Effect of stress and bupropion on craving, withdrawal symptoms, and mood in smokers

Neurobiology of Stress-Induced Nicotine Relapse

Tobacco smoking is the leading cause of preventable death and disease. Although there are some FAD-approved medicines for controlling smoking, the relapse rate remains very high. Among the factors that could induce nicotine relapse, stress might be the most important one. In the last decades, preclinical studies have generated many new findings that lead to a better understanding of stress-induced relapse of nicotine-seeking. Several molecules such as α3β4 nicotinic acetylcholine receptor, α2-adrenergic receptors, cannabinoid receptor 1, trace amine-associated receptor 1, and neuropeptide systems (corticotropin-releasing factor and its receptors, dynorphine and kappa opioid receptor) have been linked to stress-induced nicotine relapse. In this review, we discuss recent advances in the neurobiology, treatment targets, and potential therapeutics of stress-induced nicotine relapse. We also discuss some factors that may influence stress-induced nicotine relapse and that should be considered in future studies. In the final section, a perspective on some research directions is provided. Further investigation on the neurobiology of stress-induced nicotine relapse will shed light on the development of new medicines for controlling smoking and will help us understand the interactions between the stress and reward systems in the brain.

Effects of neuromodulation on cognitive and emotional responses to psychosocial stressors in healthy humans

Physiological and psychological stressors can exert wide-ranging effects on the human brain and behavior. Research has improved understanding of how the sympatho-adreno-medullary (SAM) and hypothalamic-pituitary-adrenocortical (HPA) axes respond to stressors and the differential responses that occur depending on stressor type. Although the physiological function of SAM and HPA responses is to promote survival and safety, exaggerated psychobiological reactivity can occur in psychiatric disorders. Exaggerated reactivity may occur more for certain types of stressors, specifically, psychosocial stressors. Understanding stressor effects and how the body regulates these responses can provide insight into ways that psychobiological reactivity can be modulated. Non-invasive neuromodulation is one way that responding to stressors may be altered; research into these interventions may provide further insights into the brain circuits that modulate stress reactivity. This review focuses on the effects of acute psychosocial stressors and how neuromodulation might be effective in altering stress reactivity. Although considerable research into stress interventions focuses on treating pathology, it is imperative to first understand these mechanisms in non-clinical populations; therefore, this review will emphasize populations with no known pathology and consider how these results may translate to those with psychiatric pathologies.

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.

Possible New Symptoms of Tobacco Withdrawal III: Reduced Positive Affect-A Review and Meta-analysis

INTRODUCTION

Most descriptions of tobacco withdrawal have not changed in >30 years despite new research. This meta-analysis tested whether abstinence leads to decreased positive affect (PA) because abstinence-induced symptom changes are a core feature of the tobacco withdrawal syndrome. In addition, we examined whether reduced PA was due to withdrawal (ie, temporary decrease in a "U-shaped" curve) or offset (ie, return to baseline) effect.

METHODS

Our main inclusion criterion was a prospective within-participant test of change in PA during abstinence conditions among people who smoke cigarettes daily who were not using a cessation medication. Our search of PubMed, PsycINFO, and personal libraries yielded a total of 32 tests with 2054 participants.

RESULTS

There was a medium effect size indicating an overall decrease in PA following abstinence from cigarettes (Cohen's d = -0.40, 95% CI = -0.30 to -0.49). There was large heterogeneity (I2 = 70.7%). Most (79%) of the 24 trials that conducted significance tests reported that reduction in PA was significant. Seven tests were adequately designed to detect a withdrawal versus offset effect. Over half (57%) displayed a U-shaped curve for abstinence-induced change in PA indicative of a withdrawal symptom rather than offset effect.

CONCLUSIONS

Abstinence from cigarettes is associated with a decrease in PA. Whether low PA should be added to withdrawal measures and diagnostic criteria requires replication of the time-course of change in PA and tests of whether abstinence-induced changes in PA and negative affect occur independently.

