Behavioral and cognitive effects of smoking: relationship to nicotine addiction

Awareness and Perception Toward Nicotine Replacement Therapy Among Medical Students at Umm Al-Qura University

Background Tobacco smoking is a leading cause of premature mortality worldwide, with most deaths attributed to smoking-related diseases. Quitting smoking can have significant health benefits and increase one's lifespan. Nicotine, the addictive component of tobacco, can lead to cravings and withdrawal symptoms. Nicotine replacement therapy (NRT) can be an effective aid in easing these symptoms. This study aimed to estimate the awareness, acceptance, knowledge, and perception of NRT among medical students at Umm Al-Qura University in Makkah City. Methodology A cross-sectional survey method using Google Forms was utilized to distribute a questionnaire among medical students. The data were analyzed data using RStudio with statistical significance set at p-values <0.05. Results Of the 310 students included in this study, the majority were males (56.5%) and were aged between 21 and 24 years. Overall, 31.9% of the participants were in their fourth year of study. Regression analysis showed that being in the fifth or sixth academic year significantly predicted awareness of NRT. Conclusions Senior-year medical students had more knowledge and awareness about NRT than their junior colleagues. Future recommendations are vital for medical students to increase their knowledge, awareness, and practice regarding NRT.

Using systems science to advance health equity in tobacco control: a causal loop diagram of smoking

OBJECTIVES

Develop and use a causal loop diagram (CLD) of smoking among racial/ethnic minority and lower-income groups to anticipate the intended and unintended effects of tobacco control policies.

METHODS

We developed a CLD to elucidate connections between individual, environmental and structural causes of racial/ethnic and socioeconomic disparities in smoking. The CLD was informed by a review of conceptual and empirical models of smoking, fundamental cause and social stress theories and 19 qualitative interviews with tobacco control stakeholders. The CLD was then used to examine the potential impacts of three tobacco control policies.

RESULTS

The CLD includes 24 constructs encompassing individual (eg, risk perceptions), environmental (eg, marketing) and structural (eg, systemic racism) factors associated with smoking. Evaluations of tobacco control policies using the CLD identified potential unintended consequences that may maintain smoking disparities. For example, the intent of a smoke-free policy for public housing is to reduce smoking among residents. Our CLD suggests that the policy may reduce smoking among residents by reducing smoking among family/friends, which subsequently reduces pro-smoking norms and perceptions of tobacco use as low risk. On the other hand, some residents who smoke may violate the policy. Policy violations may result in financial strain and/or housing instability, which increases stress and reduces feelings of control, thus having the unintended consequence of increasing smoking.

CONCLUSIONS

The CLD may be used to support stakeholder engagement in action planning and to identify non-traditional partners and approaches for tobacco control.

Association of smoking with the survival of patients with brain metastasis of lung cancer

Background

Smoking is associated with increased mortality in patients with cancer. However, there are limited data on the impact of smoking on the survival of patients with brain metastases. Therefore, this study aimed to evaluate whether smoking was associated with survival and whether smoking cessation was beneficial to these patients.

Methods

This study used lung cancer with a brain metastasis cohort of the West China Hospital of Sichuan University from 2013 to 2021. Patients were stratified according to smoking history; the distribution, clinical characteristics, and survival data of each group were estimated. Kaplan-Meier analysis and risk analysis were performed for the survival endpoint.

Results

Of the 2,647 patients included in the analysis, the median age was 57.8 years, and 55.4% were men. Among them, 67.1% had no smoking history, 18.9% still smoked, and 14% reported quitting smoking. Compared with never smokers, current smokers [HR, 1.51 (95% CI, 1.35-1.69), p &lt; 0.01] and former smokers [HR, 1.32 (95% CI, 1.16-1.49), p&lt;0.01] had an increased risk of death. However, quitting smoking was not associated with improved survival [HR, 0.90 (95% CI, 0.77-1.04), p = 0.16]. The overall survival increased with the increase of smoking cessation years.

Conclusions

In lung cancer patients with brain metastases, smoking was associated with an increased risk of death, but quitting smoking was not associated with improved survival.

Cumulative vulnerabilities and smoking abstinence: A test from a randomized clinical trial

Smoking cessation is often associated with socioeconomic and intrapersonal vulnerabilities such as psychopathology. Yet, most research that focuses on predicting smoking cessation outcomes tends focus on a small number of possible vulnerabilities. In a secondary data analysis, we developed and empirically evaluated a comprehensive, cumulative vulnerability risk composite reflecting psychologically based transdiagnostic processes, social determinants of health, and psychopathology. Participants were adult smokers who responded to study advertisements (e.g., flyers, newspaper ads, radio announcements) for an in-person delivered 4-session smoking cessation trial (N = 267; 47% female; Mage = 39.4, SD = 13.8). Results indicated that the decline in point prevalence abstinence (PPA) from quit week to 6-month post-quit was statistically significant (p < .001). There were statistically significant effects of cumulative risk score on the intercept (p < .001) and slope (p = .01). These findings were evident in unadjusted and adjusted (controlling for sex, treatment condition, and nicotine dependence) models. The present results indicate smokers with greater cumulative vulnerability demonstrated poorer smoking cessation outcomes. There may be clinical advantages to better understanding cumulative vulnerability among treatment-seeking smokers and other smoking populations to enhance the impact of public health efforts to reduce smoking.

Development of a multi-component tobacco cessation training package utilizing multiple approaches of intervention development for health care providers and patients attending non-communicable disease clinics of Punjab, India

Background

Providing patients with personalized tobacco cessation counseling that is culturally sensitive, and disease-specific from healthcare providers (HCPs) as part of their routine consultations is an approach that could be incorporated, using existing healthcare systems such as the Non-Communicable Disease (NCD) clinics. This paper describes the development of a multi-component culturally tailored, patient-centric, disease-specific tobacco cessation package utilizing multiple approaches of intervention development for healthcare providers and patients attending these clinics in Punjab, India, along with a proposed framework for implementation.

Methods

The proposed intervention package was developed in 6 stages. These included a review of literature for identifying successful cessation interventions for ethnic minority groups, co-production of the package with all stakeholders involved via a series of consultative meetings and workshops, understanding contextual factors of the state and 'factor-in' these in the package, pre-test of the package among HCPs and tobacco users using in-depth interviews, micro detailing and expansion of the package by drawing on existing theories of the Cascade Model and Trans-Theoretical Model and developing an evolving analysis plan through real-world implementation at two pilot districts by undertaking a randomized controlled trial, assessing implementer's experiences using a mixed-method with a primary focus on qualitative and economic evaluation of intervention package.

Results

A multi-component package consisting of a booklet (for HCPs), disease-specific pamphlets and short text messages (for patients; bilingual), and an implementation framework was developed using the 6-step process. A major finding from the in-depth interviews was the need for a specific capacity-building training program on tobacco cessation. Therefore, using this as an opportunity, we trained the in-service human resource and associated program managers at the state and district-level training workshops. Based on the feedback, training objectives were set and supported with copies of intervention package components. In addition, the role and function of each stakeholder were defined in the proposed framework.

Conclusion

Consideration of tobacco users' socio-cultural and patient-centric approach makes a robust strategy while developing and implementing an intervention providing an enlarged scope to improve care services for diversified socio-cultural communities.

