Effects of varenicline on smoking cue–triggered neural and craving responses

Parameter Space and Potential for Biomarker Development in 25 Years of fMRI Drug Cue Reactivity: A Systematic Review

Importance

In the last 25 years, functional magnetic resonance imaging drug cue reactivity (FDCR) studies have characterized some core aspects in the neurobiology of drug addiction. However, no FDCR-derived biomarkers have been approved for treatment development or clinical adoption. Traversing this translational gap requires a systematic assessment of the FDCR literature evidence, its heterogeneity, and an evaluation of possible clinical uses of FDCR-derived biomarkers.

Objective

To summarize the state of the field of FDCR, assess their potential for biomarker development, and outline a clear process for biomarker qualification to guide future research and validation efforts.

Evidence Review

The PubMed and Medline databases were searched for every original FDCR investigation published from database inception until December 2022. Collected data covered study design, participant characteristics, FDCR task design, and whether each study provided evidence that might potentially help develop susceptibility, diagnostic, response, prognostic, predictive, or severity biomarkers for 1 or more addictive disorders.

Findings

There were 415 FDCR studies published between 1998 and 2022. Most focused on nicotine (122 [29.6%]), alcohol (120 [29.2%]), or cocaine (46 [11.1%]), and most used visual cues (354 [85.3%]). Together, these studies recruited 19 311 participants, including 13 812 individuals with past or current substance use disorders. Most studies could potentially support biomarker development, including diagnostic (143 [32.7%]), treatment response (141 [32.3%]), severity (84 [19.2%]), prognostic (30 [6.9%]), predictive (25 [5.7%]), monitoring (12 [2.7%]), and susceptibility (2 [0.5%]) biomarkers. A total of 155 interventional studies used FDCR, mostly to investigate pharmacological (67 [43.2%]) or cognitive/behavioral (51 [32.9%]) interventions; 141 studies used FDCR as a response measure, of which 125 (88.7%) reported significant interventional FDCR alterations; and 25 studies used FDCR as an intervention outcome predictor, with 24 (96%) finding significant associations between FDCR markers and treatment outcomes.

Conclusions and Relevance

Based on this systematic review and the proposed biomarker development framework, there is a pathway for the development and regulatory qualification of FDCR-based biomarkers of addiction and recovery. Further validation could support the use of FDCR-derived measures, potentially accelerating treatment development and improving diagnostic, prognostic, and predictive clinical judgments.

Changes in distinct brain systems identified with fMRI during smoking cessation treatment with varenicline: a review

BACKGROUND

Varenicline is considered one of the most effective treatment options for smoking cessation. Nonetheless, it is only modestly effective. A deeper comprehension of the effects of varenicline by means of the in-depth review of relevant fMRI studies may assist in paving the development of more targeted and effective treatments.

METHODOLOGY

A search of PubMed and Google Scholar databases was conducted with the keywords "functional magnetic resonance imaging" or "fMRI", and "varenicline". All peer-reviewed articles regarding the assessment of smokers with fMRI while undergoing treatment with varenicline and meeting the predefined criteria were included.

RESULTS

Several studies utilizing different methodologies and targeting different aspects of brain function were identified. During nicotine withdrawal, decreased mesocorticolimbic activity and increased amygdala activity, as well as elevated amygdala-insula and insula-default-mode-network functional connectivity are alleviated by varenicline under specific testing conditions. However, other nicotine withdrawal-induced changes, including the decreased reward responsivity of the ventral striatum, the bilateral dorsal striatum and the anterior cingulate cortex are not influenced by varenicline suggesting a task-dependent divergence in neurocircuitry activation. Under satiety, varenicline treatment is associated with diminished cue-induced activation of the ventral striatum and medial orbitofrontal cortex concomitant with reduced cravings; during the resting state, varenicline induces activation of the lateral orbitofrontal cortex and suppression of the right amygdala.

CONCLUSIONS

The current review provides important clues with regard to the neurobiological mechanism of action of varenicline and highlights promising research opportunities regarding the development of more selective and effective treatments and predictive biomarkers for treatment efficacy.

Combining neuroimaging and brain stimulation to test alternative causal pathways for nicotine addiction in schizophrenia

The smoking rate is high in patients with schizophrenia. Brain stimulation targeting conventional brain circuits associated with nicotine addiction has also yielded mixed results. We aimed to identify alternative circuitries associated with nicotine addiction in both the general population and schizophrenia, and then test whether modulation of such circuitries may alter nicotine addiction behaviors in schizophrenia. In Study I of 40 schizophrenia smokers and 51 non-psychiatric smokers, cross-sectional neuroimaging analysis identified resting state functional connectivity (rsFC) between the dorsomedial prefrontal cortex (dmPFC) and multiple extended amygdala regions to be most robustly associated with nicotine addiction severity in healthy controls and schizophrenia patients (p = 0.006 to 0.07). In Study II with another 30 patient smokers, a proof-of-concept, patient- and rater-blind, randomized, sham-controlled rTMS design was used to test whether targeting the newly identified dmPFC location may causally enhance the rsFC and reduce nicotine addiction in schizophrenia. Although significant interactions were not observed, exploratory analyses showed that this dmPFC-extended amygdala rsFC was enhanced by 4-week active 10Hz rTMS (p = 0.05) compared to baseline; the severity of nicotine addiction showed trends of reduction after 3 and 4 weeks (p ≤ 0.05) of active rTMS compared to sham; Increased rsFC by active rTMS predicted reduction of cigarettes/day (R = -0.56, p = 0.025 uncorrected) and morning smoking severity (R = -0.59, p = 0.016 uncorrected). These results suggest that the dmPFC-extended amygdala circuit may be linked to nicotine addiction in schizophrenia and healthy individuals, and future efforts targeting its underlying pathophysiological mechanisms may yield more effective treatment for nicotine addiction.

Reduced executive and reward connectivity is associated with smoking cessation response to repetitive transcranial magnetic stimulation: A double-blind, randomized, sham-controlled trial

Repetitive transcranial magnetic stimulation (rTMS) can reduce cue-elicited craving, decrease cigarette consumption, and increase the abstinence rate in tobacco use disorders (TUDs). We used functional magnetic resonance imaging (fMRI) to investigate the effect of 10 sessions of rTMS on cortical activity and neural networks in treatment-seeking smokers. Smoking cue exposure fMRI scans were acquired before and after the 10 sessions of active or sham rTMS (10 Hz, 3000 pulses per session) to the left dorsal lateral prefrontal cortex (DLPFC) in 42 treatment-seeking smokers (≥ 10 cigarettes per day). Brain activity and functional connectivity were compared before and after 10 sessions of rTMS. Ten sessions of rTMS significantly reduced the number of cigarettes consumed per day (62.93%) compared to sham treatment (39.43%) at the end of treatment (p = 0.027). fMRI results showed that the rTMS treatment increased brain activity in the dorsal anterior cingulate cortex (dACC) and DLPFC, but decreased brain activity in the bilateral medial orbitofrontal cortex (mOFC). The lower strength of dACC and mOFC connectivity was associated with quitting smoking (Wald score = 5.00, p = 0.025). The reduction of cigarette consumption significantly correlated with the increased brain activation in the dACC (r = 0.76, p = 0.0001). By increasing the brain activity in the dACC and prefrontal cortex and decreasing brain activity in the mOFC, 10 sessions of rTMS significantly reduced cigarette consumption and increased quit rate. Reduced drive-reward and executive control functional connectivity was associated with the smoking cessation effect from rTMS. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02401672.

Exploring the Utility of a Functional Magnetic Resonance Imaging (fMRI) Cannabis Cue-Reactivity Paradigm in Treatment Seeking Adults with Cannabis Use Disorder

Introduction

Functional magnetic resonance imaging (fMRI) studies examining cue-reactivity in cannabis use disorder (CUD) to date have either involved non-treatment seeking participants or been small. We addressed this gap by administering an fMRI cue-reactivity task to CUD participants entering two separate clinical trials.

Methods

Treatment-seeking participants with moderate or severe CUD had behavioral craving measured at baseline via the Marijuana Craving Questionnaire (MCQ-SF). They additionally completed a visual cannabis cue-reactivity paradigm during fMRI following 24-hours of abstinence from cannabis. During fMRI, the Blood Oxygen Level Dependent (BOLD) signal was acquired while participants viewed cannabis-images or matched-neutral-images. BOLD responses were correlated with the MCQ-SF using a General Linear Model.

Results

N=65 participants (32% female; mean age 30.4±9.9SD) averaged 46.3±15.5SD on the MCQ-SF. When contrasting cannabis-images vs. matched-neutral-images, participants showed greater BOLD response in bilateral ventromedial prefrontal, dorsolateral prefrontal, anterior cingulate, and visual cortices, as well as the striatum. Similarly, there was stronger task-based functional-connectivity (tbFC) between the medial prefrontal cortex and both the amygdala and the visual cortex. There were no significant differences in either activation or tbFC between studies or between sexes. Craving negatively correlated with BOLD response in the left ventral striatum (R 2 =-0.25; p =0.01).

Conclusions

We found that, among two separate treatment-seeking CUD groups, cannabis cue-reactivity was evidenced by greater activation and tbFC in regions related to executive function and reward processing, and craving was negatively associated with cue-reactivity in the ventral striatum. Future directions include examining if pharmacological, neuromodulatory, or psychosocial interventions can alter corticostriatal cue-reactivity.

Cue-reactivity targeted smoking cessation intervention in individuals with tobacco use disorder: a scoping review

Objectives

Cue-reactivity is a critical step leading to the emergence of addictive psychology and the triggering of addictive behaviors within the framework of addiction theory and is considered a significant risk factor for addiction-related behaviors. However, the effect of cue-reactivity targeted smoking cessation intervention and the cue-reactivity paradigms used in the randomized controlled trials varies, which introduces more heterogeneity and makes a side-by-side comparison of cessation responses difficult. Therefore, the scoping review aims to integrate existing research and identify evidence gaps.

