What a difference a day makes: differences in initial abstinence response during a smoking cessation attempt

Individual variations in motives for nicotine self-administration in male rats: evidence in support for a precision psychopharmacology

The significant heterogeneity in smoking behavior among smokers, coupled with the inconsistent efficacy of approved smoking cessation therapies, supports the presence of individual variations in the mechanisms underlying smoking. This emphasizes the need to shift from standardized to personalized smoking cessation therapies. However, informed precision medicine demands precision fundamental research. Tobacco smoking is influenced and sustained by diverse psychopharmacological interactions between nicotine and environmental stimuli. In the classical experimental rodent model for studying tobacco dependence, namely intravenous self-administration of nicotine, seeking behavior is reinforced by the combined delivery of nicotine and a discrete cue (nicotine+cue). Whether self-administration behavior is driven by the same psychopharmacological mechanisms across individual rats remains unknown and unexplored. To address this, we employed behavioral pharmacology and unbiased cluster analysis to investigate individual differences in the mechanisms supporting classical intravenous nicotine self-administration (0.04 mg/kg/infusion) in male outbred Sprague-Dawley rats. Our analysis identified two clusters: one subset of rats sought nicotine primarily for its reinforcing effects, while the second subset sought nicotine to enhance the reinforcing effects of the discrete cue. Varenicline (1 mg/kg i.p.) reduced seeking behavior in the former group, whereas it tended to increase in the latter group. Crucially, despite this fundamental qualitative difference revealed by behavioral manipulation, the two clusters exhibited quantitatively identical nicotine+cue self-administration behavior. The traditional application of rodent models to study the reinforcing and addictive effects of nicotine may mask individual variability in the underlying motivational mechanisms. Accounting for this variability could significantly enhance the predictive validity of translational research.

Synthetic contraceptive hormones occlude the ability of nicotine to reduce ethanol consumption in ovary-intact female rats

Rates of tobacco and alcohol use in women are rising, and women are more vulnerable than men to escalating tobacco and alcohol use. Many women use hormonal birth control, with the oral contraceptive pill being the most prevalent. Oral contraceptives contain both a progestin (synthetic progesterone) and a synthetic estrogen (ethinyl estradiol; EE) and are contraindicated for women over 35 years who smoke. Despite this, no studies have examined how synthetic contraceptive hormones impact this pattern of polysubstance use in females. To address this critical gap in the field, we treated ovary-intact female rats with either sesame oil (vehicle), the progestin levonorgestrel (LEVO; contained in formulations such as Alesse®), or the combination of EE+LEVO in addition to either undergoing single (nicotine or saline) or polydrug (nicotine and ethanol; EtOH) self-administration (SA) in a sequential use model. Rats preferred EtOH over water following extended EtOH drinking experience as well as after nicotine or saline SA experience, and rats undergoing only nicotine SA (water controls) consumed more nicotine as compared to rats co-using EtOH and nicotine. Importantly, this effect was occluded in groups treated with contraceptive hormones. In the sequential use group, both LEVO alone and the EE+LEVO combination occluded the ability of nicotine to decrease EtOH consumption. Interestingly, demand experiments suggest an economic substitute effect between nicotine and EtOH. Together, we show that chronic synthetic hormone exposure impacts nicotine and EtOH sequential use, demonstrating the crucial need to understand how chronic use of different contraceptive formulations alter patterns of polydrug use in women.

Is self-reported 7-day point prevalence abstinence an useful measure for smoking cessation effectiveness among individuals with mental disorders?

