Investigating tobacco withdrawal in response to reduced nicotine cigarettes among smokers with opioid use disorder and other vulnerabilities

Epigenetic embedding of childhood adversity: mitochondrial metabolism and neurobiology of stress-related CNS diseases

This invited article ad memoriam of Bruce McEwen discusses emerging epigenetic mechanisms underlying the long and winding road from adverse childhood experiences to adult physiology and brain functions. The conceptual framework that we pursue suggest multidimensional biological pathways for the rapid regulation of neuroplasticity that utilize rapid non-genomic mechanisms of epigenetic programming of gene expression and modulation of metabolic function via mitochondrial metabolism. The current article also highlights how applying computational tools can foster the translation of basic neuroscience discoveries for the development of novel treatment models for mental illnesses, such as depression to slow the clinical manifestation of Alzheimer's disease. Citing an expression that many of us heard from Bruce, while "It is not possible to roll back the clock," deeper understanding of the biological pathways and mechanisms through which stress produces a lifelong vulnerability to altered mitochondrial metabolism can provide a path for compensatory neuroplasticity. The newest findings emerging from this mechanistic framework are among the latest topics we had the good fortune to discuss with Bruce the day before his sudden illness when walking to a restaurant in a surprisingly warm evening that preluded the snowstorm on December 18th, 2019. With this article, we wish to celebrate Bruce's untouched love for Neuroscience.

Tobacco endgame and priority populations: a scoping review

AIM

To summarise the research literature on the impacts or perceptions of policies to end tobacco use at a population level (ie, tobacco endgame policies) among people from eight priority population groups (experiencing mental illness, substance use disorders, HIV, homelessness, unemployment or low incomes, who identify as lesbian, gay, bisexual, transgender, queer or intersex (LGBTQI+) or who have experienced incarceration).

METHODS

Guided by JBI Scoping Review Methodology, we searched six databases for original research examining the impacts or perceptions of 12 tobacco endgame policies among eight priority populations published since 2000. We report the results according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews checklist.

RESULTS

Of the 18 included studies, one described perceptions of five endgame policies among people on low incomes in Aotearoa (New Zealand), and 17 focused on the effectiveness or impacts of a very low nicotine content (VLNC) cigarette standard among people experiencing mental illness (n=14), substance use disorders (n=8), low incomes (n=6), unemployment (n=1) or who identify as LGBTQI+ (n=1) in the USA. These studies provide evidence that VLNC cigarettes can reduce tobacco smoking, cigarette cravings, nicotine withdrawal and nicotine dependence among these populations.

CONCLUSIONS

Most of the tobacco endgame literature related to these priority populations focuses on VLNC cigarettes. Identified research gaps include the effectiveness of endgame policies for reducing smoking, impacts (both expected and unexpected) and policy perceptions among these priority populations.

Effects of very low nicotine content cigarettes on smoking across vulnerable populations

There has been long-standing interest in a reduced-nicotine product standard for combusted tobacco, which is within the regulatory purview of the Food and Drug Administration (FDA). In weighing whether to establish this standard, it is important to consider potential responses among people who are at elevated risk for tobacco-related health harms. In this narrative review, we summarize studies of very low nicotine content (VLNC) cigarettes conducted between 2010 and 2021 in groups that the FDA has identified as vulnerable populations. Studies conducted to date in adults with mental health conditions, adults with opioid use disorder, socioeconomically-disadvantaged adults, and youth or young adults indicate that immediate switching to VLNC cigarettes decreases smoking, with minimal or no unintended negative consequences. Few studies have investigated the effects of VLNC cigarettes in racial or ethnic minorities, people who smoke menthol cigarettes, and pregnant women, but initial findings suggest that responses of these individuals are similar to responses observed in other vulnerable populations. We are not aware of studies that have investigated VLNC cigarettes in military/veteran populations, sexual or gender minority individuals, or people living in underserved rural environments. Future research directions include understanding how to promote cessation in the context of a reduced-nicotine standard, and how to correct VLNC misperceptions in vulnerable populations. Nevertheless, the evidence to date indicates that a reduced-nicotine standard is likely to have the same beneficial effects on smoking reductions as it does in less vulnerable populations, which should provide some confidence in pursuing this regulatory approach.

