This points to a more nuanced role for VTE, not just in executing deliberation, but in shifting from deliberative to procedural processes. This opto-induced change in VTE was especially pronounced for late-session adjustment laps. We found no other session-by-session or lap-by-lap effects, leaving a particular role for PL in the long-term development of procedural strategies on this task.

Environmental uncertainty and the advantage of impulsive choice strategies

Choice impulsivity is characterized by the choice of immediate, smaller reward options over future, larger reward options, and is often thought to be associated with negative life outcomes. However, some environments make future rewards more uncertain, and in these environments impulsive choices can be beneficial. Here we examined the conditions under which impulsive vs. non-impulsive decision strategies would be advantageous. We used Markov Decision Processes (MDPs) to model three common decision-making tasks: Temporal Discounting, Information Sampling, and an Explore-Exploit task. We manipulated environmental variables to create circumstances where future outcomes were relatively uncertain. We then manipulated the discount factor of an MDP agent, which affects the value of immediate versus future rewards, to model impulsive and non-impulsive behavior. This allowed us to examine the performance of impulsive and non-impulsive agents in more or less predictable environments. In Temporal Discounting, we manipulated the transition probability to delayed rewards and found that the agent with the lower discount factor (i.e. the impulsive agent) collected more average reward than the agent with a higher discount factor (the non-impulsive agent) by selecting immediate reward options when the probability of receiving the future reward was low. In the Information Sampling task, we manipulated the amount of information obtained with each sample. When sampling led to small information gains, the impulsive MDP agent collected more average reward than the non-impulsive agent. Third, in the Explore-Exploit task, we manipulated the substitution rate for novel options. When the substitution rate was high, the impulsive agent again performed better than the non-impulsive agent, as it explored the novel options less and instead exploited options with known reward values. The results of these analyses show that impulsivity can be advantageous in environments that are unexpectedly uncertain.

Sex-Dependent Alterations of Regional Homogeneity in Cigarette Smokers

Biological sex may play a large role in cigarette use and cessation outcomes and neuroimaging studies have demonstrated that cigarette smoking is associated with sex-related differences in brain structure and function. However, less is known about sex-specific alterations in spontaneous brain activity in cigarette smokers. In this study, we investigated the sex-related effects of cigarette smoking on local spontaneous brain activity using regional homogeneity (ReHo) based on resting-state fMRI. Fifty-six smokers (24 females) and sixty-three (25 females) healthy non-smoking controls were recruited. Whole-brain voxelwise 2-way analysis of covariance of ReHo was performed to detect brain regions with sex-dependent alterations on the spontaneous brain activity. Compared to non-smokers, smokers exhibited significant ReHo differences in several brain regions, including the right medial orbitofrontal cortex extended to the ventral striatum/amygdala/parahippocampus, left precuneus, and bilateral cerebellum crus. Smoking and sex interaction analysis revealed that male smokers showed significantly lower ReHo in the right ventral striatum, left cerebellum crus1, and left fusiform gyrus compared to male non-smokers, whereas there are no significant differences between female smokers and non-smokers. Furthermore, the ReHo within the left cerebellum crus1 was negatively correlated with craving scores in male smokers but not in female smokers. Such sex-dependent differences in spontaneous brain activity lays a foundation for further understanding the neural pathophysiology of sex-specific effects of nicotine addiction and promoting more effective health management of quitting smoking.

Exposure to nicotine vapor produced by an electronic nicotine delivery system causes short-term increases in impulsive choice in adult male rats

INTRODUCTION

Traditional cigarette use influences cost-benefit decision making by promoting impulsive choice. However, the impact of exposure via electronic nicotine delivery systems on impulsive choice remains unclear. Hence, the present study examined the short- and long-term effects of nicotine vapor on impulsive choice.

METHODS

Twenty-four adult male rats were trained in the delay discounting task, to choose between small, immediate food rewards or large, delayed food rewards. After 24 days of training in the task, rats were exposed to vapor containing either 0, 12, or 24 mg/mL of nicotine, for ten days. To validate inhalation of nicotine vapor, serum cotinine levels were analyzed on exposure days 1, 5, and 10 using enzyme-linked immunosorbent assay (ELISA). Following vapor exposure, rats were retrained in the discounting task until rats displayed stable responding, and the effects of nicotine vapor on choice preference were assessed.

RESULTS

Rats exposed to 12 and 24 mg/mL nicotine vapor displayed higher serum cotinine levels than control rats exposed to 0 mg/mL vapor. There were no differences in impulsive choice between any vapor exposure groups when tested 15 days after exposure, across 6 days of stable responding, suggesting that nicotine vapor does not have long lasting effects on impulsive choice. Interestingly, a subsequent nicotine vapor challenge revealed short-term increases in impulsive choice immediately following a single exposure to 24 mg/mL nicotine vapor, relative to choice preference immediately following exposure to 0 mg/mL vapor.

CONCLUSIONS

These results suggest that exposure to nicotine vapor causes immediate, short-term increases in impulsive choice.

IMPLICATIONS

E-cigarette use is increasing at an alarming rate, particularly among adolescents and young adults. This is concerning given the lack of research into the effects of nicotine vapor exposure on the brain and behavior. The present study describes a viable rodent model of human e-cigarette use and suggest that exposure to nicotine vapor produces short-term increases in impulsive choice.

The scaled target learning model: Revisiting learning in the balloon analogue risk task

The Balloon Analogue Risk Task (BART) is a sequential decision making paradigm that assesses risk-taking behavior. Several computational models have been proposed for the BART that characterize risk-taking propensity. An aspect of task performance that has proven challenging to model is the learning that develops from experiencing wins and losses across trials, which has the potential to provide further insight into risky decision making. We developed the Scaled Target Learning (STL) model for this purpose. STL describes learning as adjustments to an individual's strategy in reaction to outcomes in the task, with the size of adjustments reflecting an individual's sensitivity to wins and losses. STL is shown to be sensitive to the learning elicited by experimental manipulations. In addition, the model matches or bests the performance of three competing models in traditional model comparison tests (e.g., parameter recovery performance, predictive accuracy, sensitivity to risk-taking propensity). Findings are discussed in the context of the learning process involved in the task. By characterizing the extent to which people are willing to adapt their strategies based on past experience, STL is a step toward a complete depiction of the psychological processes underlying sequential risk-taking behavior.