IMPLICATIONS

Though there was substantial heterogeneity among trials, our findings suggest that (1) abstinence from cigarettes decreases positive affect and (2) this decrease may represent a withdrawal effect (vs. an offset effect). However, it is unclear whether abstinence-induced losses in positive affect are independent from increased negative affect.

Efficacy of a short-term residential smoking cessation therapy versus standard outpatient group therapy ('START-Study'): study protocol of a randomized controlled trial

BACKGROUND

In Germany, evidence-based outpatient smoking cessation therapies are widely available. Long-term abstinence rates, however, are limited. Studies suggest that short-term residential therapy enables a higher level of environmental control, more intense contact and greater support among patients and from therapists, which could result in higher abstinence rates. The aim of the current START-study is to investigate the long-term efficacy of a short-term residential therapy exclusively for smoking cessation, conducted by a mobile team of expert therapists.

METHODS

A randomized controlled trial (RCT) is conducted to examine the efficacy of residential behavior therapeutic smoking cessation therapy compared to standard outpatient behavior therapeutic smoking cessation group therapy. Adult smokers consuming 10 or more cigarettes per day, who are willing to stop smoking, are randomized in a ratio of 1:1 between therapy groups. The primary endpoint is sustained abstinence for 6-month and 12-month periods. Secondary endpoints include smoking status after therapy, 7-day point abstinence after the 6-month and 12-month follow-ups, level of physical dependence, cost-effectiveness, use of nicotine replacement products, health-related quality of life, self-efficacy expectation for tobacco abstinence, motivational and volitional determinants of behavior change, self-reported depressive symptom severity, adverse events and possible side effects. Assessments will take place at baseline, post-therapy, and at 6-month and 12-month intervals after smoking cessation.

DISCUSSION

There is a high demand for long-term effective smoking cessation therapies. This study represents the first prospective RCT to examine the long-term efficacy of a residential smoking cessation therapy program compared to standard outpatient group therapy as an active control condition. The residential therapeutic concept may serve as a new model to substantially enhance future cessation therapies and improve the understanding of therapeutic impact factors on tobacco abstinence. Utilizing a mobile team, the model could be applied efficiently to medical centers that do not have permanent and trained personnel for smoking cessation at their disposal.

TRIAL REGISTRATION

German Register for Clinical Trials (Deutsches Register für Klinische Studien), DRKS00013466. Retrospectively registered on 1 April 2019. https://www.drks.de/drks_web/navigate.do?navigationId=start.

Randomized Clinical Trials Investigating Innovative Interventions for Smoking Cessation in the Last Decade

Every year, billions of dollars are spent treating smoking and related conditions, yet smoking-related morbidity and mortality continue to rise. There are currently only three FDA-approved medications for smoking cessation: nicotine replacement therapy, bupropion, and varenicline. Although these medications increase abstinence rates, most individuals relapse following treatment. This chapter reviews clinical trials published within the past 10 years investigating novel smoking cessation pharmacotherapies. Among these pharmacotherapies, some showed promising results, such as cytisine and endocannabinoid modulators, whereas others failed to produce significant effects. More research is needed to develop drugs that produce higher rates of long-term abstinence and to determine which subgroups of patients benefit from a given treatment.

Post-sexual assault cigarette smoking: Findings from a randomized clinical trial of a video-based intervention