Effect of progesterone administration in male and female smokers on nicotine withdrawal and neural response to smoking cues: role of progesterone conversion to allopregnanolone

BACKGROUND

Progesterone administration has therapeutic effects in tobacco use disorder (TUD), with females benefiting more than males. Conversion of progesterone to the neurosteroid allopregnanolone is hypothesized to partly underlie the therapeutic effects of progesterone; however, this has not been investigated clinically.

METHODS

Smokers (n = 18 males, n = 21 females) participated in a randomized, double-blind, placebo-controlled crossover study of 200 mg progesterone daily across 4 days of abstinence. The ratio of allopregnanolone:progesterone was analyzed in relationship to nicotine withdrawal, smoking urges, mood states, subjective nicotine effects, and neural response to smoking cues.

RESULTS

Allopregnanolone:progesterone ratio interacted with sex to predict withdrawal symptoms (p = 0.047), such that females with higher allopregnanolone:progesterone ratios reported lower withdrawal severity (b = - 0.98 [- 1.95, - 0.01]; p = 0.048). In addition, allopregnanolone:progesterone ratio interacted with sex to predict confusion (p = 0.014) and fatigue (p = 0.034), such that females with higher allopregnanolone:progesterone ratios reported less confusion (b = - 0.45 [- 0.78, - 0.12]; p = 0.008) and marginally lower fatigue (b = - 0.50 [- 1.03, 0.02]; p = 0.062. Irrespective of sex, higher ratios of allopregnanolone:progesterone were associated with stronger "good effects" of nicotine (b = 8.39 [2.58, 14.20]); p = 0.005) and weaker "bad effects" of nicotine (b = - 7.13 [- 13.53, - 0.73]; p = 0.029).

CONCLUSIONS

Conversion of progesterone to allopregnanolone correlated with smoking-related outcomes in both sex-dependent and sex-independent ways. Sex-dependent effects suggest that conversion of progesterone to allopregnanolone may contribute to greater therapeutic benefits in females but not males with TUD. Trial registration Clinicaltrials.gov registration, retrospectively registered: NCT01954966; https://clinicaltrials.gov/ct2/show/NCT01954966 \.

Molecular docking and dynamics studies of cigarette smoke carcinogens interacting with acetylcholinesterase and butyrylcholinesterase enzymes of the central nervous system

The free radicals produced by cigarette smoking are responsible for tissue damage, heart and lung diseases, and carcinogenesis. The effect of tobacco on the central nervous system (CNS) has received increased attention nowadays in research. Therefore, to explore the molecular interaction of cigarette smoke carcinogens (CSC) 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanol (NNAL), 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanone (NNK), and N'-nitrosonornicotine (NNN) with well-known targets of CNS-related disorders, acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) enzymes, a cascade of the computational study was conducted including molecular docking and molecular dynamics simulations (MDS). The investigated results of NNAL+AChEcomplex, NNK+AChEcomplex, and NNK+BuChEcomplex based on intermolecular energies (∆G) were found to -8.57 kcal/mol, -8.21 kcal/mol, and -8.08 kcal/mol, respectively. MDS deviation and fluctuation plots of the NNAL and NNK interaction with AChE and BuChE have shown significant results. Further, Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) results shown the best total binding energy (Binding∆G) -87.381 (+/-13.119) kJ/mol during NNK interaction with AChE. Our study suggests that CSC is well capable of altering the normal biomolecular mechanism of CNS; thus, obtained data could be useful to design extensive wet laboratory experimentation to know the effects of CSC on human CNS.

Evaluating the impact of culturally specific patient-centric behavioral intervention package versus usual care for tobacco cessation among patients attending noncommunicable disease clinics in North India: A single-blind trial pilot study protocol

Background

In a low and middle-income country (LMIC) like India, non—communicable diseases (NCDs) contribute a major proportion (61.8%) of all causes of death. Out of this, 48% of cardiovascular diseases , 23% of Chronic Respiratory Diseases , and 10% of Cancer deaths are attributable to tobacco use. Tobacco use is a major risk factor for NCDs and thus, the tobacco cessation approach is a high priority intervention to combat complications and death among NCD patients. While several interventions are available for tobacco cessation, in resource constraint countries like India, the effectiveness of low-cost, culturally specific patient-centric tobacco cessation behavioral intervention holds a potential that needs to be evaluated. A newly developed evidence-based tobacco cessation intervention package will be compared with the existing/usual care provided under the National Programme for Prevention and Control of Cancers, Diabetes, Cardiovascular Diseases, and Stroke (NPCDCS) at NCD clinics.

Methods and design

2 arm, parallel-group randomized controlled trial.

Participants

Patients aged ≥30 years suffering from NCD, currently using tobacco, and attending NCD clinics in 2 districts of Punjab, India.

Sample size

A total of 200 participants meeting the selection criteria will be recruited. They will be allocated either to the intervention arm or control (usual care) arm (100 each) using block randomization.

Intervention

For the participants, there will be 4 face-to-face disease-specific cessation counseling sessions, disease-specific pamphlets, short text messages in vernacular language, that is, Punjabi. Follow-ups will be done at the third, sixth, ninth, and 12th months.

Primary outcome

Seven-day abstinence, biochemically verified by plasma cotinine levels.

Secondary outcome

Quit attempts, number of sticks/number of times of smokeless tobacco usage in a day, and stage of behavior change in tobacco users.

Discussion

This multicomponent culturally specific-patient-centric behavioral intervention package for tobacco cessation at NCD clinic settings focusing on the individual, family, and social environment could increase the outreach of cessation services using existing resources, thereby strengthening health systems and enhancing the quality of life of NCD patients.

Trial registration

The protocol for the study has been registered with the Clinical Trials Registry in India under the registration number CTRI/2018/01/011643.

Nicotine promotes brain metastasis by polarizing microglia and suppressing innate immune function

Up to 40% of lung cancer patients develop brain metastasis, and the median survival of these patients remains less than 6 months. Smoking is associated with lung cancer. However, how smoking impacts the development of brain metastasis remains elusive. We examined 281 lung cancer patients with distant metastasis and found that smokers exhibited a significantly high incidence of brain metastasis. We found that nicotine enhanced brain metastasis, while a depletion of microglia suppressed this effect in vivo. Nicotine skewed the polarity of microglia to the M2 phenotype, thereby increasing the secretion of IGF-1 and CCL20, which promoted tumor progression and stemness. Importantly, nicotine enhanced the expression of SIRPα in microglia and restricted their phagocytic ability. We also identified a compound, parthenolide, that suppressed brain metastasis by blocking M2 polarization. Our results indicate that nicotine promotes brain metastasis by skewing the polarity of M2 microglia, which enhances metastatic tumor growth. Our results also highlight a potential risk of using nicotine for tobacco cessation.

Efficacy of cognitive behavioural therapy-based smartphone app for smoking cessation in China: a study protocol of a randomised controlled trial

INTRODUCTION

A number of smartphone apps have been proved to be effective in assisting smoking cessation in many countries, but little is known about the effectiveness of smartphone apps that assist in smoking cessation in China. This study aims to evaluate the efficacy of cognitive behavioural therapy (CBT)-based cigarette smoking cessation smartphone app for treatment-seeking smokers in China.