Assessing Impulsivity in Humans and Rodents: Taking the Translational Road

Impulsivity is a multidimensional construct encompassing domains of behavioral inhibition as well as of decision making. It is often adaptive and associated with fast responses, being in that sense physiological. However, abnormal manifestations of impulsive behavior can be observed in contexts of drug abuse and attention-deficit/hyperactivity disorder (ADHD), among others. A number of tools have therefore been devised to assess the different facets of impulsivity in both normal and pathological contexts. In this narrative review, we systematize behavioral and self-reported measures of impulsivity and critically discuss their constructs and limitations, establishing a parallel between assessments in humans and rodents. The first rely on paradigms that are typically designed to assess a specific dimension of impulsivity, within either impulsive action (inability to suppress a prepotent action) or impulsive choice, which implies a decision that weighs the costs and benefits of the options. On the other hand, self-reported measures are performed through questionnaires, allowing assessment of impulsivity dimensions that would be difficult to mimic in an experimental setting (e.g., positive/negative urgency and lack of premeditation) and which are therefore difficult (if not impossible) to measure in rodents.

Using greenspace and nature exposure as an adjunctive treatment for opioid and substance use disorders: Preliminary evidence and potential mechanisms

The demand for opioid medication to effectively treat pain has contributed to the surging opioid crisis, which is a major source of morbidity and mortality in the U.S. More than 100,000 people begin opioid maintenance treatment (OMT) annually, the standard pharmacotherapy for opioid use disorder (OUD). Although OMT is the standard care for OUD, patients often experience or develop a heightened sensitivity to pain (hyperalgesia) as a result of the opioid medication, and also have high rates of stress, affective, and anxiety-related conditions. These conditions are interactive with other behavioral and environmental correlates of opioid and other substance use disorders including impulsive decision-making (e.g., harmful opioid use associated with increased delay discounting), and a lack of alternative (i.e., substance-free) and social reinforcement. Collectively these complex and multifaceted factors constitute significant predictors of lack of adherence to OMT (and other pharmacotherapies) and relapse. There is an urgent need, therefore, to develop novel adjunctive treatments that preserve the benefits of OMT and various pharmacotherapies, and simultaneously diminish continued pain and hyperalgesia, reduce stress and anxiety-related conditions, target relevant behavioral mechanism such as impulsive choice, and also serve to enhance the value of alternative and substance free activities. Here, we discuss evidence that an environmental manipulation - access to greenspace and nature - could serve as a potential adjunctive treatment to standard pharmacotherapies by targeting multiple biological and behavioral mechanisms that standard pharmacotherapies do not address.

Sex-specific effects of cigarette smoking on caudate and amygdala volume and resting-state functional connectivity

Recent studies have demonstrated sex-specific differences in etiology, course and brain dysfunction that are associated with cigarette smoking. However, little is known about sex-specific differences in subcortical structure and function. In this study, structural and resting-state functional magnetic resonance imaging (fMRI) data were collected from 60 cigarette smokers (25 females) and 67 nonsmokers (28 females). The structural MRI was applied to identify deficits in sex-specific subcortical volume. Using resting-state fMRI, sex-related alterations in resting-state functional connectivity (rsFC) were investigated in subcortical nuclei with volume deficits as seed regions. Compared to nonsmokers, male but not female smokers demonstrated a significantly smaller volume in the left caudate, while female but not male smokers showed a smaller volume in the right amygdala. Resting-state FC analysis revealed that male but not female smokers had increased rsFC between the left caudate and the left prefrontal cortex but decreased rsFC within the bilateral caudate and between the right amygdala and right orbitofrontal cortex (OFC). Furthermore, the right amygdala volume was negatively correlated with the impulsivity score in female but not male smokers. The rsFC of the right amygdala-OFC circuit was negatively associated with the craving score in male but not female smokers. These findings indicate that cigarette smoking may have differential effects on the caudate and amygdala volumes as well as rsFC between men and women, contributing to our knowledge of sex-specific effects of nicotine addiction. Such sex-specific differences in subcortical structure and function may provide a methodological framework for the development of sex-specific relapse prevention therapies.

Psychological Constructs Related to Seat Belt Use: A Nationally Representative Survey Study

Seat belt use can significantly reduce fatalities in motor vehicle crashes (Kahane, 2000). Nevertheless, the current U.S. seat belt use rate of 89.6% (Enriquez & Pickrell, 2019) indicates that a relatively small but pervasive portion of the population does not wear seat belts on a full-time basis. Whereas much is known about the demographic predictors of seat belt use, far less is understood about psychological factors that predict individual proclivities toward using or not using a seat belt. In this study, we examined some of these potential psychological predictors. A probability-based web survey was conducted with 6,038 U.S. residents aged 16 or older who reported having driven or ridden in a car in the past year. We measured self-reported seat belt use and 18 psychological constructs and found that delay of gratification, life satisfaction, risk aversion, risk perception, and resistance to peer influence were positively associated with belt use. Impulsivity and social resistance orientation were negatively associated with belt use. Prior research has shown that psychological factors like delay of gratification, risk aversion/perception, and impulsivity predict other health behaviors (e.g., cigarette smoking, sunscreen use); our results extend this literature to seat belts and can aid the development of traffic safety programs targeted at non-users who-due to such factors-may be resistant to more traditional countermeasures such as legislation and enforcement.

The acute and repeated effects of cigarette smoking and smoking-related cues on impulsivity

INTRODUCTION AND AIMS

Impulsivity may be a risk factor that increases vulnerability to nicotine dependence. However, nicotine exposure itself may directly increase impulsivity. This is a secondary analysis of the first study in a controlled laboratory setting, which assessed the effects of nicotine administration (acute and repeated) and exposure to smoking cues on behavioural impulsivity in humans (ClinicalTrials.gov Identifier: NCT01395797).

DESIGN AND METHODS

Twenty-seven smokers completed three tasks to assess behavioural impulsivity (the Immediate Memory Task and the Delayed Memory Task assessing response initiation, and the GoStop Task assessing response inhibition) following: (i) 4 days of cigarette smoking (nicotinised or denicotinised cigarette); (ii) acute cigarette smoking (nicotinised); and (iii) exposure to smoking-related cues.

RESULTS

Four days of nicotinised cigarette smoking (vs. denicotinised) did not significantly increase Immediate Memory Task, Delayed Memory Task and GoStop scores. However, acute cigarette smoking increased GoStop impulsivity, but only following 4 days of smoking nicotinised cigarettes (P < 0.05). Exposure to smoking-related cues had no statistically significant effect on impulsivity.

DISCUSSION AND CONCLUSIONS

Our results suggest that repeated nicotine exposure may sensitise subsequent acute nicotine effects on behavioural impulsivity in heavy smokers.