Sexual assault (SA) is associated with elevated risk for cigarette smoking. The current study tested whether a brief video intervention delivered in the emergency department was effective at reducing smoking following SA. Participants were 233 girls and women (age 15+) who received a SA medical forensic examination (SAMFE) and were randomized to one of three conditions: 1) Prevention of Post-Rape Stress (PPRS), a brief video designed to reduce post-SA psychopathology; 2) Pleasant Imagery and Relaxation Information (PIRI), an active control video involving relaxation training; and 3) treatment as usual (TAU). Among those who participated at baseline, 154 participants completed at least one follow-up at 1.5, 3, and 6 months after the SAMFE. Participants reported the number of days of smoking and the average number of cigarettes smoked per day in the two weeks prior to the sexual assault as well as in the two weeks prior to each follow-up. Two-thirds (68.8%) of participants smoked prior to the SA or during any follow-up. One-fifth of participants who did not smoke prior to the SA smoked at one or more follow-ups. Smoking declined on average over follow-up although TAU was associated with increased initial smoking compared to PPRS; PPRS and PIRI did not differ. SA contributes to increases in smoking and the PPRS, a brief and cost-effective video-based intervention delivered during the SAMFE, can protect against increases in post-SA smoking. Trial registration: NCT01430624.

Pain characteristics and nicotine deprivation as predictors of performance during a laboratory paradigm of smoking cessation

Although smokers with co-occurring pain report expectations for experiencing greater nicotine withdrawal and difficulty quitting, limited work has examined the role of pain in cessation-related outcomes. The goal of this study was to examine clinically relevant pain characteristics (pain persistence, pain intensity, pain-related disability) as predictors of withdrawal and smoking lapse/relapse outcomes using a laboratory paradigm of cessation. Participants (N = 120 daily cigarette smokers; 48% male; M_age = 36.17, SD = 12.16; M_{Cigarettes Per Day} = 20.51, SD = 6.99) were randomized to either nondeprived or 12-hr nicotine deprivation conditions prior to an experimental study visit. Upon arrival to the laboratory, participants completed measures of pain characteristics and nicotine withdrawal symptoms. Primary outcomes included nicotine withdrawal scores and analogues of smoking lapse (latency to initiating smoking) and relapse (number of cigarettes smoked). We hypothesized that smokers with greater pain persistence, pain intensity, and pain-related disability would endorse more severe nicotine withdrawal and greater lapse/relapse behavior, and that these positive associations would be stronger among those who were nicotine deprived. Results indicated that, above and beyond the effect of nicotine deprivation, persistent pain predicted more severe nicotine withdrawal, and that greater pain-related disability predicted quicker latency to lapse during the laboratory paradigm. Contrary to expectation, nicotine deprivation did not moderate effects of pain characteristics on withdrawal or lapse/relapse outcomes. Clinical implications include that different pain processes may influence different cessation outcomes, and that smokers in pain may benefit from the provision of pharmacological aids to better control withdrawal symptoms. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Effects of smoking and paroxetine on stress-induced craving and withdrawal symptoms

Background

When smokers relapse, many cite stressful circumstances as the cause. Most smoking cessation medications do not prevent stress induced increases in craving and withdrawal symptom severity; however the effect of smoking prior to stress exposure on symptom severity is unclear.

Methods

We examined how smoking a cigarette immediately prior to a stressful task affects craving and withdrawal symptom severity by analyzing data from a double-blind, crossover study assessing paroxetine's effects on the physiological response to the combination of stress and smoking. Measures were obtained prior to and following smoking / stress exposure and following a subsequent 30 minute period at two laboratory sessions (i.e., after one month each of paroxetine and placebo).

Results

Among study completers (n=63), severity of craving decreased from the beginning of the session to immediately following the smoking / stress exposure (p<0.01) and severity of smoking urges decreased from the beginning to the end of the laboratory session (p<0.001). Withdrawal symptoms were less severe while taking paroxetine vs. placebo (p<0.05) but no treatment x time effects were observed.

Conclusions

Additional research is needed to identify interventions that could similarly decrease stress induced craving in order to determine if smoking cessation rates can be increased.

Timing of nicotine lozenge administration to minimize trigger induced craving and withdrawal symptoms

INTRODUCTION

Smokers are often advised to use nicotine lozenge when craving or withdrawal symptoms occur. This may be too late to prevent lapses. This study assessed if nicotine lozenge use prior to a common smoking trigger can minimize trigger induced increases in craving and withdrawal symptoms.