METHODS AND ANALYSIS

In this remote control, randomised controlled trial, the participants will be randomised and allocated in 1:1 ratio to smoking cessation app intervention group or to control group. Participants will receive a 12-week intervention (treatment group will receive CBT-based cigarette smoking cessation smartphone app intervention and control group will receive text messaging-based control intervention) with follow-up at week 26. The primary outcome includes biologically verified continuous smoking abstinence at week 26 after the quit date. The main secondary outcomes include 7-hour point prevalence smoking abstinence at weeks 1, 2, 3, 4, 8, 12, 16, 20 and 26, self-reported continuous smoking abstinence at weeks 4, 8, 12, 16, 20 and 26 after the quit date. About 1200 smokers with willingness to make a quit attempt within a month from January 2021 to August 2021 or until the recruitment process is complete will be recruited. The final 26-week follow-up will be completed in August 2022. The trial results will be available by the end of 2022. All analyses will be done on an intention-to-treat basis. Based on the previous studies, we hypothesised that this CBT-based app will be an effective, feasible and accessible smoking cessation app in China.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the ethics committee of Sir Run Run Shaw Hospital, an affiliate of Zhejiang University, Medical College (number: 20200129-33). Study results will be disseminated via research conference presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT04421170.

Advances in biofeedback and neurofeedback studies on smoking

Smoking is a leading cause of morbidity and premature death constituting a global health challenge. Although, pharmacological and behavioral approaches comprise the mainstay of smoking cessation interventions, the efficacy and safety of pharmacotherapy is not demonstrated for some populations. Non-pharmacological approaches, such as biofeedback (BF) and neurofeedback (NF) could facilitate self-regulation of predisposing factors of relapse such as craving and stress. The current review aims to aggregate the existing evidence regarding the effects of BF and NF training on smokers. Relevant studies were identified through searching in Scopus, PubMed and Cochrane Library, and through hand-searching the references of screened articles. Peer-reviewed controlled and uncontrolled studies, where BF and/or NF training was administered, were included and evaluated according to PICOS framework. Narrative qualitative synthesis of ten eligible studies was performed, aggregated into three categories according to training provided. BF outcomes seem to be affected by smoking behavior prior to training; individualized EEG NF training holds promise for modulating craving-related response while minimizing the required number of sessions. Real-time fMRI NF studies concluded that nicotine-dependent individuals could modulate craving-related brain responses, while mixed results were revealed regarding smokers' ability to modulate brain responses related to resistance towards the urge to smoke. BF and NF training seem to facilitate modulation of autonomous and/or central nervous system activity while also transferring this learned self-regulation to behavioral outcomes. BF and NF training should a) address remaining issues on specificity and scientific validity, b) target diverse demographics, and c) produce robust reproducible methodologies and clinical guidelines for relevant health care providers, in order to be considered as viable complementary tools to standard smoking cessation care.

Transcranial Direct Current Stimulation Applied to the Dorsolateral and Ventromedial Prefrontal Cortices in Smokers Modifies Cognitive Circuits Implicated in the Nicotine Withdrawal Syndrome

BACKGROUND

The nicotine withdrawal syndrome remains a major impediment to smoking cessation. Cognitive and affective disturbances are associated with altered connectivity within and between the executive control network, default mode network (DMN), and salience network. We hypothesized that functional activity in cognitive control networks, and downstream amygdala circuits, would be modified by application of transcranial direct current stimulation (tDCS) to the left (L) dorsolateral prefrontal cortex (dlPFC, executive control network) and right (R) ventromedial prefrontal cortex (vmPFC, DMN).

METHODS

A total of 15 smokers (7 women) and 28 matched nonsmokers (14 women) participated in a randomized, sham-controlled, double-blind, exploratory crossover study of 3 tDCS conditions: anodal-(L)dlPFC/cathodal-(R)vmPFC, reversed polarity, and sham. Cognitive tasks probed withdrawal-related constructs (error monitoring, working memory, amygdalar reactivity), while simultaneous functional magnetic resonance imaging measured brain activity. We assessed tDCS impact on trait (nonsmokers vs. sated smokers) and state (sated vs. abstinent) smoking aspects.

RESULTS

Single-session, anodal-(L)dlPFC/cathodal-(R)vmPFC tDCS enhanced deactivation of DMN nodes during the working memory task and strengthened anterior cingulate cortex activity during the error-monitoring task. Smokers were more responsive to tDCS-induced DMN deactivation when sated (vs. withdrawn) and displayed greater cingulate activity during error monitoring than nonsmokers. Nicotine withdrawal reduced task engagement and attention and reduced suppression of DMN nodes.

CONCLUSIONS

Cognitive circuit dysregulation associated with nicotine withdrawal may be modifiable by anodal tDCS applied to L-dlPFC and cathodal tDCS applied to R-vmPFC. tDCS may have stronger effects as a complement to existing therapies, such as nicotine replacement, owing to possible enhanced plasticity in the sated state.

Association of tobacco and alcohol consumption with cardiovascular risk factors among elderly population in India

Introduction:

The present study was conducted to assess the association of tobacco and alcohol consumption with cardiovascular risk factors among elderly population living at high altitude regions of India.

Materials and Methods:

A cross-sectional study was conducted among 1003 elderly people living in district Nainital, Uttarakhand state, India. Thirty subjects were identified from 30 villages using population proportionate to size sampling methodology. The data on the consumption of tobacco and alcohol, mini nutritional assessment, Barthel activities of daily living scale, height, weight, blood pressure, fasting blood sugar, triglycerides, and total cholesterol was collected.

Results:

We found that smoking tobacco was associated with high cholesterol, lower body mass index, and low nutritional status (all, P < 0.05). Elderly subjects who consumed alcohol had 1.56 times higher risk of having high fasting blood glucose.

Conclusions:

Consumption of tobacco and alcohol increased the risk of cardiovascular diseases among elderly subjects. There is a need to improve these modifiable health behaviors through targeted educational and rehabilitation programs.

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

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

The Longitudinal Relationships between Depression and Smoking in Hardcore Smokers Using Autoregressive Cross-Lagged Modeling

PURPOSE

This study aimed to identify the directionality of the causal relationship and interaction between depression and amount of smoking over time in hardcore smokers using longitudinal descriptive analysis.

METHODS

Secondary data from the Korean Welfare Panel Study were analyzed using autoregressive cross-lagged modeling. Participants included 342 hardcore smokers who participated in the 8th to 11th waves of the panel study.

RESULTS

Analyses revealed that change(s) in depression levels according to time had a significant positive relationship with the total amount of smoking per day (β=.29, β=.19, β=.17, p<.001), while change(s) in total amount of smoking per day according to time had a significant positive relationship with depression (β=.43, β=.50, β=.38, p<.001). Analysis of the cross-lagged effect between depression and total amount of smoking per day showed that depression at one time point had a significantly positive relationship with the total amount of smoking per day at the next time point (β=.14, β=.13, β=.13, p=.021), and that the total amount of smoking per day at one time point had a significant positive relationship with depression at the next time point (β=.04, β=.04, β=.03, p=.044).

CONCLUSION

The findings in the present study confirmed a cross-interaction between depression and total amount of smoking per day in hardcore smokers. The present findings could be used to develop appropriate smoking-related interventions.