Comparison of delay discounting of different outcomes in cigarette smokers, smokeless tobacco users, e-cigarette users, and non-tobacco users

Delay discounting is the process by which a commodity loses value as the delay to its receipt increases. Rapid discounting predicts various maladaptive behaviors including tobacco use. Typically, delay discounting of different outcomes has been compared between cigarette smokers and nonsmokers. To better understand the relationship of delay discounting to different modes of tobacco use, we examined the differences in delay discounting of different outcomes between cigarette smokers, smokeless tobacco users, e-cigarette users, and non-tobacco users. In the present study, all participants completed 8 titrating delay-discounting tasks: $100 gain, $500 gain, $500 loss, alcohol, entertainment, food, a temporary health gain, and a temporary cure from a disease. Non-tobacco users discounted most outcomes less than tobacco users overall; however, there were no differences in discounting among the different types of tobacco users. These results suggest that nicotine consumption of any kind is associated with a higher degree of impulsivity compared to non-tobacco users. Adoption of tobacco products that have been perceived as less harmful (e.g., e-cigarettes) is not associated with a baseline difference or decrease in delay discounting if adopted after a history of cigarette use.

Short-Term Fasting Selectively Influences Impulsivity in Healthy Individuals

Previous research has shown that short-term fasting in healthy individuals is associated with changes in risky decision-making. The current experiment was designed to examine the influence of short-term fasting in healthy individuals on four types of impulsivity: reflection impulsivity, risky decision-making, delay aversion, and action inhibition. Participants were tested twice, once when fasted for 20 h, and once when satiated. Participants demonstrated impaired action inhibition when fasted; committing significantly more errors of commission during a food-related Affective Shifting Task. Participants also displayed decreased reflection impulsivity when fasted, opening significantly more boxes during the Information Sampling Task (IST). There were no significant differences in performance between fasted and satiated sessions for risky decision-making or delay aversion. These findings may have implications for understanding eating disorders such as Bulimia Nervosa (BN). Although BN has been characterized as a disorder of poor impulse control, inconsistent findings when comparing individuals with BN and healthy individuals on behavioral measures of impulsivity question this characterization. Since individuals with BN undergo periods of short-term fasting, the inconsistent findings could be due to differences in the levels of satiation of participants. The current results indicate that fasting can selectively influence performance on the IST, a measure of impulsivity previously studied in BN. However, the results from the IST were contrary to the original hypothesis and should be replicated before specific conclusions can be made.

Promoting Healthy Decision-Making via Natural Environment Exposure: Initial Evidence and Future Directions

Research within psychology and other disciplines has shown that exposure to natural environments holds extensive physiological and psychological benefits. Adding to the health and cognitive benefits of natural environments, evidence suggests that exposure to nature also promotes healthy human decision-making. Unhealthy decision-making (e.g., smoking, non-medical prescription opioid misuse) and disorders associated with lack of impulse control [e.g., tobacco use, opioid use disorder (OUD)], contribute to millions of preventable deaths annually (i.e., 6 million people die each year of tobacco-related illness worldwide, deaths from opioids from 2002 to 2017 have more than quadrupled in the United States alone). Impulsive and unhealthy decision-making also contributes to many pressing environmental issues such as climate change. We recently demonstrated a causal link between visual exposure to nature (e.g., forests) and improved self-control (i.e., decreased impulsivity) in a laboratory setting, as well as the extent to which nearby nature and green space exposure improves self-control and health decisions in daily life outside of the experimental laboratory. Determining the benefits of nearby nature for self-controlled decision-making holds theoretical and applied implications for the design of our surrounding environments. In this article, we synergize the overarching results of recent research endeavors in three domains including the effects of nature exposure on (1) general health-related decision-making, (2) health and decision-making relevant for application to addiction related processes (e.g., OUD), and (3) environmentally relevant decision-making. We also discuss key future directions and conclusions.

Delay discounting and risky choice: Meta-analytic evidence regarding single-process theories

Preferences about delayed rewards and preferences about risk are central to the literature on decision making. Several proposals suggest that such preferences arise from a single process and thus predict strong associations between preferences about delay and risk. Although there is a wealth of data on this association, the evidence is inconclusive; some studies have reported significant associations but many have not. Consequently, it is unclear whether the association between delay preferences and risk preferences is strong enough to support single-process theories. To further explore this question, we took a meta-analytic approach surveying 26 studies totaling 32 effect sizes. Results reveal a small to moderate association between risk preferences and delay preferences. This result provides little support for existing proposals because the observed relationship is no stronger than associations observed between either delay preferences or risk preferences and other variables. Moderating variables provide some explanation for inconsistencies across studies. Implications, including the apparent discrepancy between this literature and the conventional construct of impulsivity, are also discussed.

Effects of repetitive transcranial magnetic stimulation on nicotine consumption and craving: A systematic review

We performed a systematic review of the studies employing repetitive transcranial magnetic stimulation (rTMS) in subjects with smoking addiction. High-frequency (HF) rTMS over the prefrontal cortex (PFC), in particular the left dorsolateral PFC (DLPFC), might represent a save and innovative treatment tool for tobacco consumption and craving in nicotine-dependent otherwise healthy people. rTMS can be effective for this indication also in patients with schizophrenia, but the results are conflicting and sufficient evidence from large-scale trials is still lacking. Promising results have been obtained using particular techniques for brain stimulation, such as deep rTMS and theta burst stimulation. Multiple-target HF rTMS can also have a potential in smoking cessation. fMRI and EEG recordings have proven to be useful for objectively assessing the treatment effects. TMS is likely to be most effective when paired with an evidence-based self-help intervention, cognitive-behavioral interventions and nicotine replacement therapy. However, the most recent studies employed different protocols and yielded heterogeneous results, which should be replicated in further controlled studies with larger sample sizes and rigorous standards of randomization. To date, no recommendation other than that a possible efficacy of HF-rTMS of the left DLPFC can be made for alternative rTMS procedures in nicotine craving and consumption.

A fractionated analysis of hot and cool self-regulation in cigarette smokers from different socioeconomic backgrounds

Smoking cigarettes and low socioeconomic status (SES) are both related to impaired cognition. However, it is unknown whether people of lower SES, who comprise most tobacco smokers worldwide, are more susceptible to cognitive impairment associated with smoking. In this non-randomized, cross-sectional study we investigated the effects of cigarette smoking, SES and their interaction on dissociable executive or “cool” and “hot” measures of behavioural self-regulation. Participants (n = 80) were selected among young physically and mentally healthy smokers and non-smokers who had graduated high school and were from different SES backgrounds. Cool self-regulation was measured by executive function tasks that tap inhibition, updating, shifting, dual tasking, planning, access to long-term memory (semantic fluency), and working memory capacity. Hot measures assessed self-reported impulsivity, delay discounting and risk taking. Exposure to tobacco (cotinine, exhaled carbon monoxide, tobacco dependence, cigarette consumption) was assessed to determine to what extent it mediated the cognitive effects of smoking. Nicotine abstinence and its acute effects were controlled, as were sex, age, schooling, and psychiatric symptoms despite the fact that smokers and non-smokers were selected as being as similar as possible in these demographic characteristics. Lower SES (less years of parental schooling) was associated with worse performance on tasks that measured all cool domains except dual tasking and fluency, while smoking status was related to impaired delayed discounting and impulsivity (hot domains), effects that were not mediated by tobacco exposure. Smoking and SES, however, did not interact. In short, impaired performance in measures of most cool skills was associated with SES irrespective of smoking status; in contrast, regardless of SES, smokers showed specific impairment in hot self-regulation domains (more difficulty resisting immediate temptations and weighing future consequences of actions). Possible explanations for the lack of mediation of tobacco exposure on hot skills of smokers are discussed.

