Targeting the noradrenergic system for gender-sensitive medication development for tobacco dependence

Brain dysfunctions and neurotoxicity induced by psychostimulants in experimental models and humans: an overview of recent findings

Preclinical and clinical studies indicate that psychostimulants, in addition to having abuse potential, may elicit brain dysfunctions and/or neurotoxic effects. Central toxicity induced by psychostimulants may pose serious health risks since the recreational use of these substances is on the rise among young people and adults. The present review provides an overview of recent research, conducted between 2018 and 2023, focusing on brain dysfunctions and neurotoxic effects elicited in experimental models and humans by amphetamine, cocaine, methamphetamine, 3,4-methylenedioxymethamphetamine, methylphenidate, caffeine, and nicotine. Detailed elucidation of factors and mechanisms that underlie psychostimulant-induced brain dysfunction and neurotoxicity is crucial for understanding the acute and enduring noxious brain effects that may occur in individuals who use psychostimulants for recreational and/or therapeutic purposes.

Therapeutics for Substance-Using Women: The Need to Elucidate Sex-Specific Targets for Better-Tailored Treatments

In the last decade, alcohol consumption in the US has risen by 84% in women compared with 35% in men. Furthermore, research has shown that sex- and gender-related differences may disadvantage women in terms of developing a range of psychological, cognitive, and medical problems considerably earlier in their drinking history than men, and despite consuming a similar quantity of substances. While this "telescoping" process has been acknowledged in the literature, a concomitant understanding of the underlying biobehavioral mechanisms, and an increase in the development of specific treatments tailored to women, has not occurred. In the current chapter we focus on understanding why the need for personalized, sex-specific medications is imperative, and highlight some of the potential sex-specific gonadal and stress-related adaptations underpinning the accelerated progress from controlled to compulsive drug and alcohol seeking in women. We additionally discuss the efficacy of these mechanisms as novel targets for medications development, using exogenous progesterone and guanfacine as examples. Finally, we assess some of the challenges faced and progress made in terms of developing innovative medications in women. We suggest that agents such as exogenous progesterone and adrenergic medications, such as guanfacine, may provide some efficacy in terms of attenuating stress-induced craving for several substances, as well as improving the ability to emotionally regulate in the face of stress, preferentially in women. However, to fully leverage the potential of these therapeutics in substance-using women, greater focus needs to the placed on reducing barriers to treatment and research by encouraging women into clinical trials.

Gender differences in the associations between tobacco smoke exposure and depressive symptoms among U.S. adults: NHANES 2007-2018

BACKGROUND

Findings concerning gender differences in the associations between tobacco smoke exposure (TSE) and depression are inconsistent. This study aimed to investigate the gender-specific associations between active and passive TSE with depressive symptoms in a large, nationally representative sample of U.S. adults.

METHODS

Data were from 27,175 adults aged ≥20 years in the 2007-2018 National Health and Nutrition Examination Survey (NHANES). Depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9). Multivariable logistic regression was used to adjust for possible confounders. Whether the TSE-depression relationships may differ by age, race/ethnicity, socioeconomic status, body mass index (BMI), and self-reported health status was examined.

RESULTS

After adjustment for lifestyle- and health-related variables, no significant associations between active (OR, 1.16 [95% CI, 0.87-1.55]) and passive TSE (OR, 0.84 [95% CI, 0.59-1.19]) and depressive symptoms were found among men. Among women, active TSE was associated with depressive symptoms (OR, 1.90 [95% CI, 1.51-2.39]), while the association for passive TSE was nonsignificant (OR, 1.11 [95% CI, 0.91-1.34]) after adjusting for lifestyle- and health-related variables. Interaction and subgroup analyses showed that self-reported health status could modify the relationship between passive TSE and depressive symptoms among women. Furthermore, a dose-response relationship between serum cotinine and depressive symptoms was found in women, but not in men.

CONCLUSIONS

This study suggests a stronger TSE-depression association in women than in men. Understanding these gender-specific patterns and identifying the potential moderators of such relationships will enable better targeting of public health interventions.