The Effects of Smoking Abstinence on Incentivized Spatial Working Memory

BACKGROUND AND OBJECTIVE

Reward processing and working memory (WM) underlie value-based decision-making; consequently, joint examination of these systems may further our understanding of why smokers choose to smoke again following a quit attempt (relapse). While previous studies have demonstrated altered reward and WM function associated with nicotine exposure, little is known about the effects of abstinence on the joint function of these systems. The current study aims to address this gap.

METHOD

Eighteen daily smokers were tested on a monetarily incentivized memory guided saccade (MGS) task on two separate, counterbalanced occasions, an abstinent and a non-abstinent session. The MGS task is a widely used metric of spatial working memory and enables precise quantification of the effects of rewards and nicotine exposure on behavior.

RESULTS

During the non-abstinent session, participants showed increased accuracy of the initial saccade towards the remembered target location on reward vs. neutral trials. Participants also showed increased accuracy of the final saccade towards the target, across incentive types, only during the non-abstinent condition.

DISCUSSION AND CONCLUSIONS

Our observation that rewards improve the accuracy of the initial memory guided saccade during the non-abstinent but not abstinent condition extends a growing literature indicating reduced motivation towards monetary rewards during abstinence. Further, differences in the accuracy of the final corrective saccade during the non-abstinent but not the abstinent condition suggests smoking abstinence-related effects on WM precision beyond those related to incentive motivation (e.g., sustained attention).

SIGNIFICANCE

This work extends our fundamental understanding of smoking's effects on core affective and cognitive processes.

Smokers and ex-smokers have shared differences in the neural substrates for potential monetary gains and losses

Despite an increased understanding of nicotine addiction, there is a scarcity of research comparing the neural correlates of non-drug reward between smokers and ex-smokers. Long-term changes in reward-related brain functioning for non-drug incentives may elucidate patterns of functioning that potentially contribute to ongoing smoking behaviour in current smokers. Similarly, examining the effects of previous chronic nicotine exposure during a period of extended abstinence may reveal whether there are neural correlates responsible for non-drug reward processing that are different from current smokers. The current study, therefore, sets out to examine the neural correlates of reward and loss anticipation, and their respective outcomes, in smokers, ex-smokers and matched controls using a monetary incentive delay task during functional magnetic resonance imaging. Here, we report that in the absence of any significant behavioural group differences, both smokers and ex-smokers showed a significantly greater activation change in the lateral orbitofrontal/anterior insular cortex compared with smokers when anticipating both potential monetary gains and losses. We further report that ex-smokers showed a significantly greater activation change in the ventral putamen compared with both controls and smokers and in the caudate compared with controls during the anticipation of potential monetary losses only. The results suggest that smoking may sensitize striato-orbitofrontal circuitry subserving motivational processes for loss avoidance and reward gain in nicotine addiction.

Stress and Addiction: When a Robust Stress Response Indicates Resiliency

OBJECTIVE

Stress reactivity research has traditionally focused on the idea that exaggerated responses to stress may have adverse effects on health. Accumulating evidence suggests that attenuated responses to stress and delayed recovery may also be problematic.

METHODS

This review focuses on the role of the stress response of the hypothalamic-pituitary-adrenocortical axis, the endogenous opioid system, and the cardiovascular system in hypertension, pain perception, and addictive behaviors. Results from multiple methods of assessment and stress paradigms conducted in our laboratory over the past two decades are integrated with research from other investigators and with existing theories.

RESULTS

Research indicates that exaggerated biological and physiological responses to stress and attenuated pain perception are associated with hypertension and risk for cardiovascular diseases. This research complements work linking reduced stress responses with enhanced pain sensitivity and discomfort. Multiple studies have also demonstrated that an attenuated stress response is linked to exacerbation of withdrawal symptoms and relapse in nicotine addiction. Evidence indicates important moderators (i.e., sex, personality traits, and early life adversity) and hypothalamic-pituitary-adrenocortical- and endogenous opioid system-related mechanisms in the altered response to stress. I integrate these findings in a conceptual model emphasizing that robust stress responses in the context of addiction and relapse should be considered as a marker of resiliency.

CONCLUSIONS

A blunted stress response may indicate long-term physiological dysregulation that could usher harmful consequences for cardiovascular disease, pain perception, and addictive disorders. The impact of dysregulation is influenced by multiple individual and situational factors that should be considered in evaluating the clinical significance of stress response dysregulation.

Smoking and Socio-demographic correlates of BMI

BACKGROUND

The aim of the current study was to examine the associations between Body Mass Index (BMI) and socio-demographic factors and to examine the relationship between BMI, smoking status and ethnicity.

METHODS

The Singapore Mental Health Study (SMHS) surveyed Singapore Residents (Singapore Citizens and Permanent Residents) aged 18 years old and above. BMI was calculated using height and weight which were self-reported by respondents. Socio-demographic characteristics and smoking status were recorded in a standardized data collection form.

RESULTS

Six thousand and six hundred sixteen respondents completed the study (response rate of 75.9 %) which constituted a representative sample of the adult resident population in Singapore. Ethnicity, gender and education status were associated with obesity. There was an interaction effect between ethnicity smoking status, and BMI. Indian and Malay smokers were less likely to be obese compared to Chinese smokers. The relationship between ethnicity and BMI was thus reversed when smoking was taken into account.

CONCLUSIONS

The study identified certain subgroups and risk factors that are associated with obesity. There is a need for further research to explore and identify genetic, metabolic and ethnic differences that underlie the interaction between ethnicity and smoking status which affects BMI.

The separate and combined effects of monoamine oxidase A inhibition and nicotine on resting state EEG

While nicotine is often associated with the neuropsychological effects of tobacco smoke, the robust monoamine oxidase (MAO) inhibition observed in chronic smokers is also likely to play a role. Electroencephalographically-indexed alterations in baseline neural oscillations by nicotine have previously been reported in both smokers and non-smokers, however, little is known about the effects of MAO inhibition in combination with nicotine on resting state EEG. In a sample of 24 healthy non-smoking males, the effects of 6 mg nicotine gum, as well as MAO-A inhibition via 75 mg moclobemide, were investigated in separate and combined conditions over four separate test sessions. Drug effects were observed in the alpha2, beta2, and theta band frequencies. Nicotine increased alpha2 power, and moclobemide decreased beta2 power. Theta power was decreased most robustly by the combination of both drugs. Therefore, this study demonstrated that the nicotinic and MAO inhibiting properties of tobacco may differentially influence fast-wave oscillations (alpha2 and beta2), while acting in synergy to influence theta oscillations.

Perceived stress and smoking-related behaviors and symptomatology in male and female smokers

INTRODUCTION

Stress has been found to be a significant risk factor for cigarette smoking. Stress affects males and females differently, as does the use of smoking for stress reduction. Few studies have examined gender differences with the interrelation of perceived stress and smoking behaviors and nicotine related symptomatology. Our study investigates this association, as well as the influence of sociodemographic variables.

METHODS

This is a retrospective analysis of 62 smokers (41 males, 21 females) enrolled in a smoking cessation study. At the screening visit sociodemographic information, smoking behaviors and survey measures were completed. These included the Perceived Stress Scale (PSS), Minnesota Nicotine Withdrawal Scale (MNWS), and others. Analyses were conducted using multiple linear regression models.