Smoking rates among individuals with mental disorders are higher compared to general population. We aimed to investigate the effectiveness of a smoking cessation treatment among individuals with and without mental disorders. Self-report 7-day point prevalence was used to assess abstinence status among 'intention to treat' (n = 1,213) and 'completers-only' (n = 578) samples. Participants were distributed in (1) ND-only; (2) ND and other substance use disorder (ND-SUD); (3) ND associated with mental disorder but no other SUD (ND-MD); and (4) co-morbid ND, SUD and MD (ND-SUMD). The treatment program was composed by six weeks of group Cognitive Behavioral Therapy (CBT) and medical consultations. Multivariate logistic regression models were applied. Rates of abstinence between ND-only and both ND-MD and ND-SUMD differed in the 'intention-to-treat' sample, with the former group showing the best rate (62.5%, 48% and 45.4% respectively). ND-SUD had the second-best rate of abstinence (56.1%). Differences between groups were not observed among 'completers-only'. Self-report 7-day point prevalence abstinence is economical and reliable to be used in low to middle-income countries. In this study, it showed that the 6-week smoking cessation treatment had a positive effect among completers, which supports the importance of investing in treatment to decrease smoking prevalence in this population.

Different doses, durations and modes of delivery of nicotine replacement therapy for smoking cessation

BACKGROUND

Nicotine replacement therapy (NRT) aims to replace nicotine from cigarettes. This helps to reduce cravings and withdrawal symptoms, and ease the transition from cigarette smoking to complete abstinence. Although there is high-certainty evidence that NRT is effective for achieving long-term smoking abstinence, it is unclear whether different forms, doses, durations of treatment or timing of use impacts its effects.

OBJECTIVES

To determine the effectiveness and safety of different forms, deliveries, doses, durations and schedules of NRT, for achieving long-term smoking cessation.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group trials register for papers mentioning NRT in the title, abstract or keywords, most recently in April 2022.

SELECTION CRITERIA

We included randomised trials in people motivated to quit, comparing one type of NRT use with another. We excluded studies that did not assess cessation as an outcome, with follow-up of fewer than six months, and with additional intervention components not matched between arms. Separate reviews cover studies comparing NRT to control, or to other pharmacotherapies.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods. We measured smoking abstinence after at least six months, using the most rigorous definition available. We extracted data on cardiac adverse events (AEs), serious adverse events (SAEs) and study withdrawals due to treatment.  MAIN RESULTS: We identified 68 completed studies with 43,327 participants, five of which are new to this update. Most completed studies recruited adults either from the community or from healthcare clinics. We judged 28 of the 68 studies to be at high risk of bias. Restricting the analysis only to those studies at low or unclear risk of bias did not significantly alter results for any comparisons apart from the preloading comparison, which tested the effect of using NRT prior to quit day whilst still smoking.  There is high-certainty evidence that combination NRT (fast-acting form plus patch) results in higher long-term quit rates than single form (risk ratio (RR) 1.27, 95% confidence interval (CI) 1.17 to 1.37; I2 = 12%; 16 studies, 12,169 participants). Moderate-certainty evidence, limited by imprecision, indicates that 42/44 mg patches are as effective as 21/22 mg (24-hour) patches (RR 1.09, 95% CI 0.93 to 1.29; I2 = 38%; 5 studies, 1655 participants), and that 21 mg patches are more effective than 14 mg (24-hour) patches (RR 1.48, 95% CI 1.06 to 2.08; 1 study, 537 participants). Moderate-certainty evidence, again limited by imprecision, also suggests a benefit of 25 mg over 15 mg (16-hour) patches, but the lower limit of the CI encompassed no difference (RR 1.19, 95% CI 1.00 to 1.41; I2 = 0%; 3 studies, 3446 participants). Nine studies tested the effect of using NRT prior to quit day (preloading) in comparison to using it from quit day onward. There was moderate-certainty evidence, limited by risk of bias, of a favourable effect of preloading on abstinence (RR 1.25, 95% CI 1.08 to 1.44; I2 = 0%; 9 studies, 4395 participants). High-certainty evidence from eight studies suggests that using either a form of fast-acting NRT or a nicotine patch results in similar long-term quit rates (RR 0.90, 95% CI 0.77 to 1.05; I2 = 0%; 8 studies, 3319 participants). We found no clear evidence of an effect of duration of nicotine patch use (low-certainty evidence); duration of combination NRT use (low- and very low-certainty evidence); or fast-acting NRT type (very low-certainty evidence). Cardiac AEs, SAEs and withdrawals due to treatment were all measured variably and infrequently across studies, resulting in low- or very low-certainty evidence for all comparisons. Most comparisons found no clear evidence of an effect on these outcomes, and rates were low overall. More withdrawals due to treatment were reported in people using nasal spray compared to patches in one study (RR 3.47, 95% CI 1.15 to 10.46; 1 study, 922 participants; very low-certainty evidence) and in people using 42/44 mg patches in comparison to 21/22 mg patches across two studies (RR 4.99, 95% CI 1.60 to 15.50; I2 = 0%; 2 studies, 544 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