Gender Differences in Smoking Initiation and Cessation Associated with the Intergenerational Transfer of Smoking across Three Generations: The Nagahama Study

Global tobacco policies lowered overall and male smoking rates, but female smoking rates have remained unchanged. Parent-child studies revealed the effects of parental smoking, but gender differences had mixed results. We investigated the effects of long-term smoking behavior in families over three generations in order to clarify gender differences. A cross-sectional study in a community-based genome cohort was conducted using a self-reported questionnaire. A total of 8652 respondents were stratified by gender regarding smoking initiation. A logistic regression analysis was performed to analyze the family smoking history. A total of 2987 current smokers and ever-smokers were compared regarding smoking cessation. With respect to smoking initiation, women were affected by their smoking mothers (odds ratio (OR), 2.4; 95% confidence interval (CI), 1.8-3.2) and grandmothers (OR, 1.7; CI, 1.1-2.4). Women who continued smoking were affected only by their smoking mothers (OR, 1.6; CI, 1.05-2.49). In conclusion, gender differences in smoking initiation and cessation are possibly associated with family smoking history. Mothers and grandmothers were shown to have a strong influence on women with respect to both smoking initiation and cessation. Future research should focus on providing evidence for effective gender-specific intervention programs to curb long-term smoking in women.

Investigating sex differences and the effect of drug exposure order in the sensory reward-enhancing effects of nicotine and d-amphetamine alone and in combination

Nicotine enhances the rewarding effects of other environmental stimuli; this reward-enhancement encourages and maintains nicotine consumption. Nicotine use precedes other psychostimulant use, but receiving a stimulant prescription also predicts future smoking. Previously, no study has investigated effects of drug exposure order in reward-enhancement, nor with nicotine and d-amphetamine. Thus, we aimed to investigate how drug exposure order impacted the reward-enhancing effects of nicotine and d-amphetamine, alone and in combination. We used 20 male and 20 female Sprague-Dawley rats. Enhancement was investigated within-subjects by examining responding maintained by a visual stimulus reinforcer following a pre-session injection of either d-amphetamine (Sal, 0.1, 0.3, or 0.6 mg/kg) or nicotine (Sal, 0.03, 0.06, 0.1, 0.3 mg/kg). Twenty rats (10 M, 10 F) completed enhancement testing with nicotine before d-amphetamine. The other 20 rats (10 M, 10 F) completed testing with d-amphetamine before nicotine. Following these phases, rats were then given two pre-session injections: one of d-amphetamine (Sal, 0.1, 0.3, or 0.6 mg/kg) and another of nicotine (Sal, 0.03, 0.06, 0.1, or 0.3 mg/kg). Experiencing amphetamine before nicotine increased reward-enhancing effects of nicotine. Females exhibited greater effects of d-amphetamine on reward-enhancement, with no effect of exposure order. During the interaction phase, receiving nicotine before amphetamine enhanced the interaction between nicotine and d-amphetamine for females whereas amphetamine before nicotine heightened this interaction for males. From this, prior and current amphetamine use, in addition to sex, should be considered when treating nicotine dependency and when examining factors driving poly-substance use involving nicotine and d-amphetamine. Keywords: Adderall, ADHD, Dexedrine, operant, smoking, polysubstance use.

The effect of smoking on depressive symptoms

BACKGROUND

People who smoke tend to report higher levels of psychological distress than those who do not smoke. However, studies suggest that smoking reduces many sub-dimensions of distress, including depressive symptoms. A negative (i.e. depression reducing) effect of smoking on depressive symptoms might be observed in survey panel data only after adjustment for the effect of depressive symptoms on smoking. Results from analyses that make that adjustment are presented within groups jointly defined by race and gender, and for all respondents in a representative sample of the U.S.

POPULATION

METHOD

Reciprocal effects of smoking and depressive symptoms (DSx) are estimated with dynamic panel models. Data are from the Americans' Changing Lives study which assessed smoking and depressive symptoms five times over 25 years. Additional analyses provide estimates of effect of continuing to smoke versus quitting.

RESULTS

The estimated effect of smoking on DSx after adjustment for the simultaneous effect of DSx on smoking and unobserved confounders is negative among women. The estimated effect among men is not statistically significant, and no race difference is observed.

CONCLUSIONS

The tendency for smoking to reduce depressive symptoms among American women is masked in analyses that fail to account for the reciprocal effect of depressive symptoms on smoking.

Association of Tobacco Use During Pregnancy, Perceived Stress, and Depression Among Alaska Native Women Participants in the Healthy Pregnancies Project

INTRODUCTION

In general population samples, higher levels of stress and depression have been associated with increased prevalence of smoking in pregnancy. Little is known about the association of prenatal tobacco use, stress, and depression among American Indian or Alaska Native (AI/AN) women.