RESULTS

PSS score was found to have a negative association with number of cigarettes smoked in males (slope -0.29±0.08; p=0.0009) and females (slope -0.20±0.18; p=0.26) with no difference in effect between genders (p=0.64). Linear regression of MNWS on PSS revealed a positive association for both males (slope 0.41±0.068; p<0.0001) and females (slope 0.73±0.14; p<0.0001). There was a significant difference in effect between genders (p=0.04).

CONCLUSIONS

A strong positive association was observed between perceived stress and nicotine withdrawal symptomatology in smokers of both sexes, with a larger effect seen in women. These findings emphasize the importance of stress reduction in smokers, which may lead to fewer withdrawal symptoms and more effective smoking cessation.

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

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

Altered human brain anatomy in chronic smokers: a review of magnetic resonance imaging studies

Cigarette smoking is becoming more prevalent in developing countries, such as China, and is the largest single cause of preventable death worldwide. New emerging reports are highlighting how chronic cigarette smoking plays a role in neural dysfunctions, such as cognitive decline. Basic animal experimental studies have shown that rats undergo persistent pathological brain changes after being given chronic levels of nicotine. What is perhaps less appreciated is the fact that chronic cigarette smoking induces subtle anatomical changes in the human brain. Consequently, this chapter aims to summarize and integrate the existing magnetic resonance imaging studies on both gray- and white-matter marcostructural and microstructural changes. The reviewed studies demonstrate that chronic cigarette smoking results in discrete and localized alterations in brain region tissue (both the gray and white matter of different brain regions), which may, in part, be responsible for different neural dysfunctions. In addition, we further discuss the possible pathological and neurobiological mechanisms of these nicotinic effects on the brain tissue. We will also address the limitations of the current studies on this issue and identify opportunities for future research.

Dissociation of tolerance and nicotine withdrawal-associated deficits in contextual fear

Nicotine addiction is associated with the development of tolerance and the emergence of withdrawal symptoms upon cessation of chronic nicotine administration. Changes in cognition, including deficits in learning, are one of the most common withdrawal symptoms reported by smokers. However, the neural substrates of tolerance to the effects of nicotine on learning and the substrates of withdrawal deficits in learning are unknown, and in fact it is unclear whether a common mechanism is involved in both. The present study tested the hypothesis that tolerance and withdrawal are separate processes and that nicotinic acetylcholine receptor (nAChR) upregulation underlies changes in learning associated with withdrawal but not tolerance. C57BL/6 male mice were administered a dose of nicotine (3, 6.3, 12, or 24 mg/kg/d) chronically for varying days and tested for the onset of tolerance to the effects of nicotine on learning. Follow up experiments examined the number of days of chronic nicotine treatment required to produce withdrawal deficits in learning and a significant increase in [(3)H] epibatidine binding in the hippocampus indicative of receptor upregulation. The results indicate that tolerance onset was influenced by dose of chronic nicotine, that tolerance occurred before withdrawal deficits in learning emerged, and that nAChR upregulation in the dorsal hippocampus was associated with withdrawal but not tolerance. This suggests that for the effects of nicotine on learning, tolerance and withdrawal involve different substrates. These findings are discussed in terms of implications for development of therapeutics that target symptoms of nicotine addiction and for theories of addiction.

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

RATIONALE

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Adolescence is a period of development characterized by short- and long-term vulnerability to the rewarding effects of nicotine and reduced sensitivity to the anorectic effects of this drug

This study compared nicotine intake and changes in food intake and weight gain in naïve adolescent, naïve adult, and adult rats that were exposed to nicotine during adolescence. An extended intravenous self-administration (IVSA) model was used whereby rats had 23-hour access to saline or increasing doses of nicotine (0.03, 0.06, and 0.09 mg/kg/0.1 mL infusion) for 4-day intervals separated by 3-day periods of abstinence. Rats began IVSA as adolescents (PND 32-34) or adults (PND 75). A separate group of rats was exposed to nicotine via osmotic pumps (4.7 mg/kg) for 14 days during adolescence and then began nicotine IVSA as adults (PND 75). The rats that completed the nicotine IVSA regimen were also tested for nicotine-seeking behavior during extinction. The results revealed that nicotine intake was highest in adolescents followed by adults that were pre-exposed to nicotine during adolescence as compared to naïve adults. A similar pattern of nicotine-seeking behavior was observed during extinction. In contrast to nicotine intake, naïve adults displayed robust appetite and weight suppressant effects of nicotine, an effect that was absent in adolescents and adults that were pre-exposed to nicotine during adolescence. Our findings suggest that adolescence is a unique period of enhanced vulnerability to the reinforcing effects of nicotine. Although adolescents gain weight faster than adults, the food intake and weight suppressant effects of nicotine are reduced during adolescence. Importantly, our findings suggest that adolescent nicotine exposure produces long-lasting consequences that enhance nicotine reward and promote tolerance to the anorectic effects of this drug.

Greater risk sensitivity of dorsolateral prefrontal cortex in young smokers than in nonsmokers

RATIONALE

Despite a national reduction in the prevalence of cigarette smoking, ~19% of the adult US population persists in this behavior, with the highest prevalence among 18-25-year-olds. Given that the choice to smoke imposes a known health risk, clarification of brain function related to decision-making, particularly involving risk-taking, in smokers may inform prevention and smoking cessation strategies.

OBJECTIVES

This study aimed to compare brain function related to decision-making in young smokers and nonsmokers.

METHODS

The Balloon Analogue Risk Task (BART) is a computerized risky decision-making task in which participants pump virtual balloons, each pump associated with an incremental increase in potential payoff on a given trial but also with greater risk of balloon explosion and loss of payoff. We used this task to compare brain activation associated with risky decision-making in smokers (n = 18) and nonsmokers (n = 25), while they performed the BART during functional magnetic resonance imaging (fMRI). The participants were young men and women, 17-21 years of age.

RESULTS

Risk level (number of pumps) modulated brain activation in the right dorsolateral and ventrolateral prefrontal cortices more in smokers than in nonsmokers, and smoking severity (Heaviness of Smoking Index) was positively related to this modulation in an adjacent frontal region.

CONCLUSIONS

Given evidence for involvement of the right dorsolateral and ventrolateral prefrontal cortices in inhibitory control, these findings suggest that young smokers have a different contribution of prefrontal cortical substrates to risky decision-making than nonsmokers. Future studies are warranted to determine whether the observed neurobiological differences precede or result from smoking.

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.

Aggression, impulsivity, and psychopathic traits in combined antisocial personality disorder and substance use disorder

Aggression, impulsivity, and psychopathic traits are prominent in both antisocial personality disorder (ASPD) and substance use disorders (SUD), but have rarely been examined collectively. The authors' results show that all three variables were elevated in adults with comorbid ASPD/SUD, relative to SUD-only and control subjects.

Nicotine, Auditory Sensory Memory, and sustained Attention in a Human Ketamine Model of Schizophrenia: Moderating Influence of a Hallucinatory Trait

BACKGROUND

The procognitive actions of the nicotinic acetylcholine receptor (nAChR) agonist nicotine are believed, in part, to motivate the excessive cigarette smoking in schizophrenia, a disorder associated with deficits in multiple cognitive domains, including low-level auditory sensory processes and higher-order attention-dependent operations.