Methods

We searched databases in English (PubMed and Embase) and Chinese (CNKI and Wanfang) using terms synonymous with 'cue' and 'tobacco use disorder (TUD)' to April 2023, and via hand-searching and reference screening of included studies. Studies were included if they were randomized controlled trials taking cue-reactivity as an indicator for tobacco use disorder (TUD) defined by different kinds of criteria.

Results

Data were extracted on each study's country, population, methods, timeframes, outcomes, cue-reactivity paradigms, and so on. Of the 2,944 literature were retrieved, 201 studies met the criteria and were selected for full-text screening. Finally, 67 pieces of literature were selected for inclusion and data extraction. The results mainly revealed that non-invasive brain stimulation and exercise therapy showed a trend of greater possibility in reducing subjective craving compared to the remaining therapies, despite variations in the number of research studies conducted in each category. And cue-reactivity paradigms vary in materials and mainly fall into two main categories: behaviorally induced craving paradigm or visually induced craving paradigm.

Conclusion

The current studies are still inadequate in terms of comparability due to their heterogeneity, cue-reactivity can be conducted in the future by constructing a standard library of smoking cue materials. Causal analysis is suggested in order to adequately screen for causes of addiction persistence, and further explore the specific objective cue-reactivity-related indicators of TUD.

Active versus sham transcranial direct current stimulation (tDCS) as an adjunct to varenicline treatment for smoking cessation: Study protocol for a double-blind single dummy randomized controlled trial

BACKGROUND

Smoking is a chronic and relapsing disease, with up to 60% of quitters relapsing within the first year. Transcranial Direct Current Stimulation (tDCS), targets cortical circuits and acutely reduces craving and withdrawal symptoms among cigarette smokers. However, the efficacy of tDCS as an adjunct to standard smoking cessation treatments has not been studied. This study aims to investigate the effectiveness of tDCS in combination with varenicline for smoking cessation. We hypothesize that active tDCS combined with varenicline will improve cessation outcomes compared to sham tDCS combined with varenicline.

METHODS

This is a double-blind, sham-controlled randomized clinical trial where fifty healthy smokers will be recruited in Toronto, Canada. Participants will be randomized 1:1 to either active tDCS (20 minutes at 2 mA) or sham tDCS (30 seconds at 2 mA, 19 minutes at 0 mA) for 10 daily sessions (2 weeks) plus 5 follow up sessions, occurring every two weeks for 10 weeks. All participants will be given standard varenicline treatment concurrently for the 12-week treatment period. The primary outcome is 30 day continuous abstinence at end of treatment, confirmed with urinary cotinine. Measurements made at each study visit include expired carbon monoxide, self-reported craving and withdrawal. Three magnetic resonance imaging (MRI) scans will be conducted: two at baseline and one at end of treatment, to assess any functional or structural changes following treatment.

DISCUSSION

For every two smokers who quit, one life is saved from a tobacco-related mortality. Therefore, it is important to develop new and more effective treatment approaches that can improve and maintain long-term abstinence, in order to decrease the prevalence of tobacco-related deaths and disease. Furthermore, the addition of longitudinal neuroimaging can shed light on neural circuitry changes that might occur as a result of brain stimulation, furthering our understanding of tDCS in addiction treatment.

TRIAL REGISTRATION

This trial has been registered with Clinicaltrials.gov: NCT03841292 since February 15th 2019 (https://clinicaltrials.gov/ct2/show/NCT03841292)-retrospectively registered.

Smokers’ Self-Report and Behavioral Reactivity to Combined Personal Smoking Cues (Proximal + Environment + People): A Pilot Study

Cue reactivity (CR) among smokers exposed to smoking-related stimuli, both proximal (e.g., cigarettes, lighter) and distal (environments, people), has been well-demonstrated. Furthermore, past work has shown that combining proximal smoking cues with smoking environment cues increases cue-provoked craving and smoking behavior above that elicited by either cue type alone. In this pilot study, we examined the impact of combining three personal cues, proximal + environment + people, on subjective and behavioral cue reactivity among smokers. To further understand the impact of this method, we also tested reactivity under the conditions of both smoking satiety and deprivation. In addition, we examined the extent to which cue-induced craving predicted immediate subsequent smoking. Fifteen smokers completed six sessions, of which two focused on the intake and development of personal cues and four involved personal cue reactivity sessions: (1) deprived, smoking cue combination, (2) deprived, nonsmoking cue combination, (3) sated, smoking combination, and (4) sated, nonsmoking cue combination. Cue-provoked craving was greater and smokers were quicker to light a cigarette and smoked more during their exposure to smoking rather than nonsmoking cues and in deprived compared to sated conditions, with no interaction between these variables. While deprived, greater cue-provoked craving in response to smoking cues was correlated with a quicker latency to light a cigarette. This work supports the feasibility of presenting three personal smoking-related combinations of cues within a cue reactivity paradigm and highlights the robust reactivity that this methodology can evoke in smokers.

Effects of varenicline and bupropion on laboratory smoking outcomes: Meta-analysis of randomized, placebo-controlled human laboratory studies

Human laboratory studies are widely used to evaluate behavioural mechanisms of pharmacotherapy effects. Results from human laboratory studies examining smoking cessation pharmacotherapies have not been examined in aggregate. The current meta-analysis aimed to synthesize data from randomized, placebo-controlled human laboratory studies on the effects of non-nicotine pharmacotherapies on outcomes relevant for smoking cessation. Literature searches identified 15 human laboratory studies of varenicline (n = 697) and 9 studies of bupropion (n = 313) with sufficient data for inclusion. Studies involved acute or subacute pharmacotherapy treatment with administration durations ranging from a single dose to 8 weeks. Primary outcomes examined were craving, withdrawal and behavioural indices of smoking. Varenicline significantly reduced craving (Hedge's g = -0.36[-0.54,-0.17], p < 0.001), withdrawal (g = -0.25[-0.41,-0.09], p = 0.003) and behavioural indices of smoking (g = -0.36[-0.63,-0.08], p = 0.01) relative to placebo. In contrast, results were inconclusive regarding bupropion's effects on craving (g = -0.13[-0.32,0.05], p = 0.15), withdrawal (g = -0.15[-0.44,0.14], p = 0.31) and behavioural indices of smoking (g = -0.05[-0.35,0.24], p = 0.73) relative to placebo. Findings provide meta-analytic support that short-term varenicline treatment decreases craving, withdrawal symptoms and smoking behaviour under controlled laboratory conditions. However, findings also suggest the ability of human laboratory paradigms to detect pharmacotherapy effects may differ by treatment type. Pharmacotherapy discovery and evaluation efforts utilizing human laboratory methods should aim to align study designs and laboratory procedures with presumed therapeutic mechanisms when possible.

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.

Dose-dependent effects of Varenicline on tobacco craving and withdrawal in tobacco smokers with and without schizophrenia

BACKGROUND

People with schizophrenia (SCZ) have significantly higher tobacco smoking rates and lower quit rates than the general population. Varenicline, a partial agonist at α4β2 nicotinic acetylcholine receptors (nAChRs) is an effective smoking cessation pharmacotherapy, however, investigation into its effects in SCZ are less well-studied and mechanisms may differ from non-psychiatric controls due to dysregulation in nAChR neurotransmission associated with SCZ. Here, we investigate whether Varenicline attenuates acute abstinence-induced increases in craving and withdrawal in participants with and without SCZ.

METHODS

Following biochemically-verified overnight abstinence and subsequent smoking reinstatement, individuals with nicotine-dependence (n = 13 SCZ or schizoaffective; n = 12 controls) were assessed on the Minnesota Nicotine Withdrawal Scale (MNWS) and Tiffany Questionnaire for Smoking Urges (TQSU). Participants were pretreated in a double-blind, counterbalanced manner with Varenicline (0, 1 or 2 mg/day x 3 days) over three separate weeks. Data were analyzed using linear mixed-effects modelling and estimated marginal means.

RESULTS

Robust effects of smoking abstinence were observed on TQSU and MNWS scores in SCZ and control participants. Relative to 1 mg, 2 mg/day of Varenicline attenuated abstinence-induced increases in craving (TQSU Factor 1 d=-0.47, p = .006; TQSU Factor 2 d=-0.42, p = .008) and withdrawal (MNWS d=-0.35, p = .03) in both groups.

CONCLUSION

Our preliminary findings suggest that subacute Varenicline treatment reduces abstinence-induced craving and withdrawal in participants with and without SCZ. The efficacy of Varenicline on tobacco withdrawal and craving requires further study.

Topiramate decreases the salience of motivationally relevant visual cues among smokers with alcohol use disorder

BACKGROUND

There is preliminary evidence that the anticonvulsant topiramate increases the likelihood of both smoking and alcohol abstinence among smokers with alcohol use disorder (AUD), but its therapeutic mechanism has not been determined. We used event-related potentials (ERPs) to evaluate topiramate's effect on the salience of drug-related, emotional, and neutral pictorial cues to identify whether one of its potential therapeutic mechanisms involves reduction of the salience of motivationally relevant cues.

METHODS

Participants enrolled in a multisite clinical trial treating smokers with AUD were randomly assigned to receive placebo, low-dose topiramate (up to 125 mg/day), or high-dose topiramate (up to 250 mg/day), along with brief behavioral compliance enhancement treatment. A subsample (n = 101) completed ERP assessments at baseline (1 week pre-medication) and week 5 (5 weeks on medication; 1 week pre-quit). We assessed the salience of pleasant, unpleasant, cigarette-related, alcohol-related, and neutral pictorial cues using the late positive potential (LPP) ERP component and measured self-reported substance use, reinforcement, craving, and withdrawal.

RESULTS

Five weeks of high-dose topiramate treatment decreased LPP amplitudes in response to both emotional (pleasant and unpleasant) and drug-related cues (alcohol and cigarette), but not to neutral cues. However, results showed that the LPPs were not significant mediators of the relationship between topiramate dose and post-quit measures of substance use, reinforcement, craving, or withdrawal.