There is high-certainty evidence that using combination NRT versus single-form NRT and 4 mg versus 2 mg nicotine gum can result in an increase in the chances of successfully stopping smoking. Due to imprecision, evidence was of moderate certainty for patch dose comparisons. There is some indication that the lower-dose nicotine patches and gum may be less effective than higher-dose products. Using a fast-acting form of NRT, such as gum or lozenge, resulted in similar quit rates to nicotine patches. There is moderate-certainty evidence that using NRT before quitting may improve quit rates versus using it from quit date only; however, further research is needed to ensure the robustness of this finding. Evidence for the comparative safety and tolerability of different types of NRT use is limited. New studies should ensure that AEs, SAEs and withdrawals due to treatment are reported.

Pathophysiology of nAChRs: limbic circuits and related disorders

Human epidemiological studies have identified links between nicotine intake and stress disorders, including anxiety, depression and PTSD. Here we review the clinical evidence for activation and desensitization of nicotinic acetylcholine receptors (nAChRs) relevant to affective disorders. We go on to describe clinical and preclinical pharmacological studies suggesting that nAChR function may be involved in the etiology of anxiety and depressive disorders, may be relevant targets for medication development, and may contribute to the antidepressant efficacy of non-nicotinic therapeutics. We then review what is known about nAChR function in a subset of limbic system areas (amygdala, hippocampus and prefrontal cortex), and how this contributes to stress-relevant behaviors in preclinical models that may be relevant to human affective disorders. Taken together, the preclinical and clinical literature point to a clear role for ACh signaling through nAChRs in regulation of behavioral responses to stress. Disruption of nAChR homeostasis is likely to contribute to the psychopathology observed in anxiety and depressive disorders. Targeting specific nAChRs may therefore be a strategy for medication development to treat these disorders or to augment the efficacy of current therapeutics.

Anhedonia in tobacco withdrawal among African-American smokers

Anhedonia-diminished interest and pleasure in response to rewards-may be a symptom of tobacco withdrawal that is understudied in priority populations. This experiment investigated the magnitude and correlates of various dimensions of anhedonia during tobacco withdrawal among African-American (AA) smokers-a population subject to health disparities. AA smokers (N = 607; ≥ 10 cigarettes/day, 37.8% female, M[SD] age = 50.0[10.6] years) completed self-report measures assessing expected pleasure from (i.e., consummatory anhedonia) and desire to engage in (i.e., anticipatory anhedonia) various types of hypothetically experienced rewards at counterbalanced 16-hr tobacco deprived and nondeprived lab visits. Other tobacco withdrawal symptom measures (e.g., craving, negative affect, hunger) were also assessed. Tobacco deprivation most robustly increased scores on a composite measure of consummatory anhedonia directed toward various reward domains (i.e., hobbies, sensory experiences, social activities; d = .32, p < .001). Deprivation modestly increased consummatory and anticipatory anhedonia directed toward sexual rewards (ds = .09-.12, ps < .02), did not significantly change anhedonia toward food rewards, and decreased anhedonia directed toward psychoactive drug rewards (i.e., increased desire for and pleasure from drugs; ds = -.21 to -.19, ps < .001). Deprivation-induced changes in anhedonia were modestly correlated with other withdrawal symptoms (average |r|s = .04-.23) and were amplified among participants with higher nicotine dependence and lower positive affect-related traits (|β|s = .10-.12, ps < .01). Some dimensions of anhedonia may be genuine expressions of acute tobacco withdrawal in AA smokers. Applying multi-dimensional anhedonia conceptualizations might advance basic knowledge and treatment of tobacco use disorder, improve smoking cessation outcomes, and address tobacco-related health disparities facing AA smokers. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Motives for Substance Use in Daily Life: A Systematic Review of Studies Using Ecological Momentary Assessment