OBJECTIVES

As N-methyl-d-aspartate receptor (NMDAR) hypofunction has been shown to contribute to these cognitive impairments, the primary aims of this healthy volunteer study were to: (a) to shed light on the separate and interactive roles of nAChR and NMDAR systems in the modulation of auditory sensory memory (and sustained attention), as indexed by the auditory event-related brain potential - mismatch negativity (MMN), and (b) to examine how these effects are moderated by a predisposition to auditory hallucinations/delusions (HD).

METHODS

In a randomized, double-blind, placebo-controlled design involving a low intravenous dose of ketamine (0.04 mg/kg) and a 4 mg dose of nicotine gum, MMN, and performance on a rapid visual information processing (RVIP) task of sustained attention were examined in 24 healthy controls psychometrically stratified as being lower (L-HD, n = 12) or higher (H-HD) for HD propensity.

RESULTS

Ketamine significantly slowed MMN, and reduced MMN in H-HD, with amplitude attenuation being blocked by the co-administration of nicotine. Nicotine significantly enhanced response speed [reaction time (RT)] and accuracy (increased % hits and d' and reduced false alarms) on the RVIP, with improved performance accuracy being prevented when nicotine was administered with ketamine. Both % hits and d', as well as RT were poorer in H-HD (vs. L-HD) and while hit rate and d' was increased by nicotine in H-HD, RT was slowed by ketamine in L-HD.

CONCLUSIONS

Nicotine alleviated ketamine-induced sensory memory impairment and improved attention, particularly in individuals prone to HD.

Effects of the combination of metyrapone and oxazepam on intravenous nicotine self-administration in rats

RATIONALE

Despite increased education regarding its dangers, cigarette smoking remains a significant public health concern due to serious associated health consequences such as cancer and respiratory and cardiovascular diseases. Most smokers fail in their attempts to quit smoking, and current pharmacological interventions have relatively low levels of efficacy and are associated with significant adverse events. We have previously reported that combinations of metyrapone and oxazepam, administered at doses that were ineffective when delivered singly, resulted in dose-related decreases in cocaine self-administration in rats while not affecting food-maintained responding during the same sessions.

OBJECTIVES

The current study was designed to test the effects of the administration of a metyrapone:oxazepam combination on nicotine self-administration in rats.

METHODS

Several dose combinations of metyrapone (12.5, 25 or 50 mg/kg) and oxazepam (5 or 10 mg/kg) were tested in rats trained to intravenously (IV) self-administer nicotine (0.03 mg/kg/infusion) during 1-h self-administration sessions using both fixed-ratio and progressive-ratio (PR) schedules of reinforcement.

RESULTS

The administration of low doses of metyrapone and oxazepam in combination significantly decreased IV nicotine self-administration in rats. At the lowest doses of 12.5 mg/kg of metyrapone and 5 mg/kg of oxazepam, the drugs alone did not decrease IV nicotine self-administration, but the combination was effective. Varenicline was also tested using the fixed-ratio schedule, and reductions in nicotine intake were similar to those seen with the moderate dose of the combination.

CONCLUSIONS

The results of this study suggest a potential utility of the combination of metyrapone and oxazepam for smoking cessation in humans.

Cigarette smoking might impair memory and sleep quality

Although nicotine can enhance some cognitive functions, cigarette smoking may impair memory and sleep quality. Our aim was to investigate the impact of cigarette smoking on memory and sleep quality in healthy smokers. Sixty-eight healthy participants (34 smokers and 34 controls) completed the Wechsler Memory Scale-Revised and a Chinese version of the Pittsburgh Sleep Quality Index. The Wilcoxon signed ranks test was performed, and Hochberg's Sharpened Bonferroni correction was applied for multiple comparisons. The results show that current smokers had a worse visual memory compared to nonsmokers. There was no significant correlation between the index of Wechsler Memory Scale-Revised and Fagerström test for nicotine dependence. Moreover, smokers had poorer sleep quality. Cigarette smoking might impair memory and adversely influence sleep quality.

Bilateral fronto-parietal integrity in young chronic cigarette smokers: a diffusion tensor imaging study

BACKGROUND

Cigarette smoking continues to be the leading cause of preventable morbidity and mortality in China and other countries. Previous studies have demonstrated gray matter loss in chronic smokers. However, only a few studies assessed the changes of white matter integrity in this group. Based on those previous reports of alterations in white matter integrity in smokers, the aim of this study was to examine the alteration of white matter integrity in a large, well-matched sample of chronic smokers and non-smokers.

METHODOLOGY/PRINCIPAL FINDINGS

Using in vivo diffusion tensor imaging (DTI) to measure the differences of whole-brain white matter integrity between 44 chronic smoking subjects (mean age, 28.0±5.6 years) and 44 healthy age- and sex-matched comparison non-smoking volunteers (mean age, 26.3±5.8 years). DTI was performed on a 3-Tesla Siemens scanner (Allegra; Siemens Medical System). The data revealed that smokers had higher fractional anisotropy (FA) than healthy non-smokers in almost symmetrically bilateral fronto-parietal tracts consisting of a major white matter pathway, the superior longitudinal fasciculus (SLF).

CONCLUSION/SIGNIFICANCE

We found the almost symmetrically bilateral fronto-parietal whiter matter changes in a relatively large sample of chronic smokers. These findings support the hypothesis that chronic cigarette smoking involves alterations of bilateral fronto-parietal connectivity.

Biological mechanisms underlying the relationship between stress and smoking: state of the science and directions for future work

Theories of addiction implicate stress as a crucial mechanism underlying initiation, maintenance, and relapse to cigarette smoking. Examinations of the biological stress systems, including functioning of the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS), have provided additional insights into the relationship between stress and smoking. To date, convergent data suggests that chronic cigarette smoking is associated with alterations in HPA and ANS functioning; however, less is known about the role of HPA and ANS functioning in smoking initiation and relapse following cessation. In order to organize existing findings and stimulate future research, the current paper summarizes the available literature on the roles of HPA axis and ANS functioning in the relationship between stress and cigarette smoking, highlights limitations within the existing literature, and suggests directions for future research to address unanswered questions in the extant literature on the biological mechanisms underlying the relationship between stress and smoking.

Positive reactions to tobacco predict relapse after cessation

Among chronic smokers, individual differences in subjective reactions to smoking may characterize important facets of nicotine dependence that relate to abstinence-induced craving, withdrawal symptom profiles, and risk for relapse. Although the negative reinforcing properties of smoking have achieved prominent positions in models of relapse (Baker, Brandon, & Chassin, 2004), vulnerability to relapse risk may also arise from seeking positive reinforcement from smoking (Shiffman & Kirchner, 2009). In this study, 183 cessation-motivated smokers provided subjective craving, positive and negative reactions to standardized cigarettes following overnight abstinence. Level of craving, negative mood, and positive mood after overnight abstinence were significantly predictive of withdrawal on quit-day. Increased positive reactions to smoking were uniquely predictive of relapse after quitting (Hazard Ratio = 1.22, p < .001). Individual differences in positive reactions to smoking may be important markers of neurobiological systems that promote dependence and interfere with cessation efforts.