METHODS

Eighty-four smokers completed two laboratory sessions in random order. At one session, nicotine lozenge was given immediately after a stressor (to approximate current recommended use - i.e., after craving and withdrawal symptoms occur); at the other session subjects were randomized to receive nicotine lozenge at time points ranging from immediately to 30min prior to the stressor. Withdrawal symptoms and urge to smoke were measured using the Minnesota Nicotine Withdrawal Scale and the Questionnaire of Smoking Urges (QSU).

RESULTS

Relative to receiving lozenge after the stressor, a smaller increase in pre-stressor to post-stressor withdrawal symptom scores occurred when lozenge was used immediately (p=0.03) and 10min prior (p=0.044) to the stressor. Results were similar for factors 1 and 2 of the QSU when lozenge was used immediately prior to the stressor (p<0.03) and for factor 1 of the QSU when lozenge was used 10min prior to the stressor (p=0.028). Absolute levels of post-stressor withdrawal symptom and urge to smoke severity were lower when lozenge was given prior to versus after a stressor.

CONCLUSIONS

Administering the nicotine lozenge prior to a smoking trigger can decrease trigger induced craving and withdrawal symptoms. Future studies are needed to determine if such use would increase cessation rates. Clinicaltrials.gov # NCT01522963.

A Randomized Trial Evaluating Whether Topiramate Aids Smoking Cessation and Prevents Alcohol Relapse in Recovering Alcohol-Dependent Men

BACKGROUND

Alcohol and nicotine dependence frequently co-occur, and quitting smoking might enhance long-term alcohol abstinence. Topiramate appears to help non-alcohol-dependent individuals quit smoking, and our pilot work suggested efficacy only in men. It also prevents relapse to alcohol in recently detoxified alcoholics. We evaluated topiramate in abstinent alcohol-dependent men to assess whether this medication (i) promotes smoking cessation and (ii) prevents alcohol and other drug relapse in the context of smoking cessation treatment.

METHODS

One hundred and twenty-nine alcohol-abstinent (mean ~6 months) alcohol-dependent male smokers (80% with other substance use disorders) participated in this 12-week randomized, double blind, parallel group comparison of topiramate (up to 200 mg/d) and placebo with a 24-week nontreatment follow-up period. The study was carried out sequentially at 2 academic centers in the Midwest and Southern California between March 23, 2009 and November 20, 2014. All participants received manual-guided smoking cessation counseling combined with medication-focused compliance enhancement therapy. Randomization was block designed by the research pharmacist in a 1:1 ratio. Participants, investigators, and research personnel were masked to treatment assignment. The primary smoking end point was biochemically confirmed 4-week continuous abstinence from smoking during weeks 9 to 12, while the secondary end point was relapse to any drinking or drug use during the entire 36-week evaluation period. Logistic regression was used to determine the effects of topiramate on quitting smoking and alcohol relapse, controlling for relevant covariates. The trial is registered at ClinicalTrials.gov (number NCT00802412) and is now closed.

RESULTS

Only a small proportion (7.9%) of topiramate-treated participants were able to quit smoking, and this cessation rate was similar to placebo (10.6%; odds ratio = 1.60; 95% confidence interval 0.4, 6.5; p = 0.51). Roughly 30% of the sample had a documented relapse to drinking or drug use during the study, and these rates were similar in the topiramate (20/63; 31.8%) and placebo groups (18/66; 27.3%; p = 0.58). Results of a longitudinal logistic regression model examining time to any alcohol relapse revealed no medication effect.

CONCLUSIONS

Topiramate at a daily dosage of up to 200 mg per day, combined with smoking cessation and medication adherence counseling, had no effects on smoking cessation or the prevention of alcohol or drug relapse in male smokers who were in early or sustained full remission from alcohol and motivated to make a quit attempt. Alternative approaches for treating this high-risk, dually dependent population are needed.