CONCLUSIONS

These findings suggest that high-dose topiramate (up to 250 mg/day) decreases the motivational salience of both drug-related and emotional cues among smokers with AUD. However, the nonsignificant mediation analyses preclude any firm conclusions about whether this effect represents one of topiramate's therapeutic mechanisms of action.

A methodological checklist for fMRI drug cue reactivity studies: development and expert consensus

Cue reactivity is one of the most frequently used paradigms in functional magnetic resonance imaging (fMRI) studies of substance use disorders (SUDs). Although there have been promising results elucidating the neurocognitive mechanisms of SUDs and SUD treatments, the interpretability and reproducibility of these studies is limited by incomplete reporting of participants' characteristics, task design, craving assessment, scanning preparation and analysis decisions in fMRI drug cue reactivity (FDCR) experiments. This hampers clinical translation, not least because systematic review and meta-analysis of published work are difficult. This consensus paper and Delphi study aims to outline the important methodological aspects of FDCR research, present structured recommendations for more comprehensive methods reporting and review the FDCR literature to assess the reporting of items that are deemed important. Forty-five FDCR scientists from around the world participated in this study. First, an initial checklist of items deemed important in FDCR studies was developed by several members of the Enhanced NeuroImaging Genetics through Meta-Analyses (ENIGMA) Addiction working group on the basis of a systematic review. Using a modified Delphi consensus method, all experts were asked to comment on, revise or add items to the initial checklist, and then to rate the importance of each item in subsequent rounds. The reporting status of the items in the final checklist was investigated in 108 recently published FDCR studies identified through a systematic review. By the final round, 38 items reached the consensus threshold and were classified under seven major categories: 'Participants' Characteristics', 'General fMRI Information', 'General Task Information', 'Cue Information', 'Craving Assessment Inside Scanner', 'Craving Assessment Outside Scanner' and 'Pre- and Post-Scanning Considerations'. The review of the 108 FDCR papers revealed significant gaps in the reporting of the items considered important by the experts. For instance, whereas items in the 'General fMRI Information' category were reported in 90.5% of the reviewed papers, items in the 'Pre- and Post-Scanning Considerations' category were reported by only 44.7% of reviewed FDCR studies. Considering the notable and sometimes unexpected gaps in the reporting of items deemed to be important by experts in any FDCR study, the protocols could benefit from the adoption of reporting standards. This checklist, a living document to be updated as the field and its methods advance, can help improve experimental design, reporting and the widespread understanding of the FDCR protocols. This checklist can also provide a sample for developing consensus statements for protocols in other areas of task-based fMRI.

Altered Global Signal Topography in Alcohol Use Disorders

The most common symptom of patients with alcohol use disorders (AUD) is cognitive impairment that negatively affects abstinence. Presently, there is a lack of indicators for early diagnosis of alcohol-related cognitive impairment (ARCI). We aimed to assess the cognitive deficits in AUD patients with the help of a specific imaging marker for ARCI. Data-driven dynamic and static global signal topography (GST) methods were applied to explore the cross-talks between local and global neuronal activities in the AUD brain. Twenty-six ARCI, 54 AUD without cognitive impairment (AUD-NCI), and gender/age-matched 40 healthy control (HC) subjects were recruited for this study. We found that there was no significant difference with respect to voxel-based morphometry (VBM) and static GST between AUD-NCI and ARCI groups. And in dynamic GST measurements, the AUD-NCI patients had the highest coefficient of variation (CV) at the right insula, followed by ARCI and the HC subjects. In precuneus, the order was reversed. There was no significant correlation between the dynamic GST and behavioral scores or alcohol consumption. These results suggested that dynamic GST might have potential implications in understanding AUD pathogenesis and disease management.

The neurobiology of drug addiction: cross-species insights into the dysfunction and recovery of the prefrontal cortex

A growing preclinical and clinical body of work on the effects of chronic drug use and drug addiction has extended the scope of inquiry from the putative reward-related subcortical mechanisms to higher-order executive functions as regulated by the prefrontal cortex. Here we review the neuroimaging evidence in humans and non-human primates to demonstrate the involvement of the prefrontal cortex in emotional, cognitive, and behavioral alterations in drug addiction, with particular attention to the impaired response inhibition and salience attribution (iRISA) framework. In support of iRISA, functional and structural neuroimaging studies document a role for the prefrontal cortex in assigning excessive salience to drug over non-drug-related processes with concomitant lapses in self-control, and deficits in reward-related decision-making and insight into illness. Importantly, converging insights from human and non-human primate studies suggest a causal relationship between drug addiction and prefrontal insult, indicating that chronic drug use causes the prefrontal cortex damage that underlies iRISA while changes with abstinence and recovery with treatment suggest plasticity of these same brain regions and functions. We further dissect the overlapping and distinct characteristics of drug classes, potential biomarkers that inform vulnerability and resilience, and advancements in cutting-edge psychological and neuromodulatory treatment strategies, providing a comprehensive landscape of the human and non-human primate drug addiction literature as it relates to the prefrontal cortex.

Disentangling craving- and valence-related brain responses to smoking cues in individuals with nicotine use disorder

Tobacco smoking is one of the leading causes of preventable death and disease worldwide. Most smokers want to quit, but relapse rates are high. To improve current smoking cessation treatments, a better understanding of the underlying mechanisms of nicotine dependence and related craving behaviour is needed. Studies on cue‐driven cigarette craving have been a particularly useful tool for investigating the neural mechanisms of drug craving. Here, functional neuroimaging studies in humans have identified a core network of craving‐related brain responses to smoking cues that comprises of amygdala, anterior cingulate cortex, orbitofrontal cortex, posterior cingulate cortex and ventral striatum. However, most functional Magnetic Resonance Imaging (fMRI) cue‐reactivity studies do not adjust their stimuli for emotional valence, a factor assumed to confound craving‐related brain responses to smoking cues. Here, we investigated the influence of emotional valence on key addiction brain areas by disentangling craving‐ and valence‐related brain responses with parametric modulators in 32 smokers. For one of the suggested key regions for addiction, the amygdala, we observed significantly stronger brain responses to the valence aspect of the presented images than to the craving aspect. Our results emphasize the need for carefully selecting stimulus material for cue‐reactivity paradigms, in particular with respect to emotional valence. Further, they can help designing future research on teasing apart the diverse psychological dimensions that comprise nicotine dependence and, therefore, can lead to a more precise mapping of craving‐associated brain areas, an important step towards more tailored smoking cessation treatments.

An exploration of associations between smoking motives and behavior as a function of body mass index

Objective

Cigarette smoking and obesity are the leading causes of premature morbidity and mortality and increase the risk of all-cause mortality four-fold when comorbid. Although research suggests that smoking motives may differ based on body mass index (BMI), it is unclear how these differences translate to smoking behavior.

Method

Three groups of adults who smoke cigarettes (N = 79; obese n = 25, overweight n = 30, and lean n = 24) completed measures of smoking and the Smoking Motivations Questionnaire. Groups did not differ on age, education, cigarettes per day (CPD), pack-years, or nicotine dependence, as measured by the Fagerström Test for Cigarette Dependence (FTCD).

Results

Analyses revealed different associations between reasons for smoking and smoking behavior depending on lean, overweight, or obesity status. Participants (N = 37 female, average age 39.8 years) self-reported smoking was positively associated with Addictive, and Automatic subscale scores among lean participants, with only the Addictive subscale score among those with overweight, and only the Automatic subscale score among those with obesity. Post hoc MANCOVA analysis revealed a significant interaction effect of Group x Automatic Smoking on Pack-years (F(2, 79)=3.34, p = 0.04).

Conclusion

Findings suggest smoking motives are differentially associated with smoking behavior in adults who smoke depending on weight status. The daily smoking rate of participants with obesity may be less related to the addictive quality of smoking, and automaticity may be less associated with smoking history in those with overweight. Additional research on the influence of BMI on cigarette smoking is necessary to fully elucidate how obesity may impact treatment outcomes to optimize smoking cessation treatment among those with excess body weight.

Varenicline as a treatment for cannabis use disorder: A placebo-controlled pilot trial

BACKGROUND

An efficacious pharmacotherapy for cannabis use disorder (CUD) has yet to be established. This study preliminarily evaluated the safety and efficacy of varenicline for CUD in a proof-of-concept clinical trial.

METHODS

Participants in this 6-week randomized, placebo-controlled pilot trial received either varenicline (n = 35) or placebo (n = 37), added to a brief motivational enhancement therapy intervention. Outcomes included cannabis withdrawal, cannabis abstinence, urine cannabinoid levels, percent cannabis use days, and cannabis sessions per day.

RESULTS

Both treatment groups noted significant decreases in self-reported cannabis withdrawal, percentage of days used, and use sessions per day during treatment compared to baseline. While this pilot trial was not powered to detect statistically significant between-group differences, participants randomized to varenicline evidenced numerically greater rates of self-reported abstinence at the final study visit [Week 6 intent-to-treat (ITT): Varenicline: 17.1% vs. Placebo: 5.4%; RR = 3.2 (95% CI: 0.7,14.7)]. End-of-treatment urine creatinine corrected cannabinoid levels were numerically lower in the varenicline group and higher in the placebo group compared to baseline [Change from baseline: Varenicline -1.7 ng/mg (95% CI: -4.1,0.8) vs. Placebo: 1.9 ng/mg (95% CI: -0.4,4.3); Δ = 3.5 (95% CI: 0.1,6.9)]. Adverse events related to study treatment did not reveal new safety signals.

CONCLUSIONS

Findings support the feasibility of conducting clinical trials of varenicline as a candidate pharmacotherapy for CUD, and indicate that a full-scale efficacy trial, powered based on effect sizes and variability yielded in this study, is warranted.

Exploration of the influence of body mass index on intra-network resting-state connectivity in chronic cigarette smokers

BACKGROUND

Obesity and cigarette smoking are two leading preventable causes of death. Previous research suggests that comorbid smoking and obesity likely share neurobehavioral underpinnings; however, the influence of body mass index (BMI) on resting-state functional connectivity (rsFC) in smokers remains unknown. In this study, we explore how BMI affects rsFC and associations between rsFC and smoking-related behavior.