Associations between pain and current smoking status among cancer patients

There is growing empirical and clinical interest in purported associations between smoking and the aggravation of cancer symptoms and treatment side effects, such as pain. Both pain and smoking are highly prevalent among persons with cancer, and there is recent evidence to suggest that cancer patients who continue to smoke despite their diagnosis experience greater pain than nonsmokers. Accordingly, the main goal of this cross-sectional study was to examine associations between multiple levels of smoking status and several pain-related outcomes among a sample of 224 cancer patients about to begin chemotherapy. Patients completed self-report measures of pain severity, pain-related distress, and pain-related interference, as well as a demographics questionnaire. Results indicated that persons who continued to smoke despite being diagnosed with cancer reported more severe pain than never smokers, F (2, 215)=3.47, p<.05. Current smokers also reported greater interference from pain than either former or never smokers, F (2, 215)=5.61, p<.01. Among former smokers, an inverse relation between pain severity and the number of years since quitting smoking was observed, r (104)=-.26, p<.01. These data suggest that continued smoking despite a cancer diagnosis is associated with greater pain severity and interference from pain; however, future research is warranted to determine the directionality of this relationship.

Differences in "bottom-up" and "top-down" neural activity in current and former cigarette smokers: Evidence for neural substrates which may promote nicotine abstinence through increased cognitive control

Drug-related stimuli, through conditioning, are thought to acquire incentive motivational properties that code possible reward availability and elicit an attentional bias, possibly through increased "bottom-up" neural processing. The processes underlying this attentional bias are considered important in the maintenance of addiction, and crucially, in relapse among substance users attempting to remain abstinent. Equally, impaired "top-down" cognitive control may impair the ability to restrain "bottom-up" pre-potent behaviours, such as drug use, following exposure to drug-related stimuli. Two experiments sought to identify the neural loci of bottom-up/top-down processing during fMRI. Experiment 1 utilised an attentional bias paradigm to examine the behavioural and neural responses to neutral, emotionally evocative and smoking-related cues in control (n=13), ex-smoking (n=10 - abstinent >12months) and smoking (n=13 - mean >6.5years of use) groups. Experiment 2 used a go/no-go paradigm to examine the neural correlates of motor response inhibition and error monitoring in the same sample. The results of Experiment 1 demonstrated that, across conditions, current smokers had significantly less neural activity in cortical but significantly more activity in subcortical areas compared to both controls and ex-smokers. Ex-smokers exhibited more neural activity than both control and smoker groups in prefrontal cortical regions. Similarly, Experiment 2 revealed that smokers had reduced neural activity in prefrontal cortical regions during motor response inhibition compared to controls while ex-smokers demonstrated greater neural activity in prefrontal cortical regions compared to both controls and smokers during error monitoring. The results reveal cortical and subcortical differences between current smokers and controls and a general pattern of increased prefrontal cortical activity in ex-smokers. These findings may suggest that elevated topdown control might be an important characteristic of successful abstinence in individuals formerly dependent on nicotine.

Zebrafish for the study of the biological effects of nicotine

INTRODUCTION

Zebrafish are emerging as a powerful animal model for studying the molecular and physiological effects of nicotine exposure. The zebrafish have many advantageous physical characteristics, including small size, high fecundity rates, and externally developing transparent embryos. When combined with a battery of molecular-genetic tools and behavioral assays, these attributes enable studies to be conducted that are not practical using traditional animal models.

METHODS

We reviewed the literature on the application of the zebrafish model as a preclinical model to study the biological effects of nicotine exposure.

RESULTS

The identified studies used zebrafish to examine the effects of nicotine exposure on early development, addiction, anxiety, and learning. The methods used included green fluorescent protein-labeled proteins to track in vivo nicotine-altered neuron development, nicotine-conditioned place preference, and locomotive sensitization linked with high-throughput molecular and genetic screens and behavioral models of learning and stress response to nicotine. Data are presented on the complete homology of all known human neural nicotinic acetylcholine receptors in zebrafish and on the biological similarity of human and zebrafish dopaminergic signaling.

CONCLUSIONS

Tobacco dependence remains a major health problem worldwide. Further understanding of the molecular effects of nicotine exposure and genetic contributions to dependence may lead to improvement in patient treatment strategies. While there are limitations to the use of zebrafish as a preclinical model, it should provide a valuable tool to complement existing model systems. The reviewed studies demonstrate the enormous opportunity zebrafish have to advance the science of nicotine and tobacco research.

A quantitative analysis of subjective, cognitive, and physiological manifestations of the acute tobacco abstinence syndrome

RATIONALE

Previous studies have documented the existence of signs and symptoms of the acute tobacco abstinence syndrome; however, less attention has been paid to quantifying the magnitude of these effects.

OBJECTIVE

The present study quantified the relative magnitude of subjective, cognitive, and physiological manifestations of acute tobacco abstinence.

METHOD

Smokers (N=203, ≥ 15 cig/day) attended two counterbalanced laboratory sessions, one following 12-h of abstinence and the other following ad-lib smoking. At both sessions, they completed an extensive battery of self-report measures (withdrawal, affect, hunger, craving, subjective attentional bias towards smoking cues), physiological assessments (heart rate, blood pressure, brain EEG), and cognitive performance tasks (psychomotor processing, sustained attention, objective attentional bias).

RESULTS

Abstinence effects were largest for craving, subjective attentional bias, negative affect, overall withdrawal severity, concentration difficulty, hunger, and heart rate. Effects were moderate for positive affect and EEG power. Effects were small, but reliable, for psychomotor speed, sustained attention, and somatic symptoms. Effects on performance-based indices of attentional bias towards smoking-related cues were small and reliable for some indices but not others. Effects were small and inconsistent for blood pressure and EEG frequency. Variation in internal consistency accounted for 33% of the variation in abstinence effect sizes across measures.

CONCLUSIONS

There was a wide range of effect sizes both across and within domains, indicating that the acute tobacco abstinence syndrome is not a monotonic phenomenon. These findings may be indicative of the relative magnitudes of signs and symptoms that the average smoker may exhibit during acute abstinence.

Effects of expectancies and coping on pain-induced motivation to smoke

The prevalence of tobacco smoking among persons with recurrent pain is approximately twice that observed in the general population. Smoking has been associated with the development and exacerbation of several chronically painful conditions. Conversely, there is both experimental and cross-sectional evidence that pain is a potent motivator of smoking. A recent study provided the first evidence that laboratory-induced pain could elicit increased craving and produce shorter latencies to smoke (Ditre & Brandon, 2008). To further elucidate interrelations between pain and smoking, and to identify potential targets for intervention, in the current study, we tested whether several constructs derived from social-cognitive theory influence the causal pathway between pain and increased motivation to smoke. Smokers (N = 132) were randomly assigned to 1 of 4 conditions in this 2 x 2 between-subjects experimental design. Results indicated that manipulations designed to (a) challenge smoking-related outcome expectancies for pain reduction and (b) enhance pain-related coping produced decreased urge ratings and increased latencies to smoke, relative to controls. An unexpected interaction effect revealed that although each manipulation was sufficient to reduce smoking urges, the combination was neither additive nor synergistic. These findings were integrated with those of the extant literature to conceptualize and depict a causal pathway between pain and motivation to smoke as moderated by smoking-related outcome expectancies and mediated by the use of pain coping behaviors.