The motivational model of substance use posits four motive subtypes (coping, enhancement, social, conformity) dynamically interact with contextual factors to impact decisions about substance use. Yet, prior studies assessing the motivational model have relied on between-person, cross-sectional evaluations of trait motives. We systematically reviewed ecological momentary assessments (EMA) studies (N=64) on motives for substance use to examine: methodological features of EMA studies examining the motivational model, support for the motivational model between and within individuals, and associations between trait motives and daily processes. Results of the reviewed studies provide equivocal support for the motivational model, and suggest that EMA measures and trait measures of motives might not reflect the same construct. The reviewed body of research indicates most studies have not examined the momentary and dynamic nature of the motivational model and more research is needed to inform interventions that address heterogeneous reasons for substance use in daily life.

The Effect of Breathing Exercise on Nicotine Withdrawal Symptoms, Cigarette Cravings, and Affect

The aim of this study was to evaluate the effects of a single bout of controlled deep breathing and a "three-part breathing" exercise on nicotine withdrawal symptoms, cigarette cravings, and affect. A secondary aim was to determine whether autonomic nervous system activity mediates these effects. Twenty-four participants attended one practical session followed by three intervention sessions on 3 separate days: control condition, controlled deep breathing, and three-part breathing. Participants were asked to abstain from smoking for 15 hours before intervention. Nicotine withdrawal symptoms, cigarette cravings, affect, and heart rate variability were assessed preintervention and again on four occasions postintervention: immediately postintervention and every 10 minutes on three more occasions. Results revealed that the three-part breathing exercise resulted in lower negative affect scores relative to control condition and controlled deep breathing immediately after postintervention (p < .05). In addition, high-frequency heart rate variability score was significantly reduced throughout the 30-minute session.

Interactions between reproductive transitions during aging and addiction: promoting translational crosstalk between different fields of research

Discovery of neural mechanisms underlying neuropsychiatric disorders within the aging and addiction fields has been a main focus of the National Institutes of Health. However, there is a dearth of knowledge regarding the biological interactions of aging and addiction, which may have important influences on progression of disease and treatment outcomes in aging individuals with a history of chronic drug use. Thus, there is a large gap in these fields of research, which has slowed progress in understanding and treating substance use disorders (SUDs) as well as age-related diseases, specifically in women who experience precipitous reproductive cycle transitions during aging. The goal of this review is to highlight overlap of SUDs and age-related processes with a specific focus on menopause and smoking, and identify critical gaps. We have narrowed the focus of the review to smoking, as the majority of findings on hormonal and aging influences on drug use have come from this area of research. Further, we highlight female-specific issues such as transitional menopause and exogenous estrogen use. These issues may impact drug use cessation as well as outcomes with aging and age-related neurodegenerative diseases in women. We first review clinical studies for smoking, normal aging, and pathological aging, and discuss the few aging-related studies taking smoking history into account. Conversely, we highlight the dearth of clinical smoking studies taking age as a biological variable into account. Preclinical and clinical literature show that aging, age-related pathological brain disease, and addiction engage overlapping neural mechanisms. We hypothesize that these putative drivers interact in meaningful ways that may exacerbate disease and hinder successful treatment outcomes in such comorbid populations. We highlight areas where preclinical studies are needed to uncover neural mechanisms in aging and addiction processes. Collectively, this review highlights the need for crosstalk between different fields of research to address medical complexities of older adults, and specifically women, who smoke.

Prediction of Smoking Abstinence in Women Living With Human Immunodeficiency Virus Infection

BACKGROUND

This study examined whether baseline negative emotional states (depression and anxiety) would predict craving for cigarettes and other nicotine withdrawal symptoms in early abstinence and whether those emotional states and withdrawal symptoms would predict failure in quitting smoking at 3 months postquit among U.S. women living with the human immunodeficiency virus (HIV).