METHODS

Treatment-seeking cigarette smokers (N = 87; 54 % men) completed a BOLD resting-state fMRI scan session. We grouped smokers into BMI groups (N = 23 with obesity, N = 33 with overweight, N = 31 lean) and used independent components analysis (ICA) to identify the resting state networks commonly associated with cigarette smoking: salience network (SN), right and left executive control networks (ECN) and default mode network (DMN). Average rsFC values were extracted (p < 0.001, k = 100) to determine group differences in rsFC and relationship to self-reported smoking and dependence.

RESULTS

Analyses revealed a significant relationship between BMI and connectivity in the SN and a significant quadratic effect of BMI on DMN connectivity. Heavier smoking was related to greater rsFC in the SN among lean and obese groups but reduced rsFC in the overweight group.

CONCLUSIONS

Findings build on research suggesting an influence of BMI on the neurobiology of smokers. In particular, dysfunction of SN-DMN-ECN circuitry in smokers with overweight may lead to a failure to modulate attention and behavior and subsequent difficulty quitting smoking. Future research is needed to elucidate the mechanism underlying the interaction of BMI and smoking and its impact on treatment.

Combined varenicline and naltrexone attenuates alcohol cue-elicited activation in heavy drinking smokers

BACKGROUND

There is a strong bidirectional relationship between the use of alcohol and cigarettes which results in various challenges for treating those who co-use both substances. While varenicline and naltrexone each have FDA-approval for nicotine and alcohol use disorder, respectively, there is evidence that their clinical benefit may extend across the two disorders. Critically, the effect of combined varenicline and naltrexone on neural reactivity to alcohol cues among heavy drinking smokers has not yet been studied. Probing the effect of the combination therapy on alcohol cue-reactivity may give insight to the mechanisms underlying its efficacy.

METHODS

Forty-seven heavy drinking smokers enrolled in two medication studies were randomized to receive varenicline alone (n = 11), varenicline plus naltrexone (n = 11), or placebo (n = 25). Participants completed an fMRI alcohol cue-reactivity task and rated their in-scanner alcohol craving. Whole-brain analyses examined the effect of medication on alcohol cue-elicited neural response.

RESULTS

Varenicline plus naltrexone attenuated alcohol cue-elicited activation in mesolimbic regions relative to varenicline alone and to placebo (Z > 2.3, p < 0.05). The combination varenicline and naltrexone group also endorsed lower in-scanner alcohol craving relative to varenicline alone group (p = 0.04).

CONCLUSIONS

These findings provide evidence for the benefit of combined therapy of varenicline and naltrexone over varenicline alone for the attenuation of alcohol cue-elicited neural activation. This study provides a preliminary proof-of-mechanism for this combination pharmacotherapy and suggests that naltrexone may be driving the reductions in cue-elicited alcohol craving in the brain. Further clinical studies using the combined therapy to treat heavy drinking smokers are warranted.

Disrupted prefrontal regulation of striatum-related craving in Internet gaming disorder revealed by dynamic causal modeling: results from a cue-reactivity task

BACKGROUND

Studies of Internet gaming disorder (IGD) suggest an imbalanced relationship between cognitive control and reward processing in people with IGD. However, it remains unclear how these two systems interact with each other, and whether they could serve as neurobiological markers for IGD.

METHODS

Fifty IGD subjects and matched individuals with recreational game use (RGU) were selected and compared when they were performing a cue-craving task. Regions of interests [anterior cingulate cortex (ACC), lentiform nucleus] were selected based on the comparison between brain responses to gaming-related cues and neutral cues. Directional connectivities among these brain regions were determined using Bayesian estimation. We additionally examined the posterior cingulate cortex (PCC) in a separate analysis based on data implicating the PCC in craving in addiction.

RESULTS

During fixed-connectivity analyses, IGD subjects showed blunted ACC-to-lentiform and lentiform-to-ACC connectivity relative to RGU subjects, especially in the left hemisphere. When facing gaming cues, IGD subjects trended toward lower left-hemispheric modulatory effects in ACC-to-lentiform connectivity than RGU subjects. Self-reported cue-related craving prior to scanning correlated inversely with left-hemispheric modulatory effects in ACC-to-lentiform connectivity.

CONCLUSIONS

The results suggesting that prefrontal-to-lentiform connectivity is impaired in IGD provides a possible neurobiological mechanism for difficulties in controlling gaming-cue-elicited cravings. Reduced connectivity ACC-lentiform connectivity may be a useful neurobiological marker for IGD.

Smoking Treatment: A Report Card on Progress and Challenges

The impact of tobacco smoking treatment is determined by its reach into the smoking population and the effectiveness of its interventions. This review evaluates the reach and effectiveness of pharmacotherapy and psychosocial interventions for smoking. Historically, the reach of smoking treatment has been low, and therefore its impact has been limited, but new reach strategies such as digital interventions and health care system changes offer great promise. Pharmacotherapy tends to be more effective than psychosocial intervention when used clinically, and newer pharmacotherapy strategies hold great promise of further enhancing effectiveness. However, new approaches are needed to advance psychosocial interventions; progress has stagnated because research and dissemination efforts have focused too narrowly on skill training despite evidence that its core content may be inconsequential and the fact that its mechanisms are either unknown or inconsistent with supporting theory. Identifying effective psychosocial content and its mechanisms of action could greatly enhance the effectiveness of counseling, digital, and web interventions.

Smoking-induced craving relief relates to increased DLPFC-striatal coupling in nicotine-dependent women

BACKGROUND

Craving is a major contributor to drug-seeking and relapse. Although the ventral striatum (VS) is a primary neural correlate of craving, strategies aimed at manipulating VS function have not resulted in efficacious treatments. This incongruity may be because the VS does not influence craving in isolation. Instead, craving is likely mediated by communication between the VS and other neural substrates. Thus, we examined how striatal functional connectivity (FC) with key nodes of networks involved in addiction affects relief of craving, which is an important step in identifying viable treatment targets.

METHODS

Twenty-four nicotine-dependent non-abstinent women completed two resting-state (rs) fMRI scans, one before and one following smoking a cigarette in the scanner, and provided craving ratings before and after smoking the cigarette. A seed-based approach was used to examine rsFC between the VS, putamen and germane craving-related brain regions; the dorsolateral prefrontal cortex (dlPFC), the posterior cingulate cortex, and the anterior ventral insula.

RESULTS

Smoking a cigarette was associated with a decrease in craving. Relief of craving correlated with increases in right dlPFC- bilateral VS (r = 0.57, p = 0.003, corrected) as did increased right dlPFC-left putamen coupling (r = 0.62, p = 0.001, corrected).

CONCLUSIONS

Smoking-induced relief of craving is associated with enhanced rsFC between the dlPFC, a region that plays a pivotal role in decision making, and the striatum, the neural structure underlying motivated behavior. These findings are highly consistent with a burgeoning literature implicating dlPFC-striatal interactions as a neurobiological substrate of craving.

Significant association of nicotine reinforcement and cue reactivity: a translational study in humans and rats

Relapse is common amongst smokers attempting to quit and tobacco cue-induced craving is an important relapse mechanism. Preclinical studies commonly use cue-induced reinstatement of nicotine seeking to investigate relapse neurobiology. Previous research suggests dependence severity and nicotine intake history affect smoking resumption and cue-induced reinstatement of nicotine seeking. However, behavioural data may be interpreted in terms of nicotine reinforcement. This translational study investigated if individual differences in objectively assessed nicotine reinforcement strength were associated with cue-reactivity in both rats and human smokers, which to our knowledge has not been investigated before. Rats (n = 16) were trained to self-administer nicotine and were tested on a progressive ratio schedule of nicotine reinforcement, to assess reinforcer strength, and on a test of cue-induced reinstatement of nicotine seeking. Nicotine reinforcement strength was assessed in human smokers (n = 104) using a forced choice task (nicotine containing vs. denicotinised cigarettes) and self-reported cue-induced craving was assessed following exposure to smoking and neutral cues. Responding for nicotine under progressive ratio was strongly positively correlated with cue-induced reinstatement of nicotine seeking in rats. Nicotine choices in human smokers were significantly associated with cue-induced craving controlling for dependence severity, years of smoking, and urge to smoke following neutral cues. Findings suggest nicotine reinforcement strength is associated with both types of cue-induced behaviour, implying some translational commonality between cue-induced craving in human smokers and cue-induced reinstatement of nicotine seeking in rats. Findings are discussed in relation to clinical implications and whether these laboratory tasks assess drug 'wanting'.

The CB1R rs2023239 receptor gene variant significantly affects the reinforcing effects of nicotine, but not cue reactivity, in human smokers

INTRODUCTION

The cannabinoid CB1 receptor (CB1R) has been shown in preclinical studies to be involved in nicotine reinforcement and relapse-like behavior. The common single nucleotide polymorphism (SNP) rs2023239 may code for an alternative CB1R protein, alter CB1R expression, and be involved in nicotine dependence. To date, no study has explored the relationship between this SNP in CB1R and specific phenotypes of nicotine dependence.

METHODS

The current study investigated the influence of CB1R rs2023239 in nicotine reinforcement and craving in regular cigarette smokers. Current smokers (n = 104, cigarettes per day ≥ 10) were genetically grouped (C allele group vs. No C allele group) and underwent laboratory measures of nicotine reinforcement and smoking cue-elicited craving. Nicotine reinforcement was assessed using a forced choice paradigm, while a cue-reactivity procedure measured cue-elicited craving.

RESULTS

These results show that smokers with the C allele variant (CC + CT genotypes) experienced a lower nicotine reinforcement effect compared to those without the C allele (TT genotype). These results were similar in both our subjective and behavioral reinforcement measures, though the subjective effects did not withstand controlling for race. There was no difference between genotype groups with respect to cue-elicited craving, suggesting a lack of influence in cue reactivity.