Effects of nicotine withdrawal on verbal working memory and associated brain response

Previous literature has reported effects of nicotine withdrawal on brain function during cognitive tasks such as verbal working memory (VWM). Mechanisms of these withdrawal effects have not been clearly identified. Functional neuroimaging offers an objective method to examine brain mechanisms associated with observable behavior and subjective reports. To investigate these mechanisms, 12 smokers were administered a 2-Back VWM challenge during two functional magnetic resonance imaging sessions. Participants abstained from smoking prior to both sessions; however, they applied a nicotine patch before one session and a placebo patch prior to the other. Among regions that exhibited a significant response to the 2-Back during either session, withdrawal was associated with significantly greater deactivation in left and right temporal poles and left medial frontal gyrus. The magnitude of task-related activation showed a significant inverse relationship to craving in the majority of regions during placebo administration. Also, individual brain responses varied more during placebo, suggesting inefficient neural processing. Results suggest that differences in brain response to a VWM challenge during abstinence may be attributed to increased craving. Further deactivation of regions associated with the default network (medial frontal and anterior temporal clusters) during the placebo condition suggests further suspension of default activity, possibly to compensate for inefficient neural processing.

Cognitive effects of nicotine: genetic moderators

Cigarette smoking is the main preventable cause of death in developed countries, and the development of more effective treatments is necessary. Cumulating evidence suggests that cognitive enhancement may contribute to the addictive actions of nicotine. Several studies have demonstrated that nicotine enhances cognitive performance in both smokers and non-smokers. Genetic studies support the role of both dopamine (DA) and nicotinic acetylcholine receptors (nAChRs) associated with nicotine-induced cognitive enhancement. Based on knockout mice studies, beta2 nAChRs are thought to be essential in mediating the cognitive effects of nicotine. alpha7nAChRs are associated with attentional and sensory filtering response, especially in schizophrenic individuals. Genetic variation in D2 type DA receptors and the catechol-O-methyltransferase enzyme appears to moderate cognitive deficits induced by smoking abstinence. Serotonin transporter (5-HTT) gene variation also moderates nicotine-induced improvement in spatial working memory. Less is known about the contribution of genetic variation in DA transporter and D4 type DA receptor genetic variation on the cognitive effects of nicotine. Future research will provide a clearer understanding of the mechanism underlying the cognitive-enhancing actions of nicotine.

Smoking reduces conflict-related anterior cingulate activity in abstinent cigarette smokers performing a Stroop task

Prior research suggests that abrupt initiation of abstinence from cigarette smoking reduces neural cognitive efficiency. When cognitive efficiency is high, processing speed and accuracy are maximized with minimal allocation of cognitive resources. The study presented here tested the effects of resumption of smoking on cognitive response conflict after overnight abstinence from smoking, hypothesizing that smoking would enhance cognitive efficiency. Twenty paid research volunteers who were chronic cigarette smokers abstained from smoking overnight (>12 h) before undergoing fMRI while performing a color-word Stroop task during two separate test sessions: one that did not include smoking before testing and another one that did. Statistical analyses were performed by modeling the Stroop effect (incongruent >congruent) BOLD response within a collection of a priori regions of interest that have consistently been associated with cognitive control. Behavioral assessment alone did not reveal any significant differences in the Stroop effect between the two sessions. BOLD activations, however, indicated that in the right anterior cingulate cortex (ACC), smokers had significantly less task-related activity following smoking (p<0.02). In contrast, the right middle frontal gyrus exhibited significantly greater activity after smoking as compared to the no-smoking session (p<0.003). Exaggerated neural activity in the ACC during nicotine withdrawal may reflect a compensatory mechanism by which cognitive control networks expend excessive energy to support selective attention processes. Resumption of smoking may enhance cognitive control in smokers, involving a reduction in ACC response conflict activity together with improvement in conflict resolution involving the dorsolateral prefrontal cortex.

Chronic nicotine exposure has dissociable behavioural effects on control and beta2-/- mice

Nicotine exerts beneficial effects on various neurological and psychiatric pathologies, yet its effects on cognitive performance remain unclear. Mice lacking the beta2 subunit of the nicotinic receptor (beta2-/-) show characteristic deficits in executive functions and are suggested as reliable animal models for some specific endophenotypes of human pathologies, notably ADHD. We use beta2-/- and their controls to investigate the consequences of chronic nicotine exposure on cognitive behaviour. We show that in control mice, this treatment elicits somewhat slight effects, particularly affecting nocturnal activity and self-grooming. By contrast, in beta2-/- mice, chronic nicotine treatment had restorative effects on exploratory behaviour in the open-field and affected rearing, but did not modify motor functions. We confirmed that beta2-/- mice exhibit impaired exploratory and social behaviour, and further demonstrated their nocturnal hyperactivity. These data support the proposal that beta2-/- mice represent a relevant model for cognitive disorders in humans and that nicotine administered chronically at low dose may relieve some of these.

Chronic cigarette smoking and the microstructural integrity of white matter in healthy adults: a diffusion tensor imaging study

Results from recent studies suggest that chronic cigarette smoking is associated with increased white matter volume in the brain as determined by in vivo neuroimaging. We used diffusion tensor imaging to examine the microstructural integrity of the white matter in 10 chronic smokers and 10 nonsmokers. All individuals were healthy, without histories of medical or psychiatric illness. Fractional anisotropy (FA) and trace were measured in the genu, body, and splenium of the corpus callosum. FA provides a measure of directional versus nondirectional water diffusion, whereas trace provides a measure of nondirectional water diffusion. Lower FA and higher trace values are considered to reflect less brain integrity. Voxel-based morphometry was used to define volumes in each of these regions of the corpus callosum. Chronic smokers exhibited significantly higher FA in the body and whole corpus callosum and a strong trend for higher FA in the splenium compared with nonsmokers. FA did not differ between groups in the genu, and neither trace nor white matter volumes differed between groups in any of the regions of interest. When subdivided by Fagerström score (low vs. high), the low Fagerström group exhibited significantly higher FA in the body of the corpus callosum compared with the high Fagerström group and the nonsmokers. These results suggest that, among healthy adults, lower exposure to cigarette smoking is associated with increased microstructural integrity of the white matter compared with either no exposure or higher exposure. Additional studies are needed to further explore differences in white matter integrity between smokers and nonsmokers.

Posttraumatic stress disorder and smoking relapse: A theoretical model

Posttraumatic stress disorder (PTSD) is associated with a high prevalence of cigarette smoking, heavy cigarette consumption, and low cessation rates. To date, little is known about mechanisms impeding smoking cessation among this recalcitrant group of smokers. An important first step in improving smoking cessation treatment efficacy is the assessment of knowledge about mechanisms pertinent to relapse. This theoretical study addresses the gap in the literature regarding factors potentially influencing smoking relapse among individuals with PTSD. Mechanisms reviewed that may be particularly relevant to smoking relapse among PTSD smokers include negative affect, positive affect, attention, anxiety sensitivity, distress tolerance, and self-efficacy. Treatment implications as well as methodological advances that may be relevant to examining the proposed relapse model are discussed.