Adolescent morphine exposure induces immediate and long-term increases in impulsive behavior

RATIONALE

Adolescence in humans represents a unique and critical developmental time point associated with increased risk-taking behavior. Converging clinical and epidemiological studies report a peak of drug use during adolescence, leading to the hypothesis that the developing adolescents brain is at risk to lose control over drug intake. Both adolescence and drug abuse are associated with significant cognitive and psychological changes such as lack of impulse control. A simple definition for impulsive behavior is the tendency to act prematurely without foresight. Increase in impulsivity is evident in acute morphine consumption, but to date, little is known with respect to subchronic morphine administration in impulsive behavior, particularly comparing time-dependent effects in adults, young adults, and adolescents.

METHODS

To evaluate this, adult, young adult, and adolescent rats were treated with a subchronic regimen of morphine or saline during 5 days (s.c.). Thereafter, we examined impulsive behavioral effects of morphine administration, 24 h and 25 days after administration in rats, while responding under a five-choice serial reaction time task (5-CSRTT).

RESULTS

Subchronic morphine administration increased premature responding 24 h after the last injection of morphine in adult, young adult, and adolescent rats without increasing motor activity but a significant change in motivation in adult and young adult rats only. After 25 days of abstinence, premature responses were significantly increased in comparison with baseline in adolescent rats but not in adults and young adults.

CONCLUSION

The main conclusion of this study is that morphine exposure in adolescents has a long-term profound effect on motor impulsive behavior later in adulthood. An implication of our findings might be that we should be especially careful about consuming and prescribing opioid drugs in adolescents.

Momentary assessment of impulsive choice and impulsive action: Reliability, stability, and correlates

Impulsivity is associated with substance use, including tobacco use. The degree to which impulsivity fluctuates over time within persons, and the degree to which such intra-individual changes can be measured reliably and validly in ambulatory assessments is not known, however. The current study evaluated two novel ambulatory measures of impulsive choice and impulsive action. Impulsive choice was measured with an eight-item delay discounting task designed to estimate the subjective value of delayed monetary rewards. Impulsive action was measured with a two-minute performance test to assess behavioral disinhibition (the inability to inhibit a motor response when signaled that such a response will not be rewarded). Valid data on impulsive choice were collected at 70% of scheduled reports and valid data on impulsive action were collected on 55% of scheduled reports, on average. Impulsive choice and action data were not normally distributed, but models of relations of these measures with within- and between-person covariates were robust across distributional assumptions. Intra-class correlations were substantial for both impulsive choice and action measures. Between persons, random intercepts in impulsive choice and action were significantly related to laboratory levels of their respective facets of impulsivity, but not self-reported or other facets of impulsivity. Validity of the ambulatory measures is supported by associations between abstinence from smoking and increased impulsivity, but challenged by an association between strong temptations to smoke and reduced impulsive choice. Results suggest that meaningful variance in impulsive choice and action can be captured using ambulatory methods, but that additional measure refinement is needed.

Early onset tobacco cigarette smokers exhibit deficits in response inhibition and sustained attention

BACKGROUND

Initiation of cigarette smoking during adolescence coincides with structural and cognitive neuromaturation. Thus, early onset smokers (EOS; initiated <16 years old) may be at unique risk of altered development of executive function relative to late onset smokers (LOS; initiated >16 years old). This study quantified the effects of age of smoking onset on response impulsivity and inhibitory control using a novel smoking Go/NoGo task (Luijten et al., 2011).

METHODS

Nicotine deprived adult EOS (n = 10) and LOS (n = 10) and adult healthy non-smokers (HNS; n = 10) were shown smoking-related and neutral images with either a blue (Go) or yellow (NoGo) frame. Participants were instructed to respond to blue-framed Go trials quickly and accurately, and withhold responding for yellow-framed NoGo trials.

RESULTS

EOS made more Go response accuracy errors (p ≤ 0.02) and failed more frequently to inhibit responses to NoGo trials (p < 0.02) than LOS and HNS. EOS also made more errors in inhibiting responses to smoking-related (p ≤ 0.02) and neutral (p ≤ 0.02) NoGo trials. EOS reported greater baseline craving for cigarette smoking than LOS (p < 0.04), and craving was significantly associated with greater omission errors (p ≤ 0.04).

CONCLUSIONS

EOS exhibited greater difficulty than LOS in responding accurately to Go stimuli and withholding responses to both smoking and neutral NoGo stimuli, indicating greater response impulsivity, poor attention, and deficits in response inhibition. These findings suggest that EO smoking, in particular, contributes to diminished task-related attention and inhibitory control behaviors in adulthood and provide support for the tobacco-induced neurotoxicity of adolescent cognitive development (TINACD) theory (DeBry and Tiffany, 2008).

Drinking status but not acute alcohol consumption influences delay discounting

OBJECTIVE

The aim of this study was to investigate the following: (a) the effects of acute alcohol on delay discounting; (b) the effects of drinking status on delayed discounting; and (c) whether these effects differ according to reward type (alcohol vs. money).

METHODS

Heavy and light social alcohol users (n = 96) were randomized to receive either an acute dose of alcohol at 0.4 or 0.6 g/kg or placebo in a between-subjects, double-blind design. Delay discounting of alcohol and monetary rewards was measured using a hyperbolic model, with higher scores indicative of greater delay discounting.

RESULTS

ANOVA of discount scores indicated a main effect of reward type, where all participants had higher discount scores for alcohol versus money rewards. A main effect of drinking status was also observed, where heavier drinkers had higher discount scores compared with lighter drinkers. We did not observe a main effect of acute alcohol use on delay discounting or the hypothesized interactions between acute alcohol use and drinking status with reward type.

CONCLUSIONS

Our data suggest that heavier drinkers discount the value of delayed rewards more steeply than lighter drinkers. Delay discounting may therefore be a promising marker of heavy alcohol consumption in social drinkers.