METHODS

The Healthy Pregnancies Project is a cluster-randomized controlled trial, evaluating a community-level intervention compared with usual care, for reducing tobacco use during pregnancy and postpartum among AN women in 16 villages in western Alaska. This cross-sectional study analyzed baseline data from enrolled pregnant women. Baseline measures included the self-reported, 7-day, point-prevalence current use of any tobacco, Perceived Stress Scale (PSS), and the Center for Epidemiological Studies-Depression (CES-D). Generalized estimating equations (GEE) analyses adjusted for village, participant age, and gestational age.

RESULTS

Participants (N = 352) were on average (SD) 25.8 (5.0) years of age and at 26.8 (9.8) weeks gestation. 66.5% were current tobacco users, of which 77% used Iqmik, a homemade form of smokeless tobacco. Compared with nonusers, tobacco users reported lower PSS score (p = .020) and less clinical levels of depression (CES-D ≥ 16) (18.1% vs. 9.3%, p = .21). Findings were not accounted for by nicotine dependence severity or self-reported tobacco use before pregnancy.

CONCLUSIONS

In this sample of pregnant AN women, tobacco users report less stress and clinical levels of depression than nonusers. A potential challenge with tobacco treatment for pregnant AN women is to provide alternative ways of deescalating stress and affect management instead of using tobacco.

IMPLICATIONS

This study contributes novel information on the association of tobacco use, perceived stress, and depression among Alaska Native women enrolled in a clinical trial to promote healthy pregnancies. Most prior studies addressing this topic were conducted among general population samples of pregnant women who smoked cigarettes. Little is known about these associations with prenatal smokeless tobacco, or among American Indian or Alaska Native women. The results are contrary to findings reported previously, because current tobacco use was associated with less stress and depression than nonuse. The study findings have implications for cessation treatment for this tobacco-use disparity group.

Effectiveness of transdermal nicotine patch in premenopausal female smokers is moderated by within-subject severity of negative affect and physical symptoms

RATIONALE

Nicotine patches may be less effective in female compared with male smokers. However, it is unknown if negative affect and physical symptoms influence transdermal nicotine patch-related effects on smoking behaviors.

METHODS

Eighty-one acutely tobacco-abstinent premenopausal female smokers attended three counter-balanced experimental sessions across the menstrual cycle (early follicular, late follicular, and mid-luteal) and were randomized to patch condition (nicotine [21 mg] vs. placebo [0 mg] transdermal patch). Negative affect and physical symptoms were assessed prior to patch administration. The patch was removed 5 h post-administration, and participants completed a smoking reinstatement task. Multilevel linear models tested associations of patch condition, negative affect and physical symptoms, and their interaction on smoking behavior.

RESULTS

There was a significant patch condition × Negative Affect and Pain symptoms interaction on the number of cigarettes smoked (p < 0.05). When Negative Affect and Pain were lower-than-usual, females administered a nicotine patch smoked significantly fewer cigarettes than females administered a placebo patch (p < .05), but there were no significant patch differences when Negative Affect and Pain were higher-than-usual. There was also a significant patch condition × Negative Affect interaction on time delay. The effects of patch condition on time delay to smoking were greater during sessions in which Negative Affect was higher-than-usual.

CONCLUSIONS

Results suggest that among female smokers transdermal nicotine patch effectiveness may interact with negative affect and pain. Understanding and considering female-specific factors that may impact the efficacy of one of the most commonly used cessation medications is important for improving smoking cessation in female smokers.

Stress Allostasis in Substance Use Disorders: Promise, Progress, and Emerging Priorities in Clinical Research

Clinicians and researchers alike have long believed that stressors play a pivotal etiologic role in risk, maintenance, and/or relapse of alcohol and other substance use disorders (SUDs). Numerous seminal and contemporary theories on SUD etiology posit that stressors may motivate drug use and that individuals who use drugs chronically may display altered responses to stressors. We use foundational basic stress biology research as a lens through which to evaluate critically the available evidence to support these key stress-SUD theses in humans. Additionally, we examine the field's success to date in targeting stressors and stress allostasis in treatments for SUDs. We conclude with our recommendations for how best to advance our understanding of the relationship between stressors and drug use, and we discuss clinical implications for treatment development.