Putative Epigenetic Involvement of the Endocannabinoid System in Anxiety- and Depression-Related Behaviors Caused by Nicotine as a Stressor

Like various stressors, the addictive use of nicotine (NC) is associated with emotional symptoms such as anxiety and depression, although the underlying mechanisms have not yet been fully elucidated due to the complicated involvement of target neurotransmitter systems. In the elicitation of these emotional symptoms, the fundamental involvement of epigenetic mechanisms such as histone acetylation has recently been suggested. Furthermore, among the interacting neurotransmitter systems implicated in the effects of NC and stressors, the endocannabinoid (ECB) system is considered to contribute indispensably to anxiety and depression. In the present study, the epigenetic involvement of histone acetylation induced by histone deacetylase (HDAC) inhibitors was investigated in anxiety- and depression-related behavioral alterations caused by NC and/or immobilization stress (IM). Moreover, based on the contributing roles of the ECB system, the interacting influence of ECB ligands on the effects of HDAC inhibitors was evaluated in order to examine epigenetic therapeutic interventions. Anxiety-like (elevated plus-maze test) and depression-like (forced swimming test) behaviors, which were observed in mice treated with repeated (4 days) NC (subcutaneous 0.8 mg/kg) and/or IM (10 min), were blocked by the HDAC inhibitors sodium butyrate (SB) and valproic acid (VA). The cannabinoid type 1 (CB1) agonist ACPA (arachidonylcyclopropylamide; AC) also antagonized these behaviors. Conversely, the CB1 antagonist SR 141716A (SR), which counteracted the effects of AC, attenuated the anxiolytic-like effects of the HDAC inhibitors commonly in the NC and/or IM groups. SR also attenuated the antidepressant-like effects of the HDAC inhibitors, most notably in the IM group. From these results, the combined involvement of histone acetylation and ECB system was shown in anxiety- and depression-related behaviors. In the NC treatment groups, the limited influence of SR against the HDAC inhibitor-induced antidepressant-like effects may reflect the characteristic involvement of histone acetylation within the NC-related neurotransmitter systems other than the ECB system.

The safety of treatments for tobacco use disorder

INTRODUCTION

Tobacco continues to be a leading cause of preventable morbidity and mortality in the world. First-line pharmacotherapies for the treatment of tobacco use disorder include nicotine replacement therapy, bupropion sustained-release (SR), and varenicline. We provide an overview of current evidence on the safety of first-line pharmacotherapies for the treatment of tobacco use disorder.

AREAS COVERED

Randomized clinical trials published in English up to July 2015 were identified and reviewed through searches of PUBMED using the terms nicotine replacement therapy, bupropion SR, varenicline, smoking, and tobacco cessation.

EXPERT OPINION

Nicotine replacement has few contraindications and side effects and can be recommended to almost all tobacco users. Bupropion SR should be used with caution in patients with bipolar disorder or liver or kidney disease, and alternative treatments should be considered for patients with a history of seizures or who are at risk for seizures. The only contraindication for varenicline is an allergy to the medication, and nausea is the most common side effect. Varenicline can be used safely in patients with cardiovascular disease. Varenicline can be used in patients with stable psychiatric disease and safety can be ensured through close clinical monitoring.

Time-varying effects of a text-based smoking cessation intervention for urban adolescents

INTRODUCTION

Craving to smoke is understood as an important mechanism for continued smoking behavior. Identifying how smoking interventions operate on craving with particular populations is critical for advancing intervention science. This study's objective was to investigate the time-varying effect of a text-delivered smoking cessation intervention.

METHODS

Toward this end, we used ecological momentary assessment (EMA) data collected from a five-day, automated text-messaging smoking cessation randomized clinical trial with 200 urban adolescents. We employed a time-varying effect model (TVEM) to estimate the effects of stress (time-varying covariate) and baseline nicotine dependence level (time-invariant covariate) on craving over six months by treatment condition. The TVEM approach models behavioral change and associations of coefficients expressed dynamically and graphically represented as smooth functions of time.