Smoking addiction: the shift from head to hands: Approach bias towards smoking-related cues in low-dependent versus dependent smokers

The dual process theory is central to several models of addiction, implying both an increase of stimulus salience and deficits in inhibitory control. Our major aim is to provide behavioral evidence for an approach bias tendency in smokers and more specifically during smoking cue exposure. The second aim is to examine whether this bias differs in low-dependent versus dependent smokers. Thirty-two smokers (17 low dependent and 15 dependent; cut-off FTND of 4) and 28 non-smokers performed a modified Go/NoGo task using tobacco-related words and neutral words as stimuli. Smokers generally made more mistakes and tended to be faster for smoking-related cues specifically. Low dependents acknowledged more their dependency in declarative questionnaires while making more errors and being slower specifically on smoking cues; dependent smokers were less prone to indicate their addiction, but were faster and accurate when it came to picking the smoking cues. These results suggest that a shift has operated from a mental preoccupation with smoking in the low-dependent group, to smoking as a motor habit in our dependent group. This finding invites experts to rethink smoking addiction in the light of this crucial moment, namely, the shift "from head to hands".

Differences in Delay, but not Probability Discounting, in Current Smokers, E-cigarette Users, and Never Smokers

Steeper delay discounting in substance abuse populations, compared to non-abusing populations, has been well-established in prior studies. Despite the growing interest in e-cigarettes as a novel and relatively understudied form of nicotine consumption, relatively little is known as to how e-cigarette users discount rewards compared to traditional cigarette smokers and never smokers. In the present study, we measured delay and probability discounting rates, as well as perceived risk inherent to a delayed reward, in current traditional cigarette smokers, e-cigarette users, and never smokers. We found that traditional cigarette smokers and e-cigarette users discounted delayed rewards at a similar rate—and both were steeper than never smokers. However, no differences were observed in probability discounting or in perceived risk inherent in reward delay.

Stress-related increases in risk taking and attentional failures predict earlier relapse to smoking in young adults: A pilot investigation

Substantial evidence links greater impulsivity and stress exposure to poorer smoking cessation outcomes. Results from adolescents also indicate that stress-related change in risk taking can impede cessation attempts. We investigated the effects of stress-related change in impulsivity, risk taking, attention and nicotine withdrawal, and craving in young adult smokers on time to smoking relapse in a relapse analogue paradigm. Twenty-six young adult smokers (50% women; mean age: 20.9 ± 1.8) were exposed to a stress imagery session followed by a contingency management-based relapse analogue paradigm. Participants smoked at least 5 cigarettes daily, with a mean baseline carbon monoxide (CO) level of 13.7 (± 5.1) ppm. Repeated measures analysis of variance (ANOVA) and paired t tests examined stress induction validity and Cox regressions of proportional hazards examined the effects of stress-related changes in nicotine withdrawal, nicotine craving, attention, impulsivity, and risk taking on time to relapse. While stress-related change in impulsivity, nicotine craving and withdrawal did not predict time to relapse (all ps > .10), greater stress-related increases in reaction time (RT) variability (p = .02) were predictive of shorter time to relapse, with trend-level findings for inattention and risk taking. Furthermore, changes in stress-related risk taking affected outcome in women more than in men, with a significant relationship between stress-related change in risk taking only in women (p = .026). Smoking cessation attempts in young adults may be adversely impacted by stress-related increases in risk taking and attentional disruption. Clinicians working with young adults attempting cessation may need to target these stress-related impairments by fostering more adaptive coping and resilience.

Reliability and validity of measures of impulsive choice and impulsive action in smokers trying to quit

Cross-sectional research suggests that smokers are more impulsive than are nonsmokers, but few studies have examined relations between impulsiveness and later success in quitting smoking. The purpose of this study was to investigate the reliability and predictive validity of facets of impulsiveness in adult smokers trying to quit. Baseline behavioral measures of impulsive choice (assessed with a delay discounting task) and impulsive action (assessed with a measure of behavioral disinhibition) were used as predictors of smoking cessation success over 12 weeks. The sample included 116 adult (18 years old or older) daily smokers from central New Jersey. Impulsive choice, impulsive action, and self-reported impulsiveness were not significantly related to one another at baseline. Impulsive choice had high test-retest reliability from pre- to postquit, whereas impulsive action was less stable. Test-retest reliability from prequit to 3 weeks' postquit was moderated by achievement of 7-day abstinence. Baseline impulsive action was significantly negatively related to quitting for at least 1 day in the first 2 weeks of a quit attempt and of prolonged abstinence (no relapse over the next 10 weeks). Baseline impulsive choice was robustly associated with biochemically verified 7-day point-prevalence abstinence 12 weeks' postquit, such that those with lower delay discounting were more likely to achieve abstinence. Facets of impulsiveness appear to function largely independently in adult smokers, as indicated by their lack of intercorrelation, differential stability, and differential relations with abstinence. Impulsive action may impede initial quitting, whereas impulsive choice may be an obstacle to maintaining lasting abstinence.

Infection of male rats with Toxoplasma gondii induces effort-aversion in a T-maze decision-making task

Rats chronically infected with protozoan Toxoplasma gondii exhibit greater delay aversion in an inter-temporal task. Moreover T. gondii infection also results in dendritic atrophy of basolateral amygdala neurons. Basolateral amygdala is reported to bias decision making towards greater effortful alternatives. In this context, we report that T. gondii increases effort aversion in infected male rats. This host-parasite association has been widely studied in the context of loss of innate fear in the infected males. It is suggested that reduced fear towards predators reflects a parasitic behavioral manipulation to enhance trophic transmission of T. gondii. Observations reported here extend this paradigm away from a monolithic change in fear and towards a multi-dimensional change in decision making.

Neurophysiological, psychological and behavioural correlates of rTMS treatment in alcohol dependence

BACKGROUND

Addiction is associated with dorso-lateral prefrontal cortex (DLPFC) dysfunction and altered brain-oscillations. High frequency repetitive transcranial magnetic stimulation (HFrTMS) over DLPFC reportedly reduces drug craving. Its effects on neuropsychological, behavioural and neurophysiological are unclear.

METHODS

We assessed psychological, behavioural and neurophysiological effects of 4 sessions of 10-min adjunctive HFrTMS over the left DLPFC during two weeks during a residential programme for alcohol detoxification. Participants were randomized to active HFrTMS (10 Hz, 100% motor threshold) or sham. Immediately before the first and after the last session, 32-channels EEG was recorded and alcohol craving Visual Analogue Scale, Symptom Check List-90-R, Numeric Stroop task and Go/No-go task administered. Tests were repeated at 1-month follow-up.

RESULTS

17 subjects (mean age 44.7 years, 4 F) were assessed. Active rTMS subjects performed better at Stroop test at end of treatment (p=0.036) and follow up (p=0.004) and at Go-NoGo at end of treatment (p=0.05) and follow up (p=0.015). Depressive symptoms decreased at end of active treatment (p=0.036). Active-TMS showed an overall decrease of fast EEG frequencies after treatment compared to sham (p=0.026). No significant modifications over time or group emerged for craving and number of drinks at follow up.