CONCLUSION

Taken together, these results suggest that the variation in the CB1R (i.e., rs2023239 SNP) may play a larger role in nicotine reinforcement compared to cue reactivity. This work provides impetus to further understand the physiological mechanisms that explain how CB1Rs influence nicotine dependence phenotypes.

The impact of three weeks of pre-quit varenicline on reinforcing value and craving for cigarettes in a laboratory choice procedure

RATIONALE

Varenicline, a partial nicotinic agonist, is theorized to attenuate pre-quit smoking reinforcement and post-quit withdrawal and craving. However, the mechanisms of action have not been fully characterized, as most studies employ only retrospective self-report measures, hypothetical indices of reinforcing value, and/or nontreatment-seeking samples.

OBJECTIVES

The current research examined the impact of pre-quit varenicline (vs. placebo) on laboratory measures of smoking and food (vs. water) reinforcement and craving.

METHODS

Participants were 162 treatment-seeking smokers enrolled in a randomized controlled trial of smoking cessation ( clinicaltrials.gov ID: NCT03262662). Participants completed two laboratory sessions: a pre-treatment session, ~ 1 week prior to beginning varenicline or placebo, and an active treatment session, after ~ 3 weeks of treatment. At each session, participants completed a laboratory choice procedure; on each of 36 trials, a lit cigarette, food item, or cup of water was randomly presented. Participants reported level of craving and spent $0.01-0.25 to have a corresponding 5-95% chance to sample the cue.

RESULTS

As predicted, spending was significantly higher on cigarette trials than water trials, and varenicline resulted in a greater between-session decline in spending on cigarette trials (but not water) than did placebo. Cigarette craving was enhanced in the presence of smoking cues compared to water, but neither average (tonic) cigarette craving nor cue-specific cigarette craving was significantly influenced by varenicline. Food spending and craving were generally unaffected by varenicline treatment.

CONCLUSIONS

These laboratory data from treatment-seeking smokers provide the strongest evidence to date that varenicline selectively attenuates smoking reinforcement prior to quitting.

Baclofen-induced Changes in the Resting Brain Modulate Smoking Cue Reactivity: A Double-blind Placebo-controlled Functional Magnetic Resonance Imaging Study in Cigarette Smokers

Objective

Smoking cue-(SC) elicited craving can lead to relapse in SC-vulnerable individuals. Thus, identifying treatments that target SC-elicited craving is a top research priority. Reduced drug cue neural activity is associated with recovery and is marked by a profile of greater tonic (resting) activation in executive control regions, and increased connectivity between executive and salience regions. Evidence suggests the GABA-B agonist baclofen can reduce drug cue-elicited neural activity, potentially through its actions on the resting brain. Based on the literature, we hypothesize that baclofen’s effects in the resting brain can predict its effects during SC exposure.

Methods

In this longitudinal, double blind, placebo-controlled neuropharmacological study 43 non-abstinent, sated treatment-seeking cigarette smokers (63% male) participated in an fMRI resting-state scan and a SC-reactivity task prior to (T1) and 3 weeks following randomization (T2; baclofen: 80 mg/day; n = 21). Subjective craving reports were acquired before and after SC exposure to explicitly examine SC-induced craving.

Results

Whole-brain full-factorial analysis revealed a group-by-time interaction with greater resting brain activation of the right dorsolateral prefrontal cortex (dlPFC) at T2 in the baclofen group (BAC) (p_FWEcorr = 0.02), which was associated with reduced neural responses to SCs in key cue-reactive brain regions; the anterior ventral insula and ventromedial prefrontal cortex (p_FWEcorr < 0.01). BAC, but not the placebo group reported decreased SC-elicited craving (p = 0.02).

Conclusion

Results suggest that baclofen mitigates the reward response to SCs through an increase in tonic activation of the dlPFC, an executive control region. Through these mechanisms, baclofen may offer SC-vulnerable smokers protection from SC-induced relapse.

Brain Responses to Cigarette-Related and Emotional Images in Smokers During Smoking Cessation: No Effect of Varenicline or Bupropion on the Late Positive Potential

Introduction

Varenicline and bupropion are two effective smoking cessation pharmacotherapies. Researchers have hypothesized that they might be effective, in part, because they reduce cue reactivity and cue-induced cravings. Here, we used event-related potentials (ERPs) to directly measure brain responses to cigarette-related and other motivationally relevant images during a pharmacologically aided quit attempt.

Methods

Smokers involved in a 12-week placebo-controlled double-blind clinical trial of smoking cessation medications (varenicline, bupropion, placebo) took part in the study. We assessed participants at two time points: 24 h (n = 140) and 4 weeks (n = 176) after the quit date. At both sessions, we measured the amplitude of the late positive potential (LPP), an ERP component reliably associated with motivational relevance, and self-reported tonic craving using the brief version of the Questionnaire of Smoking Urges (QSU-Brief).

Results

At both sessions, emotional and cigarette-related images evoked significantly larger LPPs than neutral images. Neither drug type nor smoking abstinence altered this effect at either session. At both sessions, varenicline and bupropion significantly reduced self-reported tonic craving relative to the placebo condition.

Conclusions

While both varenicline and bupropion reduced self-reported tonic craving, neither medication altered the amplitude of the LPP to cigarette-related or emotional pictures in smokers attempting to quit. These medications may influence abstinence by means other than by reducing neuroaffective responses to cigarette-related cues. Smokers should be prepared for the likelihood that even after several weeks of successful abstinence, once treatment ends, cigarette-related cues may remain motivationally relevant and trigger cravings that might lead to relapse.

Implications

Bupropion and varenicline do not alter electrophysiological responses, as measured by the LPP, to cigarette-related and emotional images. These findings help explain why cigarette-related cues can trigger relapse when smoking cessation medication treatments end.

A Preliminary Examination of Nicotine-Free Electronic Cigarette Use During Cessation From Combustible Cigarettes

Despite the availability of smoking cessation strategies, smoking cue-induced craving remains a relatively untreated relapse risk factor. Utilizing nicotine-free electronic cigarettes (e-cigarettes) to extinguish the motivational influence of smoking cues may be a viable approach to address cue reactivity. In this pilot study, 26 daily tobacco smokers used nicotine-free e-cigarettes while being maintained on daily transdermal sustained-release nicotine replacement therapy (NRT) to mitigate pharmacological withdrawal. Sensitivity to cue-induced craving, measured by the rise in craving after a visual cue exposure task, was assessed at a baseline visit after smoking as usual and again after 2 weeks of nicotine-free e-cigarette and NRT use. Participants' pattern and amount of tobacco cigarette smoking were evaluated on both visits and 1 month posttreatment. Cue-induced craving significantly decreased after the 2-week intervention, yet withdrawal scores increased during this time. One month after study completion, participants continued to report significantly lower overall cigarette craving and conventional tobacco cigarette use. Including the 34.8% that were totally abstinent, 65.2% reported smoking fewer than 10 cigarettes per week (compared to 87.2 per week at baseline for the entire group). A linear regression revealed that greater baseline cue-induced craving predicted better outcomes, whereas more withdrawal at the e-cigarette visit was related to more smoking at 1 month. This proof-of-concept pilot study suggests that the addition of ad libitum nicotine-free e-cigarettes to an existing strategy of transdermal NRT may attenuate cue-induced craving for tobacco smoking. A larger sample that is powered for detecting additional factors and longer-term outcomes is warranted.

Nicotine Self-Administration as Paradigm for Medication Discovery for Smoking Cessation: Recent Findings in Medications Targeting the Cholinergic System

Tobacco kills every year approximately six million people as a direct result of direct use, and it is still considered one of the most excruciating threats for human health worldwide. The low successful rates of the currently available pharmacotherapies to assist in quitting tobacco use suggest there is a need for more effective treatments.The intravenous self-administration (IVSA) paradigm is considered the gold standard to study voluntary drug intake in animal models, including nicotine. The IVSA paradigm has been used to identify key mechanisms involved in the addictive properties of nicotine in both rodents and nonhuman primates. In this chapter we describe how the IVSA paradigm has served to further investigate the role of nicotinic acetylcholine receptors (nAChRs) in the reinforcing properties of nicotine. Notably, this review will cover recent advances (i.e., research carried out during the past decade) using the IVSA paradigm, with a focus on the status of research on current smoking cessation medications (such as varenicline and bupropion) and of other nAChR ligands.The combination of the IVSA paradigm with pharmacological and genetic tools (e.g., knockout animals) has greatly contributed to our understanding of the role of specific subtype nAChRs in nicotine reinforcement processes. We also discuss some of the limitations of the IVSA paradigm so these can be taken into consideration when interpreting and designing new studies.

Anterior insula activity regulates the associated behaviors of high fat food binge intake and cue reactivity in male rats

Binge eating episodes are characterized by uncontrollable, excessive intake of food and are associated with binge eating disorder and some subtypes of obesity. One factor thought to contribute to binge episodes is a high level of reactivity to food-associated cues (i.e., cue reactivity). The insula is a neural node poised to regulate both binge eating and cue reactivity because of its prominent role in interpretation of internal and external cues. This work established a positive association between high fat food (HFF) binge intake and cue reactivity in male rats. Furthermore, we demonstrated that activation of the anterior insula suppressed both HFF binge intake and cue reactivity, without altering homeostatic intake of food. We further show that attenuation of HFF binge intake and cue reactivity is not due to decreased food-reward efficacy or deficits in motivation. Together, these data establish a key role for the anterior insula in the control of binge eating related-behaviors and support novel avenues for the treatment of binge eating.

Functional brain activation changes associated with practice in delaying smoking among moderate to heavy smokers: study protocol and rationale of a randomized trial (COPE)

BACKGROUND

Most smokers struggle to overcome tobacco addiction. Neuroscientific models of addiction emphasize the importance of brain regions associated with cognitive control and reward to understand the cycle of addiction and relapse. During an attempt at abstinence, the cognitive control system appears to be underpowered to override the heightened reward system of the addicted brain. Thus, one neural target for treatment is to strengthen the cognitive control system. It may be possible to improve the functioning of the cognitive control system via deliberate practice.