METHOD

The study is a secondary analysis of data from two smoking cessation studies of women living with HIV. Craving for cigarettes and other withdrawal symptoms were assessed weekly with a total of 229 observations during the first 4 weeks following quit day. Descriptive statistics were used to examine baseline characteristics of the participants. A random growth curve model was used to estimate between-person differences in a within-person trend of changes in the withdrawal symptoms. A binary logistic regression analysis was performed to identify predictors of short-term smoking abstinence.

RESULTS

Baseline anxiety was a predictor of postquit nicotine withdrawal symptoms but baseline depression was not. Neither baseline anxiety nor depression predicted postquit craving for cigarettes. Participants who received an HIV-tailored smoking cessation intervention showed a greater decline in craving symptom than those who received an attention-controlled intervention. HIV-tailored intervention and less craving predicted smoking abstinence at 3-month follow-up.

DISCUSSION

Compared to an attention-controlled intervention, an HIV-tailored intervention effectively decreased craving for cigarette smoking after quitting-which effectively increased the rate of short-term smoking abstinence in women living with HIV.

Specific Relapse Predictors: Could Cognitive-Behavioral Treatment for Smoking Cessation Be Improved?

Relapse remains a frequent and complex phenomenon that is not yet well understood. An under-researched area of study that may provide relevant information concerns the assessment of specific post-treatment variables, rather than the composite measures commonly used to predict smoking relapse. The current study sought to examine the effects of post-treatment smoking-related variables, including withdrawal symptomatology, abstinence self-efficacy, and smoking urgency in negative-affect situations and smoking relapse at the 3 month follow-up. The sample comprised 130 participants who achieved abstinence for at least 24 h through a cognitive-behavioral smoking cessation treatment. Regression analysis was conducted for both composite measures and specific subscales and items. Data showed that composite measures of tobacco withdrawal, self-efficacy, and smoking urgency in negative-affect situations were not significant predictors of smoking relapse. However, the analysis including subscales, and specific items showed that lower self-efficacy in negative-affect-related situations (OR = 1.36) and three withdrawal symptoms—irritability/frustration/anger (OR = 2.99), restlessness/impatience (OR = 1.87), and craving (OR = 2.31)—were significant predictors of relapse. These findings offer new insights into the role of different smoking-related post-treatment variables in short-term relapse. Considering and specifically targeting these variables after achieving abstinence may potentially contribute to reducing smoking relapse.

Tobacco craving and withdrawal symptoms in psychiatric patients during a motivational enhancement intervention based on a 26-hour smoking abstinence period

INTRODUCTION

In psychiatric patients, tobacco withdrawal symptoms are frequently seen as a barrier to smoking cessation; however, further studies are warranted in this specific population.

METHODS

Patients receiving in- or out-patient mental health care participated in a motivational enhancement program including a 26-hour tobacco abstinence experience with professional support and optional nicotine replacement therapy. The study included 174 subjects, of whom 159 were evaluated 1 week before and at the end of the 26-hour abstinence period. Repeated assessments included the Minnesota Nicotine Tobacco Withdrawal Scale Revised (MNWS-R), two items of the Mood and Physical Symptoms Scale (MPSS) regarding craving, the State-Trait Anxiety Inventory (STAI-S), the Beck Depression Inventory (BDI-21), and the World Health Organization Well-Being Index (WHO-5).

RESULTS

More than half the participants (52.3%) succeeded in 26-hour smoking abstinence. Craving was the most frequent MNWS-R withdrawal symptom (28.3% scored ≥3 on a 0–4 scale). Comparison of pre- and post-intervention data revealed significant improvements in 13 of 16 MNWS-R symptoms as well as craving (MPSS) and well-being, and significant decreases in anxiety and depression. Increasing MNWS-R craving scores and greater depression were both significantly associated with lower success in the 26-hour smoking abstinence period.