RESULTS

Controlling for gender, age, and current smoking, differences in trajectories of craving between intervention and control conditions were apparent over the course of the study. During months 2 to 3, the association between stress and craving was significantly stronger among the control group, suggesting treatment dampens this association during this time period. The intervention also reduced the salience of baseline dependence among treatment adolescents, with craving being reduced steadily over time, while the control group increased craving over time.

CONCLUSIONS

These results provide insight into the time-varying nature of treatment effects for adolescents receiving a text-based smoking cessation intervention. The ability to specify when in the course of an intervention the effect is strongest is important in developing targeted and adaptive interventions that can adjust strategically with time.

Pharmacological means of reducing human drug dependence: a selective and narrative review of the clinical literature

Substance abuse or addictive disorder is a global problem. A greater understanding of the associated changes in brain pathophysiology supports the notion that pharmacological treatments are part of the necessary treatment options. Craving is a core symptom of addictive disorder. It refers to a strong desire to use drugs again either to re-experience positive effects or to diminish negative experiences. Currently there are a number of medicines that are effective in the treatment of addictive disorders. These medications can either be for substitution (same pharmacological effect as the abused substance) or anticraving (decrease the craving of the abused substance). In this MEDLNE based review, specific compounds (naltrexone, acamprosate, topiramate, disulfiram, baclofen, N-acetylcysteine and bupropion) were selected that are known to diminish desire to use (anticraving effect) and that have been trialled for a number of different substance addictive disorders. Their therapeutic potential in clinical practice is discussed in light of their efficacy.

Emerging drugs for the treatment of tobacco dependence: 2014 update

INTRODUCTION

Tobacco dependence remains a global epidemic and the largest preventable cause of morbidity and mortality around the world. Smoking cessation has benefits at all ages but remains challenging for several reasons, among which are the complexities of nicotine addiction and limitations of available pharmacotherapies.

AREAS COVERED

This review summarizes current and emerging pharmacotherapies for the treatment of tobacco dependence, including first- and second-line recommended agents. Medications with alternative primary indications that have been investigated as potential treatments for tobacco dependence are also discussed. Articles reviewed were obtained through searches of PubMed, Ovid MEDLINE, ClinicalTrials.gov and the Pharmaprojects database.

EXPERT OPINION

Current evidence suggests that the two most effective pharmacotherapies to treat tobacco dependence are varenicline and combination nicotine replacement therapy. Alternative agents investigated demonstrate mixed rates of success in achieving long-term abstinence from smoking. No single pharmacotherapy will serve as a universally successful treatment given the complex underpinnings of tobacco dependence and individuality of smokers. The ultimate goal of tobacco research with respect to pharmacotherapeutic development continues to be providing clinicians with an armamentarium of drugs to choose from allowing for tailoring of treatment for smokers.

Stress modulates illness-course of substance use disorders: a translational review

Childhood trauma and post-childhood chronic/repeated stress could increase the risk of a substance use disorder by affecting five stages of addiction illness-course: (a) initial experimentation with substances; (b) shifting from experimental to regular use; (c) escalation from regular use to abuse or dependence; (d) motivation to quit; and (e) risk of (re-)lapse. We reviewed the human literature on relationships between stress and addiction illness-course. We explored per illness-course stage: (i) whether childhood trauma and post-childhood chronic/repeated stress have comparable effects and (ii) whether effects cut across classes of substances of abuse. We further discuss potential underlying mechanisms by which stressors may affect illness-course stages for which we relied on evidence from studies in animals and humans. Stress and substances of abuse both activate stress and dopaminergic motivation systems, and childhood trauma and post-childhood stressful events are more chronic and occur more frequently in people who use substances. Stressors increase risk to initiate early use potentially by affecting trait-like factors of risk-taking, decision making, and behavioral control. Stressors also accelerate transition to regular use potentially due to prior effects of stress on sensitization of dopaminergic motivation systems, cross-sensitizing with substances of abuse, especially in people with high trait impulsivity who are more prone to sensitization. Finally, stressors increase risk for abuse and dependence, attenuate motivation to quit, and increase relapse risk potentially by intensified sensitization of motivational systems, by a shift from positive to negative reinforcement due to sensitization of the amygdala by corticotropin releasing factor, and by increased sensitization of noradrenergic systems. Stress generally affects addiction illness-course across stressor types and across classes of substances of abuse.