METHODS/DESIGN

This study will determine the effects of practicing delaying smoking on brain and behavioral measures of cognitive control. Smoking patterns will be monitored for 1 week and then smokers (N = 80) will be randomized to either practice cognitive control by delaying their first cigarette of the day for 2 weeks (practice group) or they will continue monitoring only (no practice group). Functional magnetic resonance imaging will be performed while smokers regulate their responses to smoking images (i) at baseline and (ii) after 2 weeks of practice (or no practice).

DISCUSSION

The primary aim of this study will be to identify the impact of practicing cognitive control on functional brain activation changes in response to smoking cues. If successful, this project will establish a neurobiological biomarker for increasing cognitive control and demonstrate the feasibility of neuroimaging methods to predict the efficacy of an intervention without a large clinical trial.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03080844 . Registered March 15, 2017.

Distress Tolerance and Craving for Cigarettes Among Heavy Drinking Smokers

OBJECTIVE

Heavy drinking smokers experience significant difficulties with smoking cessation. Craving is closely tied to relapses during cessation attempts, and alcohol consumption increases cigarette craving among heavy drinking smokers. To date, however, few moderators of the relationship between craving and relapse have been identified. Individuals' capacity for distress tolerance predicts smoking cessation outcomes and may be connected to craving. Relatedly, pharmacotherapies like varenicline and naltrexone reduce cigarette and alcohol cravings, respectively. No studies have examined the interrelationships among distress tolerance, craving, and pharmacotherapy effects. This study therefore examines distress tolerance as a moderator of the relationship between overnight abstinence-induced cigarette craving and subsequent alcohol- and cigarette-induced changes in craving among heavy drinking smokers. This study also examines the impact of varenicline and naltrexone on these relationships.

METHOD

A total of 120 non-treatment-seeking heavy drinking smokers were randomized and titrated to one of the following conditions: (a) placebo, (b) varenicline, (c) naltrexone, or (d) varenicline + naltrexone. Participants then completed a laboratory paradigm after overnight abstinence that included consumption of alcohol (target .06 g/dl breath alcohol concentration) and one cigarette. Craving was assessed as abstinence-induced (Time 1), alcohol-induced (Time 2), and cigarette-induced (Time 3).

RESULTS

Within varenicline + naltrexone, low distress tolerance individuals exhibited higher increases from abstinence- to alcohol-induced cigarette craving relative to high distress tolerance individuals. Across medications, low distress tolerance individuals reported flatter decreases from abstinence- to cigarette-induced cigarette craving relative to high distress tolerance individuals.

CONCLUSIONS

Distress tolerance may differentially predict alcohol-induced cigarette craving when titrated to pharmacotherapy, as well as moderate decreases in craving after cigarette consumption. Future exploration of the identified interactive effects could elucidate specific conditions in which cravings are more proximally related to abstinence-induced smoking.

Distress Tolerance and Craving for Cigarettes Among Heavy Drinking Smokers

OBJECTIVE

Heavy drinking smokers experience significant difficulties with smoking cessation. Craving is closely tied to relapses during cessation attempts, and alcohol consumption increases cigarette craving among heavy drinking smokers. To date, however, few moderators of the relationship between craving and relapse have been identified. Individuals' capacity for distress tolerance predicts smoking cessation outcomes and may be connected to craving. Relatedly, pharmacotherapies like varenicline and naltrexone reduce cigarette and alcohol cravings, respectively. No studies have examined the interrelationships among distress tolerance, craving, and pharmacotherapy effects. This study therefore examines distress tolerance as a moderator of the relationship between overnight abstinence-induced cigarette craving and subsequent alcohol- and cigarette-induced changes in craving among heavy drinking smokers. This study also examines the impact of varenicline and naltrexone on these relationships.

METHOD

A total of 120 non-treatment-seeking heavy drinking smokers were randomized and titrated to one of the following conditions: (a) placebo, (b) varenicline, (c) naltrexone, or (d) varenicline + naltrexone. Participants then completed a laboratory paradigm after overnight abstinence that included consumption of alcohol (target .06 g/dl breath alcohol concentration) and one cigarette. Craving was assessed as abstinence-induced (Time 1), alcohol-induced (Time 2), and cigarette-induced (Time 3).

RESULTS

Within varenicline + naltrexone, low distress tolerance individuals exhibited higher increases from abstinence- to alcohol-induced cigarette craving relative to high distress tolerance individuals. Across medications, low distress tolerance individuals reported flatter decreases from abstinence- to cigarette-induced cigarette craving relative to high distress tolerance individuals.

CONCLUSIONS

Distress tolerance may differentially predict alcohol-induced cigarette craving when titrated to pharmacotherapy, as well as moderate decreases in craving after cigarette consumption. Future exploration of the identified interactive effects could elucidate specific conditions in which cravings are more proximally related to abstinence-induced smoking.

Smoking Cessation With 20 Hz Repetitive Transcranial Magnetic Stimulation (rTMS) Applied to Two Brain Regions: A Pilot Study

Chronic smoking impairs brain functions in the prefrontal cortex and the projecting meso-cortical limbic system. The purpose of this pilot study is to examine whether modulating the frontal brain activity using high-frequency repetitive transcranial magnetic stimulation (rTMS) can improve smoking cessation and to explore the changing pattern of the brain activity after treatment. Fourteen treatment-seeking smokers were offered a program involving 10 days of rTMS treatment with a follow-up for another 25 days. A frequency of 20 Hz rTMS was sequentially applied on the left dorso-lateral prefrontal cortex (DLPFC) and the superior medial frontal cortex (SMFC). The carbon monoxide (CO) level, withdrawal, craving scales, and neuroimaging data were collected. Ten smokers completed the entire treatment program, and 90% of them did not smoke during the 25-day follow-up time. A significant smoking craving reduction and resting brain activity reduction measured by the cerebral blood flow (CBF) and brain entropy (BEN) were observed after 10 days of 20 Hz rTMS treatments compared to the baseline. Although limited by sample size, these pilot findings definitely showed a high potential of multiple-target high-frequency rTMS in smoking cessation and the utility of fMRI for objectively assessing the treatment effects.

Discovery and development of varenicline for smoking cessation

INTRODUCTION

Tobacco use causes one premature death every six seconds. Current smoking cessation aids include nicotine replacement therapies, bupropion, and varenicline. Although more than 70% of smokers express a desire to quit, fewer than 3% remain abstinent for more than one year, highlighting a critical need for more efficacious smoking cessation treatments. Areas covered: The authors discuss the rationale, preclinical and clinical development of varenicline for smoking cessation. They cover the development of varenicline as a partial agonist at α4β2 receptors, the primary neural substrate for nicotine reward. Then, they discuss evidence from preclinical studies indicating varenicline's efficacy in blocking nicotine reward, followed by clinical trials demonstrating safety and efficacy in sustaining abstinence in smokers. Finally, they cover post-market surveillance, including caution in heavy machine operators, putative cardiovascular risk, and the repealed warning for adverse neuropsychiatric events. Expert opinion: Varenicline development was based on strong theoretical rationale and preclinical evidence. Clinical studies indicate that varenicline is safe and more effective in sustaining abstinence than placebo, bupropion or nicotine replacement therapies. However, given that continuous abstinence rates across studies remain low (18 ~ 30% with varenicline; 4 ~ 10% with placebo), novel and more effective medications targeting other nicotinic or glutamate receptors for smoking cessation are required.

Default mode network deactivation to smoking cue relative to food cue predicts treatment outcome in nicotine use disorder

Identifying predictors of treatment outcome for nicotine use disorders (NUDs) may help improve efficacy of established treatments, like varenicline. Brain reactivity to drug stimuli predicts relapse risk in nicotine and other substance use disorders in some studies. Activity in the default mode network (DMN) is affected by drug cues and other palatable cues, but its clinical significance is unclear. In this study, 143 individuals with NUD (male n = 91, ages 18-55 years) received a functional magnetic resonance imaging scan during a visual cue task during which they were presented with a series of smoking-related or food-related video clips prior to randomization to treatment with varenicline (n = 80) or placebo. Group independent components analysis was utilized to isolate the DMN, and temporal sorting was used to calculate the difference between the DMN blood-oxygen-level dependent signal during smoke cues and that during food cues for each individual. Food cues were associated with greater deactivation compared with smoke cues in the DMN. In correcting for baseline smoking and other clinical variables, which have been shown to be related to treatment outcome in previous work, a less positive Smoke - Food difference score predicted greater smoking at 6 and 12 weeks when both treatment groups were combined (P = 0.005, β = -0.766). An exploratory analysis of executive control and salience networks demonstrated that a more positive Smoke - Food difference score for executive control network predicted a more robust response to varenicline relative to placebo. These findings provide further support to theories that brain reactivity to palatable cues, and in particular in DMN, may have a direct clinical relevance in NUD.

Pharmacological intervention and abstinence in smokers undergoing cessation treatment: A psychophysiological study

As a composite concept, negative affect comprises various aversive emotional experiences, such as irritability and nervousness. It is a critical motivational factor that helps maintain smoking behavior, and contributes significantly to smoking cessation failure as a core withdrawal symptom. Prior research has indicated an important role of nicotinic mechanisms in negative affect processing. The most effective smoking cessation medication, varenicline, targets nicotinic acetylcholine receptors (nAChRs) as a partial agonist, while another first-line cessation medication, bupropion, has shown antagonistic effects on nAChRs. Therefore, it is possible that both medications work to reduce smoking behavior through modulating negative affect processing. To evaluate this hypothesis, we examined the impact of varenicline tartrate and bupropion hydrochloride sustained-release on electrophysiological responses to affective, cigarette-related, and neutral cues before and during smoking cessation treatment in a randomized placebo-controlled clinical trial. The participants were 206 smokers, a subset of 294 participants that were enrolled in a larger smoking cessation clinical trial who were randomly assigned to one medication group for 12weeks. Orbicularis oculi (startle eyeblink response) and corrugator supercilii facial electromyographic (EMG) reactivity toward emotional pictures (i.e., pleasant and unpleasant) in a picture-viewing task were measured before treatment and 2 and 6weeks after treatment was started. The startle and corrugator EMG activities increase with the exposure to unpleasant cues, and served as indices for negative emotional reactivity (NER). We found that after 6weeks, drug reduced startle-related NER in the varenicline group, but not in the bupropion or placebo group. Independent of medication treatment, lower baseline NER, as measured by the corrugator EMG activity, predicted a higher likelihood of smoking abstinence 1 and 3months after quitting smoking. These findings indicate the important roles of varenicline in negative affect processing and negative emotional reactivity in the course of smoking cessation.