CONCLUSION

4 HFrTMS sessions over two weeks on the left DLPFC can improve inhibitory control task and selective attention and reduce depressive symptoms. An overall reduction of faster EEG frequencies was observed. Nonetheless, this schedule is ineffective in reducing craving and alcohol intake.

Impulsivity moderates the relationship between previous quit failure and cue-induced craving

INTRODUCTION

Poor inhibitory control has been shown to be an important predictor of relapse to a number of drugs, including nicotine. Indeed, smokers who exhibit higher levels of impulsivity are thought to have impaired regulation of urges to smoke, and previous research has suggested that impulsivity may moderate cue-induced cigarette cravings. To that end, we conducted a study to evaluate the interplay between failed smoking cessation, cue-induced craving, and impulsivity.

METHODS

Current smokers (n=151) rated their cigarette cravings before and after laboratory to exposure to smoking cues, and completed questionnaires assessing impulsivity and previous failed quit attempts.

RESULTS

Findings indicated that shorter duration of previous failed quit attempts was related to higher cue-induced cigarette craving, especially among smokers with higher levels of impulsivity.

CONCLUSIONS

Results underscore the importance of considering trait impulsivity as a factor in better understanding the management of cue-induced cravings.

Impulsivity and cigarette craving among adolescent daily and occasional smokers

INTRODUCTION

Impulsivity is a multi-dimensional construct that is robustly related to cigarette smoking. While underlying factors that account for this relation are not well understood, craving has been proposed as a central mechanism linking impulsivity to smoking. In order to further refine our understanding of associations between impulsivity and cigarette craving, the current study examined the association between impulsivity and tonic and cue-elicited craving among a sample of adolescent smokers. We expected trait impulsivity would be positively associated with both tonic and cue-elicited craving, and that this relationship would be stronger among daily vs. occasional smokers.

METHODS

106 smokers (ages 16-20) completed the questionnaires and reported their cigarette craving prior to and immediately following presentation of each of three counterbalanced cue types: (a) in vivo smoking, (b) alcohol, and (c) neutral cue.

RESULTS

Impulsivity was positively associated with tonic craving for daily smokers (β=.38; p=.005), but not occasional smokers (β=.01; p=.95), with a significant impulsivity x smoker group interaction (β=1.31; p=.03). Impulsivity was unrelated to craving following smoking or alcohol cue, regardless of smoker group (all p's>.16).

CONCLUSIONS

Results suggest a moderated effect in which impulsivity is positively associated with tonic craving for daily smokers, but not occasional smokers. Tonic craving may serve as a mechanism linking impulsivity, smoking persistence, and nicotine dependence among daily smokers.

Distinct domains of impulsivity are impaired in juvenile myoclonic epilepsy but not in temporal lobe epilepsy

OBJECTIVE

The Barratt Impulsiveness Scale (BIS-11) is the most widely used questionnaire to study impulsivity in persons with psychiatric disorders, but it has rarely been applied to persons with epilepsy. The present study aimed to evaluate the usefulness of BIS-11 as a tool to explore impulsivity in two distinct epilepsy syndromes.

METHOD

The BIS-11 was applied to 20 patients with juvenile myoclonic epilepsy (JME) (32.5±8.95years old), 20 patients with temporal lobe epilepsy (TLE) (37.7±13.25years old), and 26 healthy controls (31.86±11.25years old). The scores in motor, attentional, and lack of planning impulsivity were compared between groups.

RESULTS

Patients with JME showed higher scores than patients with TLE and controls in all domains: motor (JME vs TLE: 28.60 vs 13.25 (mean score), p<0.001 and JME vs controls: 28.60 vs 14.12, p<0.001), attentional (JME vs TLE: 21.55 vs 13.45, p<0.001 and JME vs controls: 21.55 vs 14.88, p<0.001) and nonplanning (JME vs TLE: 28.05 vs 13.10, p<0.001 and JME vs controls: 28.05 vs 16.15, p<0.001).

CONCLUSION

Higher BIS-11 scores in all domains of impulsivity [i.e., motor, attentional, and lack of planning] corroborated previous findings described in patients with JME. On the other hand, BIS-11 could not demonstrate problem solving and inhibitory control deficits related to impulsive behavior, which were described in patients with TLE. Other behavioral measures may be more sensitive to some aspects of impulsivity in TLE. Our results reinforce the concept that distinct epileptic syndromes require different neuropsychological approaches, especially considering a complex construct such as impulsivity.

Increased impulsivity in pathological gambling: Considering nicotine dependence

INTRODUCTION

It has been highlighted that increased impulsivity is an important etiological factor in pathological gambling (PG). However, the role of the highly prevalent comorbid mental disorders in PG remains unclear. This is of special concern as the highest comorbidity was found between PG and nicotine dependence (ND), which, in turn, has also been associated with heightened impulsivity. This study aimed to find out whether increased impulsivity in PG is a specific characteristic related to comorbid mental disorders in general or especially to ND.

METHOD

A cross-sectional study was designed that included a healthy control group and three disorder groups with comorbid PG excluding ND, comorbid PG including ND, and ND alone according to the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition. Impulsivity was assessed according to the dimensions response and choice impulsivity applying behavioral and self-report measures.

RESULTS

We found (a) increased response impulsivity in the comorbid PG group when compared to the control group. Furthermore, increased choice impulsivity was found (b) in comorbid PG excluding ND and (c) in comorbid PG including ND when compared to ND alone. Other group differences did not reach significance.

CONCLUSIONS

Our findings highlight that comorbid PG shares deficits in inhibitory control with ND. In contrast, maladaptive choices are a specific disorder characteristic of comorbid PG when compared to ND. If replicated in further studies, intervention strategies strengthening cognitive control skills might be effective for comorbid PG as well as ND whereas strategies enhancing maladaptive valuation of rewards might be specifically effective in comorbid PG.

Pharmacogenetics of nicotine and associated smoking behaviors

This chapter summarizes genetic factors that contribute to variation in nicotine pharmacokinetics and nicotine's pharmacological action in the central nervous system (CNS), and how this in turn influences smoking behaviors. Nicotine, the major psychoactive compound in cigarette smoke, is metabolized by a number of enzymes, including CYP2A6, CYP2B6, FMOs, and UGTs, among others. Variation in the genes encoding these enzymes, in particular CYP2A6, can alter the rate of nicotine metabolism and smoking behaviors. Faster nicotine metabolism is associated with higher cigarette consumption and nicotine dependence, as well as lower quit rates. Variation in nicotine's CNS targets and downstream signaling pathways can also contribute to interindividual differences in smoking patterns. Binding of nicotine to neuronal nicotinic acetylcholine receptors (nAChRs) mediates the release of several neurotransmitters including dopamine and serotonin. Genetic variation in nAChRs, and in transporter and enzyme systems that leads to altered CNS levels of dopamine and serotonin, is associated with a number of smoking behaviors. To date, the precise mechanism underpinning many of these findings remains unknown. Considering the complex etiology of nicotine addiction, a more comprehensive approach that assesses the contribution of multiple gene variants, and their interaction with environmental factors, will likely improve personalized therapeutic approaches and increase smoking cessation rates.