CONCLUSIONS

The negative effects of tobacco withdrawal symptoms in psychiatric patients may be substantially overestimated. Participation in a supportive structured motivational intervention with a 26-hour smoking cessation experience was well tolerated and contributed to temporary improvements in mental state. Craving is an interesting symptom to evaluate during smoking cessation attempts.

Factors associated with abstinence after a recent smoking cessation attempt across 28 European Union member states

INTRODUCTION

There is a lack of information regarding factors associated with successful smoking cessation on a population and European Union (EU)-wide level. Our study seeks to explore individual and country-level factors associated with abstinence after a recent smoking cessation attempt across the EU.

METHODS

We obtained data from the March 2017 Special Eurobarometer 87.1 (n=27901). Regression analysis was performed on a subset of 1472 individuals who made quit attempts in the past 12 months. Sociodemographic, policy and country-level factors were assessed using logistic regression among smokers and ex-smokers who attempted to quit approximately 12 months before the survey date. We defined and examined the Cessation Ratio (ratio of number of recent quitters to those who did not succeed) across 28 EU Member States.

RESULTS

In all, 14.9% (n=1018) of current smokers and 8.80% (n=454) of ex-smokers attempted to quit in approximately the last 12 months (n=1472). Cessation Ratios ranged from 0.182 (95% CI: 0.045–0.319) in Estonia to 1.060 (95% CI: 0.262–1.860) in Sweden. There is a quadratic, U-shaped relationship between odds of quitting and smoking prevalence. The lowest odds of cessation were observed at a prevalence of 26.3%, with higher odds of cessation observed above and below this point. Respondents who reported financial difficulties were less likely to quit (AOR=0.66; 95% CI: 0.52–0.83). There was no association of likelihood of success with other sociodemographic factors or the Tobacco Control Scale treatment score.

CONCLUSIONS

These findings highlight a need for exploring reasons behind the variation in likelihood of abstinence following a recent quit attempt, in order to design policies targeted at population groups or countries that need greater support.

N-acetylcysteine yields sex-specific efficacy for cue-induced reinstatement of nicotine seeking

Women report greater craving during certain phases of the menstrual cycle. As well, research indicates that pharmacotherapies for smoking may be less efficacious in women compared with men, which may be due to interactions with natural fluctuations in ovarian hormone levels. N-Acetylcysteine (NAC) is a glutamatergic compound that has shown some efficacy in treating substance use disorders and aids in the prevention of relapse. However, it is unclear whether NAC has sex-specific effectiveness for nicotine relapse treatment. Given that NAC has shown promise to reduce nicotine reinstatement in preclinical models using male rats, the exploration of potential sex differences in the efficacy of NAC is warranted. Using a rat model, we first investigated the ability of NAC treatment (100 mg/kg, ip) during nicotine withdrawal with extinction training to reduce cue-induced nicotine seeking in male and female rats. Next, we assessed whether NAC's effects were estrous cycle-dependent for female rats. Results show that following NAC treatment during extinction, reinstatement of nicotine seeking was significantly decreased in males but not females, indicating a sex-specific effect of NAC. Furthermore, for females, both vehicle- and NAC-treated groups significantly reinstated nicotine-seeking behavior compared with extinction, regardless of estrous cycle phase. These results suggest that NAC is inefficacious in reducing nicotine relapse in females regardless of estrous cycle phase at the dose evaluated here. These collective findings could have important clinical implications for use and efficacy of NAC as a pharmacotherapy for freely cycling women smokers.

Different doses, durations and modes of delivery of nicotine replacement therapy for smoking cessation

BACKGROUND

Nicotine replacement therapy (NRT) aims to replace nicotine from cigarettes to ease the transition from cigarette smoking to abstinence. It works by reducing the intensity of craving and withdrawal symptoms. Although there is clear evidence that NRT used after smoking cessation is effective, it is unclear whether higher doses, longer durations of treatment, or using NRT before cessation add to its effectiveness.