Working memory- and anxiety-related behavioral effects of repeated nicotine as a stressor: the role of cannabinoid receptors

Background

Like emotional symptoms such as anxiety, modulations in working memory are among the frequently-reported but controversial psychiatric symptoms associated with nicotine (NC) administration. In the present study, repeated NC-induced modulations in working memory, along with concurrently-observed anxiety-related behavioral alterations, were investigated in mice, and compared with the effects of a typical cognition-impairing stressor, immobilization stress (IM). Furthermore, considering the structural and functional contributions of brain cannabinoid (CB) receptors in NC-induced psychiatric symptoms including emotional symptoms, the interactive effects of brain CB receptor ligands (CB ligands) and NC and/or IM on the working memory- and anxiety-related behaviors were examined.

Results

Statistically significant working memory impairment-like behavioral alterations in the Y-maze test and anxiety-like behavioral alterations in the elevated plus-maze (EPM) test were observed in the groups of mice treated with 0.8 mg/kg NC (subcutaneous (s.c.) 0.8 mg/kg treatment, 4 days) and/or IM (10 min treatment, 4 days). In the group of mice treated with NC plus IM (NC-IM group), an enhancement of the behavioral alterations was observed. Among the CB type 1 (CB1) antagonist AM 251 (AM), the non-selective CB agonist CP 55,940 (CP), and the CB1 partial agonist/antagonist virodhamine (VD), significant recovering effects were provided by AM (0.2-2.5 mg/kg) and VD (5 mg/kg) against the working memory impairment-like behaviors, whereas significant anxiolytic-like effects (recoveries from both attenuated percentage of entries into open arms and attenuated percentage of time spent on open arms) were provided by VD (1–10 mg/kg) and CP (2 mg/kg) against the anxiety-like behaviors.

Conclusions

Although working memory impairment- and anxiety-like behavioral alterations were commonly induced in the NC, IM, and NC-IM groups and the therapeutic involvement of CB receptors was shown, there were discrepancies in the types of effective CB ligands between the working memory- and anxiety-related behaviors. The differential involvements of CB receptor subtypes and indirectly activated neurotransmitter systems may contribute to these discrepancies.

Pain, nicotine, and smoking: research findings and mechanistic considerations

Tobacco addiction and chronic pain represent 2 highly prevalent and comorbid conditions that engender substantial burdens upon individuals and systems. Interrelations between pain and smoking have been of clinical and empirical interest for decades, and research in this area has increased dramatically over the past 5 years. We conceptualize the interaction of pain and smoking as a prototypical example of the biopsychosocial model. Accordingly, we extrapolated from behavioral, cognitive, affective, biomedical, and social perspectives to propose causal mechanisms that may contribute to the observed comorbidity between these 2 conditions. The extant literature was 1st dichotomized into investigations of either effects of smoking on pain or effects of pain on smoking. We then integrated these findings to present a reciprocal model of pain and smoking that is hypothesized to interact in the manner of a positive feedback loop, resulting in greater pain and increased smoking. Finally, we proposed directions for future research and discussed clinical implications for smokers with comorbid pain disorders. We observed modest evidence that smoking may be a risk factor in the multifactorial etiology of some chronically painful conditions and that pain may come to serve as a potent motivator of smoking. We also found that whereas animal studies yielded consistent support for direct pain-inhibitory effects of nicotine and tobacco, results from human studies were much less consistent. Future research in the emerging area of pain and smoking has the potential to inform theoretical and clinical applications with respect to tobacco smoking, chronic pain, and their comorbid presentation. (PsycINFO Database Record (c) 2011 APA, all rights reserved).