Cigarette Cravings, Impulsivity, and the Brain

Craving is a core feature of tobacco use disorder as well as a significant predictor of smoking relapse. Studies have shown that appetitive smoking-related stimuli (e.g., someone smoking) trigger significant cravings in smokers impede their self-control capacities and promote drug seeking behavior. In this review, we begin by an overview of functional magnetic resonance imaging (fMRI) studies investigating the neural correlates of smokers to appetitive smoking cues. The literature reveals a complex and vastly distributed neuronal network underlying smokers' craving response that recruits regions involved in self-referential processing, planning/regulatory processes, emotional responding, attentional biases, and automatic conducts. We then selectively review important factors contributing to the heterogeneity of results that significantly limit the implications of these findings, namely between- (abstinence, smoking expectancies, and self-regulation) and within-studies factors (severity of smoking dependence, sex-differences, motivation to quit, and genetic factors). Remarkably, we found that little to no attention has been devoted to examine the influence of personality traits on the neural correlates of cigarette cravings in fMRI studies. Impulsivity has been linked with craving and relapse in substance and tobacco use, which prompted our research team to examine the influence of impulsivity on cigarette cravings in an fMRI study. We found that the influence of impulsivity on cigarette cravings was mediated by fronto-cingulate mechanisms. Given the high prevalence of cigarette smoking in several psychiatric disorders that are characterized by significant levels of impulsivity, we conclude by identifying psychiatric patients as a target population whose tobacco-smoking habits deserve further behavioral and neuro-imaging investigation.

Effects of acute and repeated nicotine administration on delay discounting in Lewis and Fischer 344 rats

Biological differences may underlie individual differences in impulsive behavior, such as choice for a smaller, more immediate reinforcer over a larger, more delayed reinforcer. Repeated exposure to drugs of abuse may have different effects on such behavior. To evaluate the acute and repeated effects of nicotine on impulsive choice, two strains of rats that have been shown to differ in impulsive choice were tested in a delay-discounting paradigm. Eight Lewis and eight Fischer 344 rats were allowed to choose between one food pellet delivered immediately and three food pellets delivered after a delay. The delay systematically increased in blocks of trials within each session, and the delay value at which the choice for the two alternatives was equal (i.e. the indifference point) was interpolated. Effects of nicotine (0.1-1.0 mg/kg, subcutaneous) on percent choice and indifference points were determined during the acute-testing phase and during the redetermination of effects of each dose after at least 30 sessions of repeated 1.0 mg/kg nicotine exposure. The Lewis rats had shorter indifference points (i.e. made fewer larger-reinforcer choices) compared with the Fischer 344 rats. Acute nicotine administration increased the mean larger-reinforcer choices at the 0.3 mg/kg dose in the Lewis rats and at the 1.0 mg/kg dose in the Fischer 344 rats. After repeated exposure to nicotine, indifference points returned to near-baseline (predrug) levels for both the strains. Strain differences were observed in the rates of delay discounting, and nicotine may decrease the impulsive choice acutely, but this effect does not seem to be long lasting.

Targeting the nicotinic cholinergic system to treat attention-deficit/hyperactivity disorder: rationale and progress to date

Attention-deficit/hyperactivity disorder (ADHD) is a common chronic neurobehavioral disorder related to clinically significant levels of inattention, hyperactivity, and/or impulsivity. ADHD begins in childhood and symptoms persist into adulthood for the majority of those with the disorder. Associated features of ADHD include emotion dysregulation and cognitive impairments, which contribute to the considerable functional impairments in this disorder. Current approved treatments are reasonably effective; however, a significant need remains for new pharmacotherapies, both for individuals who do not achieve a full therapeutic response and for symptoms that are under-treated including cognition and emotion regulation. The striking relationship between ADHD and cigarette smoking and the known effects of nicotine on cognition has spurred research into the therapeutic potential of nicotinic agents for ADHD. Although there are no approved medications for ADHD that target nicotinic acetylcholine receptor (nAChR) function, results from many trials of nicotinic drugs are available and reviewed in this article. ADHD symptoms were reduced in the majority of published studies of nicotine and novel α4β2 nicotinic agonists in adult ADHD. The drugs were generally well tolerated, with mild to moderate side effects reported, which were largely consistent with cholinergic stimulation and included nausea, dizziness, and gastrointestinal distress. Within-subject crossover study designs were used in the majority of positive studies. This design may be particularly useful in ADHD trials because it minimizes variability in this notoriously heterogeneous diagnostic group. In addition, many studies found evidence for a beneficial effect of nicotinic stimulation on cognitive and emotional domains. Thus, targeting nAChRs in ADHD appears to have a modest clinical benefit in adult ADHD. Continued refinement of nAChR agonists with greater specificity and fewer side effects may lead to even more effective nAChR agonists for ADHD. Future clinical trials in ADHD should include direct measures of neuropsychological performance and emotion regulation.

Delay and probability discounting of multiple commodities in smokers and never-smokers using multiple-choice tasks

The purpose of the present study was to investigate temporal and probabilistic discounting in smokers and never-smokers, across a number of commodities, using a multiple-choice method. One hundred and eighty-two undergraduate university students, of whom 90 had never smoked, 73 were self-reported light smokers (<10 cigarettes/day), and 17 were heavy smokers (10+cigarettes/day), completed computerized batteries of delay and probability discounting questions pertaining to a total of eight commodities and administered in a multiple-choice format. In addition to cigarettes, monetary rewards, and health outcomes, the tasks included novel commodities such as ideal dating partner and retirement income. The results showed that heavy smokers probability discounted commodities at a significantly shallower rate than never-smokers, suggesting greater risk-taking. No effect of smoking status was observed for delay discounting questions. The only commodity that was probability discounted significantly less than others was 'finding an ideal dating partner'. The results suggest that probability discounting tasks using the multiple-choice format can discriminate between non-abstaining smokers and never-smokers and could be further explored in the context of behavioral and drug addictions.