OBJECTIVES

To determine the effectiveness and safety of different forms, deliveries, doses, durations and schedules of NRT, for achieving long-term smoking cessation, compared to one another.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group trials register, and trial registries for papers mentioning NRT in the title, abstract or keywords. Date of most recent search: April 2018.

SELECTION CRITERIA

Randomized trials in people motivated to quit, comparing one type of NRT use with another. We excluded trials that did not assess cessation as an outcome, with follow-up less than six months, and with additional intervention components not matched between arms. Trials comparing NRT to control, and trials comparing NRT to other pharmacotherapies, are covered elsewhere.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods. Smoking abstinence was measured after at least six months, using the most rigorous definition available. We extracted data on cardiac adverse events (AEs), serious adverse events (SAEs), and study withdrawals due to treatment. We calculated the risk ratio (RR) and the 95% confidence interval (CI) for each outcome for each study, where possible. We grouped eligible studies according to the type of comparison. We carried out meta-analyses where appropriate, using a Mantel-Haenszel fixed-effect model.

MAIN RESULTS

We identified 63 trials with 41,509 participants. Most recruited adults either from the community or from healthcare clinics. People enrolled in the studies typically smoked at least 15 cigarettes a day. We judged 24 of the 63 studies to be at high risk of bias, but restricting the analysis only to those studies at low or unclear risk of bias did not significantly alter results, apart from in the case of the preloading comparison. There is high-certainty evidence that combination NRT (fast-acting form + patch) results in higher long-term quit rates than single form (RR 1.25, 95% CI 1.15 to 1.36, 14 studies, 11,356 participants; I² = 4%). Moderate-certainty evidence, limited by imprecision, indicates that 42/44 mg are as effective as 21/22 mg (24-hour) patches (RR 1.09, 95% CI 0.93 to 1.29, 5 studies, 1655 participants; I² = 38%), and that 21 mg are more effective than 14 mg (24-hour) patches (RR 1.48, 95% CI 1.06 to 2.08, 1 study, 537 participants). Moderate-certainty evidence (again limited by imprecision) also suggests a benefit of 25 mg over 15 mg (16-hour) patches, but the lower limit of the CI encompassed no difference (RR 1.19, 95% CI 1.00 to 1.41, 3 studies, 3446 participants; I² = 0%). Five studies comparing 4 mg gum to 2 mg gum found a benefit of the higher dose (RR 1.43, 95% CI 1.12 to 1.83, 5 studies, 856 participants; I² = 63%); however, results of a subgroup analysis suggest that only smokers who are highly dependent may benefit. Nine studies tested the effect of using NRT prior to quit day (preloading) in comparison to using it from quit day onward; there was moderate-certainty evidence, limited by risk of bias, of a favourable effect of preloading on abstinence (RR 1.25, 95% CI 1.08 to 1.44, 9 studies, 4395 participants; I² = 0%). High-certainty evidence from eight studies suggests that using either a form of fast-acting NRT or a nicotine patch results in similar long-term quit rates (RR 0.90, 95% CI 0.77 to 1.05, 8 studies, 3319 participants; I² = 0%). We found no evidence of an effect of duration of nicotine patch use (low-certainty evidence); 16-hour versus 24-hour daily patch use; duration of combination NRT use (low- and very low-certainty evidence); tapering of patch dose versus abrupt patch cessation; fast-acting NRT type (very low-certainty evidence); duration of nicotine gum use; ad lib versus fixed dosing of fast-acting NRT; free versus purchased NRT; length of provision of free NRT; ceasing versus continuing patch use on lapse; and participant- versus clinician-selected NRT. However, in most cases these findings are based on very low- or low-certainty evidence, and are the findings from single studies.AEs, SAEs and withdrawals due to treatment were all measured variably and infrequently across studies, resulting in low- or very low-certainty evidence for all comparisons. Most comparisons found no evidence of an effect on cardiac AEs, SAEs or withdrawals. Rates of these were low overall. Significantly more withdrawals due to treatment were reported in participants using nasal spray in comparison to patch in one trial (RR 3.47, 95% CI 1.15 to 10.46, 922 participants; very low certainty) and in participants using 42/44 mg patches in comparison to 21/22 mg patches across two trials (RR 4.99, 95% CI 1.60 to 15.50, 2 studies, 544 participants; I² = 0%; low certainty).