Brain substrates of early (4h) cigarette abstinence: Identification of treatment targets

INTRODUCTION

Research indicates that overnight nicotine abstinence disrupts neural activity in the mesocorticolimbic reward network; however, less is known about the time course of abstinence-induced brain changes. To examine the potential neural effects of early abstinence, we used arterial spin labeling perfusion fMRI, to measure regional cerebral blood flow (rCBF) changes in the resting brain induced by 4h of nicotine abstinence.

METHODS

In a repeated measures design, 5min of resting perfusion fMRI data were acquired in awake nicotine-dependent individuals (eyes open) during 'smoking as usual' (SMK) and following 4h of monitored nicotine abstinence (ABS) conditions (N=20). Conditions were compared using a paired t test in SPM8. Craving was assessed prior to each condition.

RESULTS

Compared to SMK, ABS significantly increased craving and reduced rCBF in select regions, including the hippocampus and ventral striatum (cluster corr, α=0.01, 943 contiguous voxels). The magnitude of the abstinence-induced change in rCBF correlated with the magnitude of the change in craving across conditions in select regions, including the medial and lateral orbitofrontal cortices and the anterior ventral insula (r values ranging from 0.59-0.74).

CONCLUSIONS

Results show that as few as 4h of abstinence can reduce resting rCBF in multiple nodes of the brain's mesocorticolimbic network, disrupting neural processing. Identifying early withdrawal treatment targets has far-reaching implications, which include thwarting relapse proclivities. Results parallel those of the extant human literature and are in agreement with an extensive preclinical literature showing compromised mesolimbic dopaminergic function and impairments in reward function during nicotine withdrawal.

Progesterone for smoking relapse prevention following delivery: A pilot, randomized, double-blind study

INTRODUCTION

Close to half of women who were smokers prior to conception quit smoking in pregnancy, when endogenous progesterone levels are high. However, at least half resume pre-pregnancy smoking levels within weeks after delivery and when progesterone levels drop. The current pilot study tested the feasibility and preliminary efficacy of postpartum progesterone replacement in preventing relapse to smoking in postpartum women with a history of pre-pregnancy smoking.

METHODS

This was an 8-week, double-blind, parallel, randomized, placebo-controlled pilot trial of 41 women with a history of pre-pregnancy smoking who achieved abstinence by 32 weeks of gestation. Immediately following delivery women were randomized to oral micronized progesterone (200mg twice daily) or placebo via computerized urn randomization program. The main outcome measures were descriptions of study feasibility: recruitment and retention. Secondary outcomes were 7-day point prevalence of abstinence at week 8, time to relapse and smoking cravings.

RESULTS

The trial was feasible with adequate randomization, 64% (41/64) of eligible women, and trial retention, 78% (32/41) completed the trial. Women taking progesterone were 1.8 times more likely to be abstinent during week 8 and took longer to relapse (10 vs. 4 weeks) compared to the placebo group, although these differences did not reach statistical significance. After adjusting for age and pre-quit smoking level, the number needed to treat was 7. There was a 10% greater decline per week in craving ratings in the progesterone group compared to placebo (β=-0.10, 95% CI: -0.15, -0.04, p<0.01). No serious adverse events occurred during the trial.

CONCLUSIONS

These preliminary findings support the promise of progesterone treatment in postpartum smokers and could constitute a therapeutic breakthrough.If these preliminary findings can be evaluated and replicated in a larger study with sufficient power, this may constitute an acceptable and safe smoking relapse prevention strategy for use during lactation.

Altered function but not structure of the amygdala in nicotine-dependent individuals

Tobacco use disorder is frequently comorbid with emotional disorders, each exerting reciprocal influence on the other. As an important hub for emotional processing, amygdala may also play a critical role in tobacco addiction. Therefore, we aimed to investigate the volume and spontaneous activity of the amygdala in nicotine-dependent individuals and their relationships with cigarette use. A total of 84 smokers (aged 22-54 years) and 41 nonsmokers (aged 26-56 years) were enrolled in the present study. 3D-T1 weighted images and resting-state fMRI images were acquired from all participants. We used ROI-wise volume, fractional amplitude of low frequency fluctuation (fALFF) and resting-state functional connectivity (FC) to assess structural and functional changes of the amygdala in the smokers. There was no significant difference between smokers and nonsmokers on amygdala volume (p > 0.05). When compared to nonsmokers, increased fALFF in the right amygdala was observed in smokers (p = 0.024). In addition, increased FC between the left amygdala and the right precuneus and decreased FC between the right amygdala and the right orbitofrontal cortex (OFC) was found in smokers. In smokers, these amygdala measures did not correlate with any measures of cigarette use. The results revealed that the amygdala function but not volume was affected in nicotine addiction. When considering the fALFF and FC results, we propose that the OFC top-down control may regulate the amygdala activity in nicotine addicts. The pattern of amygdala-based FC in smokers revealed in our study may provide new information about the brain circuitry of tobacco dependence.

Sex Differences in Smoking Cessation Pharmacotherapy Comparative Efficacy: A Network Meta-analysis

Introduction

Converging clinical and biological evidence suggest sex is an important factor when selecting a pharmacological intervention for smoking cessation. The current investigation used network meta-analyses to estimate sex differences in the comparative efficacy of transdermal nicotine (TN), varenicline, and sustained release (SR) bupropion for smoking cessation.

Methods

Systematically searched previously published reviews and databases (Medline, PsycINFO, Embase) of randomized, double-blind, placebo-controlled trials of bupropion-SR, TN, and varenicline for cigarette smoking cessation in primary care/general community samples were included.

Results

Thirty-two studies met all criteria and 28 (88%) were included in the final analyses, representing 14 389 smokers (51% female). Results of the full sample (women and men combined) mirrored those from a Cochrane Tobacco Addiction Group network meta-analysis of smoking cessation pharmacotherapy, showing VAR>TN=BUP. All medications improved quit rates over placebo for both women and men. Relative to placebo, varenicline efficacy was similar for women and men. Significant sex differences were evident when comparing varenicline versus TN and varenicline versus bupropion. For women, varenicline was more efficacious than TN (RR = 1.41; 95% CI = 1.12,1.76) and bupropion (RR = 1.38; 95% CI = 1.08,1.77). For men, outcomes for those treated with TN and bupropion were similar to those treated with varenicline. There were no differences in efficacy when comparing bupropion versus TN.

Conclusions

The advantage of varenicline over bupropion SR and TN is greater for women than men. Clinicians should strongly consider varenicline as the first option treatment for women. Among men, the advantage of varenicline over TN or bupropion is less clear.

Implications

This study provides information for the sex-informed treatment of nicotine addiction among cigarette smokers. Relative to placebo, women and men achieved similar outcomes when treated with varenicline; however the advantages of varenicline over transdermal patch and bupropion were greater for women compared to men.

Altered White Matter Integrity in Smokers Is Associated with Smoking Cessation Outcomes

Smoking is a significant cause of preventable mortality worldwide. Understanding the neural mechanisms of nicotine addiction and smoking cessation may provide effective targets for developing treatment strategies. In the present study, we explored whether smokers have white matter alterations and whether these alterations are related to cessation outcomes and smoking behaviors. Sixty-six smokers and thirty-seven healthy non-smokers were enrolled. The participants underwent magnetic resonance imaging scans and smoking-related behavioral assessments. After a 12-week treatment with varenicline, 28 smokers succeeded in quitting smoking and 38 failed. Diffusion parameter maps were compared among the non-smokers, future quitters, and relapsers to identify white matter differences. We found that the future relapsers had significantly lower fractional anisotropy (FA) in the orbitofrontal area than non-smokers, and higher FA in the cerebellum than non-smokers and future quitters. The future quitters had significantly lower FA in the postcentral gyrus compared to non-smokers and future relapsers. Compared to non-smokers, pooled smokers had lower FA in bilateral orbitofrontal gyrus and left superior frontal gyrus. In addition, regression analysis showed that the left orbitofrontal FA was correlated with smoking-relevant behaviors. These results suggest that white matter alterations in smokers may contribute to the formation of aberrant brain circuits underlying smoking behaviors and are associated with future smoking cessation outcomes.

Transcranial magnetic stimulation of the dorsal lateral prefrontal cortex inhibits medial orbitofrontal activity in smokers

BACKGROUND AND OBJECTIVE

Several studies have shown that repetitive transcranial magnetic stimulation (rTMS), applied to the dorsolateral prefrontal cortex (DLPFC), can reduce cue-elicited craving in smokers. Currently, the mechanism of this effect is unknown. We used functional magnetic resonance imaging (fMRI) to explore the effect of a single treatment of rTMS on cortical and sub-cortical neural activity in non-treatment seeking nicotine-dependent participants.

METHODS

We conducted a randomized, counterbalanced, crossover trial in which participants attended two experimental visits separated by at least 1 week. On the first visit, participants received either active, or sham rTMS (10 Hz, 5 s-on, 10 s-off, 100% motor threshold, 3,000 pulses) over the left DLPFC, and on the second visit they received the opposite condition (active or sham). Cue craving fMRI scans were completed before and after each rTMS session.

RESULTS

A total of 11 non-treatment seeking nicotine-dependent cigarette smokers were enrolled in the study [six female, average age 39.7 ± 13.2, average cigarettes per day 17.3 ± 5.9]. Active rTMS decreased activity in the contralateral medial orbitofrontal cortex (mOFC) and ipsilateral nucleus accumbens (NAc) compared to sham rTMS.