Dimensions and disorder specificity of impulsivity in pathological gambling

Impulsivity is a core characteristic of pathological gambling (PG), even though the underlying structure and disorder specificity is unclear. This study aimed to explore different dimensions of impulsivity in a clinical sample including PG. Furthermore, we aimed to test which alterations of the impulsivity-related dimensions are disorder specific for PG. Participants were individuals diagnosed with PG (n=51) and two groups also characterized by various impulsive behaviors: an alcohol dependence (AD; n=45) and a Gilles de la Tourette syndrome (GTS; n=49) group. A healthy control (HC; n=53) group was recruited as comparison group. A comprehensive assessment was used including impulsivity-related and antipodal parameters of the Stop Signal Task, Stroop Task, Tower of London Task, Card Playing Task, Iowa Gambling Task and the Barratt Impulsiveness Scale-11. Principal axis factor analysis revealed four impulsivity-related dimensions that were labeled 'self-reported impulsivity', 'prepotent response impulsivity', 'choice impulsivity' and 'motor impulsivity'. The PG group scored significantly higher on all four dimensions compared to the HC group. In contrast, the PG group did not differ on any of the dimensions from the AD or the GTS group, except for 'choice impulsivity' where the PG group exhibited higher factor scores compared to the GTS group. Altogether, PG is associated with generally heightened impulsivity profiles compared to a HC group, which may be further used for intervention strategies. However, heightened scores in the impulsivity dimensions are not disorder specific for PG. Further research on shared or different underlying mechanisms of these overlapping impulsivity impairments is necessary.

Cigarette smoking and measures of impulsivity in a college sample

BACKGROUND

An association between impulsivity and smoking has been consistently reported in the literature, but few studies have examined how distinct dimensions of impulsivity may relate differentially to smoking initiation versus persistent smoking. The aim of the current study was to examine the relationship between self-report and behavioral measures of impulsivity and smoking status in college students.

METHODS

Participants (N = 243) completed a self-report history of tobacco use, 2 self-report measures of impulsivity (the Barratt Impulsiveness Scale and Zuckerman Sensation-Seeking Scale), and 2 behavioral measures (the Delay Discounting Task and Iowa Gambling Task). All participants were classified as never-smokers, triers, or smokers based on their smoking history, and between-group differences on the 4 measures were examined.

RESULTS

On the self-report measures, all 3 groups differed on sensation seeking, with the never-smokers reporting the lowest levels and the smokers reporting the highest. Furthermore, the smokers reported significantly higher disinhibitory impulsivity than the triers and never-smokers. The groups did not differ on the behavioral measures.

CONCLUSIONS

These results indicate that distinct dimensions of impulsivity characterize different smoking phenotypes. In particular, sensation seeking is associated with the initiation of smoking, whereas disinhibitory impulsivity is associated with the transition to more persistent and regular use of cigarettes.

Impulsivity as a predictor of treatment outcome in substance use disorders: review and synthesis

ISSUES

Impulsivity is a widely studied personality trait and research construct that has been implicated as a risk factor for substance use, including initiating and continuing use. However, relatively few studies have examined impulsivity as a predictor of treatment outcome. Because impulsivity has been operationalised in many different ways, cross-comparisons of empirical studies have been difficult.

APPROACH

The PubMed database was searched in September 2013. Reference lists of papers retrieved from this search were also manually scanned for additional resources. Studies were included if they presented data that assessed impulsivity as a predictor of treatment outcomes.

KEY FINDINGS

The body of literature reviewed in this paper suggests that higher pretreatment impulsivity, regardless of how it is measured, usually is associated with poorer treatment outcomes. Recent data indicate that some psychosocial and pharmacological treatments may directly impact impulsivity and thus represent an interesting avenue for further research.

CONCLUSIONS

Impulsivity appears to be a key predictor of substance use treatment outcomes and warrants more attention in the improvement of treatment outcomes. Suggestions for future research on the role of impulsivity in substance use treatment are provided.

Dysfunctional decision-making in pathological gambling: pattern specificity and the role of impulsivity

Dysfunctional decision-making in individuals with pathological gambling (PGs) may result from dominating reward-driven processes, indicated by higher impulsivity. In the current study we examined (1) if PGs show specific decision-making impairments related to dominating reward-driven processes rather than to strategic planning deficits and (2) whether these impairments are related to impulsivity. Nineteen PGs according to DSM-IV and 19 matched control subjects undertook the Cambridge Gambling Task (CGT) to assess decision-making. The delay discounting paradigm (DDP) as well as the UPPS Impulsive Behavior Scale (measuring urgency, premeditation, perseverance and sensation seeking) were administered as multidimensional measures of impulsivity. Results revealed that (1) PGs exhibited higher risk seeking and an immediate reward focus in the CGT and, in contrast, comparable strategic planning to the control group. (2) Decision-making impairments were related to more severe delay discounting and, specifically, to increased urgency and less premeditation. Our findings suggest (1) the necessity to disentangle decision-making components in order to improve etiological models of PGs, and (2) that urgency and premeditation are specifically related to disadvantageous decision-making and should be tackled in intervention strategies focusing on emotion tolerance and control strategies.

Contingency management voucher redemption as an indicator of delayed gratification

This prospective analysis tested whether frequency of voucher redemptions during a contingency management (CM) substance use intervention was significantly associated with participants' ongoing substance use. Homeless, substance-dependent men who have sex with men (N=131) were randomized into either a "full" or "lite" voucher-based CM intervention. All participants earned vouchers for attendance and participation; participants in the CM-full condition also received vouchers for substance abstinence and enactment of prosocial and/or health-promoting behaviors. Multivariate longitudinal negative binomial regression analyses (n=118) assessed the association between substance use during the intervention and frequency of voucher redemptions. Participants who used methamphetamine (IRR=0.66; 95% CI=0.44-0.99) and/or opiates (IRR=0.60; 95% CI=0.40-0.99) during the intervention exhibited less time between voucher redemptions than individuals who achieved abstinence from these substances. Voucher redemption logs can be cost-effective and unobtrusive tools for measuring study participants' tendency to delay gratification.

Cigarette smoking in obsessive-compulsive disorder and unaffected parents of OCD patients

BACKGROUND

Cigarette smoking is more prevalent among individuals with psychiatric disorders than the general population. Obsessive-compulsive disorder (OCD) may be an intriguing exception, although no recent study has investigated this hypothesis in OCD patients. Moreover, it is unknown whether reduced smoking rates are present in unaffected first-degree relatives of OCD patients.

METHODS

We assessed smoking prevalence in adults with OCD and unaffected parents of youth with OCD (PYOCD). To this end, 113 adults with OCD completed online questionnaires assessing symptom severity and smoking status. Smoking status was obtained from an independent sample of 210 PYOCD assessed for psychiatric diagnoses.

RESULTS

Smoking prevalence rates in adults with OCD (13.3%; n=15) and PYOCD (9.5%; n=20) samples were significantly lower than those found in representative samples of the general population (19-24%, all P<.001) and Axis I disorders (36-64%; all P<.001). There were no smokers in the adult OCD subset without clinically significant depressive symptoms (n=54).

CONCLUSION

Low prevalence of smoking in OCD may be familial and unique among psychiatric disorders, and might represent a possible state-independent OCD marker. Hypotheses concerning the uncharacteristically low prevalence rates are discussed with relation to OCD phenomenology and pathophysiology.

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.