AUTHORS' CONCLUSIONS

There is high-certainty evidence that using combination NRT versus single-form NRT, and 4 mg versus 2 mg nicotine gum, can increase the chances of successfully stopping smoking. For patch dose comparisons, evidence was of moderate certainty, due to imprecision. Twenty-one mg patches resulted in higher quit rates than 14 mg (24-hour) patches, and using 25 mg patches resulted in higher quit rates than using 15 mg (16-hour) patches, although in the latter case the CI included one. There was no clear evidence of superiority for 42/44 mg over 21/22 mg (24-hour) patches. Using a fast-acting form of NRT, such as gum or lozenge, resulted in similar quit rates to nicotine patches. There is moderate-certainty evidence that using NRT prior to quitting may improve quit rates versus using it from quit date only; however, further research is needed to ensure the robustness of this finding. Evidence for the comparative safety and tolerability of different types of NRT use is of low and very low certainty. New studies should ensure that AEs, SAEs and withdrawals due to treatment are both measured and reported.

Addiction, Anhedonia, and Comorbid Mood Disorder. A Narrative Review

Background: Recently, anhedonia has been recognized as an important Research Domain Criterion (RDoC) by the National Institute of Mental Health. Anhedonia is proposed to play an essential role in the pathogenies of both addictive and mood disorders, and possibly their co-occurrence with a single individual. However, up to now, comprehensive information about anhedonia concerning its underlying neurobiological circuitries, the neurocognitive correlates, and their role in addiction, mood disorder, and comorbidity remains scarce. Aim: In this literature review of human studies, we bring together the current state of knowledge with respect to anhedonia in its relationship with disorders in the use of substances (DUS) and the comorbidity with mood disorders. Method: A PubMed search was conducted using the following search terms: (Anhedonia OR Reward Deficiency) AND ((Drug Dependence OR Abuse) OR Alcohol OR Nicotine OR Addiction OR Gambling OR (Internet Gaming)). Thirty-two articles were included in the review. Results: Anhedonia is associated with substance use disorders, and their severity is especially prominent in DUS with comorbid depression. Anhedonia may be both a trait and a state dimension in its relation to DUS and tends to impact DUS treatment outcome negatively.

Evaluating the effect of smoking cessation treatment on a complex dynamical system

OBJECTIVE

To understand the dynamic relations among tobacco withdrawal symptoms to inform the development of effective smoking cessation treatments. Dynamical system models from control engineering are introduced and utilized to evaluate complex treatment effects. We demonstrate how dynamical models can be used to examine how distinct withdrawal-related processes are related over time and how treatment influences these relations.

METHOD

Intensive longitudinal data from a randomized placebo-controlled smoking cessation trial (N=1504) are used to estimate a dynamical model of withdrawal-related processes including momentary craving, negative affect, quitting self-efficacy, and cessation fatigue for each of six treatment conditions (nicotine patch, nicotine lozenge, bupropion, patch + lozenge, bupropion + lozenge, and placebo).

RESULTS

Estimation and simulation results show that (1) withdrawal measurements are interrelated over time, (2) nicotine patch + nicotine lozenge showed reduced cessation fatigue and enhanced self-efficacy in the long-term while bupropion + nicotine lozenge was more effective at reducing negative affect and craving, and (3) although nicotine patch + nicotine lozenge had a better initial effect on cessation fatigue and self-efficacy, nicotine lozenge had a stronger effect on negative affect and nicotine patch had a stronger impact on craving.

CONCLUSIONS

This approach can be used to provide new evidence illustrating (a) the total impact of treatment conditions (via steady state values) and (b) the total initial impact (via rate of initial change values) on smoking-related outcomes for separate treatment conditions, noting that the conditions that produce the largest change may be different than the conditions that produce the fastest change.