Nicotine and opioid co-dependence: Findings from bench research to clinical trials

Concomitant use of tobacco and opioids represents a growing public health concern. In fact, the mortality rate due to smoking-related illness approaches 50% among SUD patients. Cumulative evidence demonstrates that the vulnerability to drugs of abuse is influenced by behavioral, environmental, and genetic factors. This review explores the contribution of genetics and neural mechanisms influencing nicotine and opioid reward, respiration, and antinociception, emphasizing the interaction of cholinergic and opioid receptor systems. Despite the substantial evidence demonstrating nicotine-opioid interactions within the brain and on behavior, the currently available pharmacotherapies targeting these systems have shown limited efficacy for smoking cessation on opioid-maintained smokers. Thus, further studies designed to identify novel targets modulating both nicotinic and opioid receptor systems may lead to more efficacious approaches for co-morbid nicotine dependence and opioid use disorder.

Association of depression symptom level with smoking urges, cigarette withdrawal, and smoking reinstatement: A preliminary laboratory study

BACKGROUND

Cigarette smoking urges, withdrawal, and smoking reinstatement may be especially relevant to people with elevated depression symptoms who smoke. This laboratory study aimed to assess relations between depression symptom level and smoking urges for reward and relief, cigarette withdrawal, and smoking reinstatement in people who smoke cigarettes daily during acute abstinence and while smoking as usual.

METHODS

Participants with low (n = 51) or elevated (n = 29) baseline depression symptoms underwent two counterbalanced laboratory sessions (i.e., abstinent, non-abstinent). At each session, they completed subjective measures of smoking urges for reward and relief, and withdrawal. They also completed a laboratory smoking reinstatement task measuring whether they would delay smoking and the number of cigarettes smoked.

RESULTS

The elevated depression symptom group reported significantly higher withdrawal (p = .01) and smoked more cigarettes than the low depression symptoms group during the smoking reinstatement task self-administration period at the abstinent session (p = .04). Smoking urges for reward and relief were not significantly different by depression symptom group. There were no significant interactions of depression and abstinence with any outcomes.

CONCLUSIONS

As outcomes were measured at both an abstinent and non-abstinent session, findings identify factors for people with elevated depression symptoms who smoke which may drive smoking behavior and impede smoking cessation efforts. This study provides evidence that people with elevated depression symptoms who smoke may need additional/more pharmacological or behavioral smoking cessation aids targeted at reducing withdrawal and number of cigarettes smoked.

A review of the evidence on cigarettes with reduced addictiveness potential

Background

In May 2018, the Secretariat for the World Health Organization Framework Convention on Tobacco Control convened a meeting to discuss the potential for reducing the addictiveness of tobacco products. A central focus was to review research findings on the behavioral effects of reducing the addictiveness of cigarettes.

Methods

This manuscript reports the results of a review of the behavioral science literature, updated through April 2021, with special attention to both the potential benefits and unintended consequences of reducing nicotine in cigarettes.

Results

Available evidence suggests that reducing nicotine content in cigarettes to very low levels could benefit public health in three primary ways, by 1) decreasing uptake of regular smoking, 2) decreasing the amount people smoke, and 3) increasing the likelihood of smoking cessation. Current evidence also suggests that reducing nicotine in cigarettes may produce similar benefits across many important subpopulations of people who smoke, including those with psychiatric comorbidities, those who use other substances, those with low socioeconomic status, young people, people who smoke infrequently and people who prefer menthol cigarettes. Cigarette nicotine reduction could also lead to some undesirable outcomes, such as experiencing withdrawal, product manipulation, an illicit market, and harm misperceptions; strategies that may mitigate each are discussed.

Conclusion

Overall, behavioral research suggests product standards that limit the nicotine content of combusted tobacco products could render cigarettes and similar products less addictive. The availability of legal, non-combusted products that effectively substitute for cigarettes and the dissemination of public health campaigns that clarify misperceptions about the relationship between nicotine, tobacco and disease may facilitate the extent to which a nicotine reduction policy reduces smoking.