CONCLUSIONS

This preliminary data suggests that one session of rTMS applied to the DLPFC decreases brain activity in the NAc and mOFC in smokers.

SCIENTIFIC SIGNIFICANCE

rTMS may exert its anti-craving effect by decreasing activity in the NAc and mOFC in smokers. Despite a small sample size, these findings warrant future rTMS/fMRI studies in addictions. (Am J Addict 2017;26:788-794).

Cdh13 and AdipoQ gene knockout alter instrumental and Pavlovian drug conditioning

Genome-wide association studies in humans have suggested that variants of the cadherin-13 (CDH13) gene are associated with substance use disorder, subjective response to amphetamine, and attention deficit hyperactivity disorder. To examine the role of the Cdh13 and its peptide ligand adiponectin (AdipoQ) in addiction-related behaviors, we assessed Cdh13 knockout (KO) rats and AdipoQ KO mice using intravenous cocaine self-administration and conditioned place preference (CPP) paradigms. During intravenous cocaine self-administration, male Cdh13 heterozygous (+/-) and KO (-/-) rats showed increased cue-induced reinstatement compared with wild-type (WT) rats when presented with a cocaine-paired stimulus, whereas female Cdh13 rats showed no differences across genotype. Cdh13 -/- rats showed higher responding for a saccharin reinforcer and learned the choice reaction time (RT) task more slowly than WTs. However, we found no differences between Cdh13 -/- and +/+ rats in responding for sensory reinforcement, number of premature responses in the RT task, tendency to approach a Pavlovian food cue, CPP and locomotor activation to cocaine (10 or 20 mg/kg). In AdipoQ -/- mice, there was a significant increase in CPP to methamphetamine (1 mg/kg) but not to a range of d-amphetamine doses (0.5, 1, 2 and 4 mg/kg). Taken together, these data suggest that Cdh13 and AdipoQ regulate sensitivity to psychomotor stimulants and palatable rewards without producing major changes in other behaviors. In humans, these two genes may regulate sensitivity to natural and drug rewards, thus influencing susceptibility to the conditioned drug effects and relapse.

Gender differences in the real-world effectiveness of smoking cessation medications: Findings from the 2010-2011 Tobacco Use Supplement to the Current Population Survey

BACKGROUND

Meta-analyses of clinical trial data have identified clinically relevant gender differences in the efficacy of smoking cessation pharmacotherapy. It is unclear whether these findings are generalizable to smokers quitting in real-world contexts.

METHODS

Using Tobacco Use Supplement to the Current Population Survey (TUS-CPS) 2010-2011 cross-sectional data, we generated propensity score matched samples of smokers who quit either unassisted by medication, using only varenicline, or using only transdermal nicotine patch (TNP). We used generalized estimating equations to estimate gender differences in the comparative effectiveness of these cessation options for achieving 30-days of abstinence, adjusting for potential confounders.

RESULTS

When stratified by gender, TNP was significantly more effective than unassisted quit attempts for men (OR=1.37; 95%CI=1.02,1.83; p=0.03), but not for women (OR=0.96; 95%CI=0.71,1.31; p=0.82). Varenicline was significantly more effective than unassisted quit attempts for women (OR=1.63; 95%CI=1.16, 2.31; p=0.005), but not men (OR=1.35; 95%CI=0.94,1.96; p=0.11). Varenicline was also more effective than TNP for women (OR=1.51; 95%CI=0.12,2.05; p=0.007) but not men (OR=0.92; 95%CI=0.65,1.31; p=0.64). A significant gender by medication interaction was found only for the comparison of varenicline to TNP (OR=1.64; 95%CI=1.04,2.61; p=0.04).

CONCLUSIONS

Findings for varenicline vs. TNP were consistent with clinical trial data, showing greater differences in effectiveness for women compared to men. Results lend support to the generalizability of clinical trial findings, highlighting the importance of considering gender when offering treatment for smoking cessation.

Effects of varenicline on alcohol cue reactivity in heavy drinkers

RATIONALE

Clinical trials and human laboratory studies have established that varenicline can reduce rates of alcohol use among heavy drinkers. Less is known about the mechanisms by which varenicline has this effect on drinking behavior. Reactivity to alcohol cues is often cited as the primary cause of relapse among those being treated for alcohol use disorder, and several front-line treatments for alcohol use disorder work, at least in part, by minimizing cue-induced alcohol craving.

OBJECTIVE

The current double-blind, placebo-controlled human laboratory study tested the effects of varenicline on alcohol cue reactivity in a group of heavy-drinking adult smokers and nonsmokers.

METHODS

As part of a larger series of sequential human laboratory experiments testing the effects of varenicline on drinking outcomes, participants were assigned (between-participant) to receive either active varenicline (2 mg/day) or placebo. Following a titration period, participants (n = 77) attended a laboratory session during which they were exposed to alcohol and neutral cues using a standard cue reactivity paradigm.

RESULTS

Alcohol cue exposure increased craving for alcohol in both medication groups. However, participants receiving varenicline showed a smaller increase in alcohol craving compared to participants receiving placebo. The medication effect did not differ between smokers and nonsmokers. Among smokers, alcohol cue exposure also increased tobacco craving. Varenicline did not attenuate this effect.

CONCLUSIONS

Results support the use of varenicline for reducing alcohol use in heavy drinkers and identify a potential mechanism by which varenicline reduces drinking. Varenicline continues to show promise as a pharmacological treatment for alcohol use disorder.

Exercise attenuates negative effects of abstinence during 72 hours of smoking deprivation

Exercise is presumed to be a potentially helpful smoking cessation adjunct reputed to attenuate the negative effects of deprivation. The present study examined the effectiveness of moderate within-session exercise to reduce 4 key symptoms of smoking deprivation during 3 72-hr nicotine abstinence blocks in both male and female smokers. Forty-nine (25 male, 24 female) sedentary smokers abstained from smoking for 3 consecutive days on 3 separate occasions. At each session, smokers' abstinence-induced craving, cue-induced craving, negative mood, and withdrawal symptom severity were assessed prior to and after either exercise (a.m. exercise, p.m. exercise) or a sedentary control activity (magazine reading). Abstinence-induced craving and negative mood differed as a function of condition, F(2, 385) = 21, p < .0001; and, F(2, 385) = 3.38, p = .03. Planned contrasts revealed no difference between a.m. and p.m. exercise, but exercise overall led to greater pre-post reduction in abstinence-induced craving, t(385) = 6.23, p < .0001, effect size Cohen's d = 0.64; and negative mood, t(385) = 2.25, p = .03, d = 0.23. Overall exercise also led to a larger pre-post reduction in cue-induced craving in response to smoking cues, F(2, 387) = 8.94, p = .0002; and withdrawal severity, F(2, 385) = 3.8, p = .02. Unlike the other 3 measures, p.m. exercise reduced withdrawal severity over control, t(385) = 2.64, p = .009, d = 0.27, whereas a.m. exercise did not. The results support the clinical potential of exercise to assist smokers in managing common and robust negative symptoms experienced during the first 3 days of abstinence. (PsycINFO Database Record

Repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex reduces resting-state insula activity and modulates functional connectivity of the orbitofrontal cortex in cigarette smokers

BACKGROUND

Previous studies reported that repetitive transcranial magnetic stimulation (rTMS) can reduce cue-elicited craving and decrease cigarette consumption in smokers. The mechanism of this effect however, remains unclear. We used resting-state functional magnetic resonance imaging (rsfMRI) to test the effect of rTMS in non-treatment seeking smokers.

METHODS

We used a single blinded, sham-controlled, randomized counterbalanced crossover design where participants underwent two visits separated by at least 1 week. Participants received active rTMS over the left dorsolateral prefrontal cortex (DLPFC) during one of their visits, and sham rTMS during their other visit. They had two rsFMRI scans before and after each rTMS session. We used the same rTMS stimulation parameters as in a previous study (10Hz, 5s-on, 10s-off, 100% resting motor threshold, 3000 pulses).

RESULTS

Ten non-treatment-seeking, nicotine-dependent, cigarette smokers (6 women, an average age of 39.72 and an average cigarette per day of 17.30) finished the study. rsFMRI results demonstrate that as compared to a single session of sham rTMS, a single session of active rTMS inhibits brain activity in the right insula and thalamus in fractional amplitude of low frequency fluctuation (fALFF). For intrinsic brain connectivity comparisons, active TMS resulted in significantly decreased connectivity from the site of rTMS to the left orbitomedial prefrontal cortex.

CONCLUSIONS

This data suggests that one session of rTMS can reduce activity in the right insula and right thalamus as measured by fALFF. The data also demonstrates that rTMS can reduce rsFC between the left DLPFC and the medial orbitofrontal cortex.

Increased network centrality as markers of relapse risk in nicotine-dependent individuals treated with varenicline

Identifying smokers at high risk of relapse could improve the effectiveness of cessation therapies. Although altered regional brain function in smokers has been reported, whether the whole-brain functional organization differs smokers with relapse vulnerability from others remains unclear. Thus, the goal of this study is to investigate the baseline functional connectivity differences between relapsers and quitters. Using resting-state fMRI, we acquired images from 57 smokers prior to quitting attempts. After 12-week treatment with varenicline, smokers were divided into relapsers (n=36) and quitters (n=21) (quitter: continuously abstinent for weeks 9-12). The smoking cessation outcomes were cross-validated by self-reports and expired carbon monoxide. We then used eigenvector centrality (EC) mapping to identify the functional connectivity differences between relapsers and quitters. When compared to quitters, increased EC in the right dorsolateral prefrontal cortex (DLPFC), left middle temporal gyrus (MTG) and cerebellum anterior lobe was observed in relapsers. In addition, a logistic regression analysis of EC data (with DLPFC, MTG and cerebellum included) predicted relapse with 80.7% accuracy. These findings suggest that the DLPFC, MTG and cerebellum may be important substrates of smoking relapse vulnerability. The data also suggest that relapse-vulnerable smokers can be identified before quit attempts, which could enable personalized treatment and improve smoking cessation outcomes.