Variability in nicotine conditioned place preference and stress-induced reinstatement in mice: Effects of sex, initial chamber preference, and guanfacine

Relapse to smoking occurs at higher rates in women compared with men, especially when triggered by stress. Studies suggest that sex-specific interactions between nicotine reward and stress contribute to these sex differences. Accordingly, novel treatment options targeting stress pathways, such as guanfacine, an α2-adrenergic receptor agonist, may provide sex-sensitive therapeutic effects. Preclinical studies are critical for elucidating neurobiological mechanisms of stress-induced relapse and potential therapies, but rodent models of nicotine addiction are often hindered by large behavioral variability. In this study, we used nicotine conditioned place preference to investigate stress-induced reinstatement of nicotine preference in male and female mice, and the effects of guanfacine on this behavior. Our results showed that overall, nicotine induced significant place preference acquisition and swim stress-induced reinstatement in both male and female mice, but with different nicotine dose-response patterns. In addition, we explored the variability in nicotine-dependent behaviors with median split analyses and found that initial chamber preference in each sex differentially accounted for variability in stress-induced reinstatement. In groups that showed significant stress-induced reinstatement, pretreatment with guanfacine attenuated this behavior. Finally, we evaluated neuronal activation by Arc immunoreactivity in the infralimbic cortex, prelimbic cortex, anterior insula, basolateral amygdala, lateral central amygdala and nucleus accumbens core and shell. Guanfacine induced sex-dependent changes in Arc immunoreactivity in the infralimbic cortex and anterior insula. This study demonstrates sex-dependent relationships between initial chamber preference and stress-induced reinstatement of nicotine conditioned place preference, and the effects of guanfacine on both behavior and neurobiological mechanisms.

Gender differences in subjective stress and neuroendocrine response to a stress task among individuals with opioid dependence: A pilot study

BACKGROUND

Opioid dependence is a significant public health problem in the United States and the number of opioid overdose deaths among women has increased dramatically in comparison to men in the last few years. In this context, understanding the biological mechanisms underlying gender differences in vulnerability to opioid dependence is essential.

METHODS

The current pilot study examined gender differences in subjective stress, heart rate (HR), and cortisol/dephydroepiandrosterone (DHEA) response to a laboratory stressor (Trier Social Stress Test; TSST) or a no-stress condition, and drug cue paradigm among men (n = 21) and women (n = 18) with opioid dependence.

RESULTS

Significant group (TSST vs. no stress) differences emerged in self-reported stress [F(1,35) = 23.8, p < .001], HR [F(1,31) = 12.3; p = .001] and cortisol (F1,34 = 5.0; p = .032) response, such that the TSST group was more reactive than the no-stress group. Women reported greater subjective stress [F(1,35) = 6.5, p <= .015] in response to the TSST compared to men. However, men evidenced marginally greater cortisol and DHEA responses to the TSST compared to women [F(1,34) = 2.7; p = .113 and F(1,31) = 3.4; p = .073, respectively].

CONCLUSIONS

Although women with opioid dependence reported greater subjective stress when exposed to a laboratory stress paradigm as compared to men, the neuroendocrine response was more robust in men. This pattern was similar to gender findings in men and women with cocaine and tobacco use disorders. The blunted cortisol combined with an increased subjective response among women may be a sign of HPA axis dysregulation which could increase vulnerability to relapse in women.

Neurobiological and Neurophysiological Mechanisms Underlying Nicotine Seeking and Smoking Relapse

Tobacco-related morbidity and mortality continue to be a significant public health concern. Unfortunately, current FDA-approved smoking cessation pharmacotherapies have limited efficacy and are associated with high rates of relapse. Therefore, a better understanding of the neurobiological and neurophysiological mechanisms that promote smoking relapse is needed to develop novel smoking cessation medications. Here, we review preclinical studies focused on identifying the neurotransmitter and neuromodulator systems that mediate nicotine relapse, often modeled in laboratory animals using the reinstatement paradigm, as well as the plasticity-dependent neurophysiological mechanisms that facilitate nicotine reinstatement. Particular emphasis is placed on how these neuroadaptations relate to smoking relapse in humans. We also highlight a number of important gaps in our understanding of the neural mechanisms underlying nicotine reinstatement and critical future directions, which may lead toward the development of novel, target pharmacotherapies for smoking cessation.

Sex differences in stress-related alcohol use

Rates of alcohol use disorder (AUD) have increased in women by 84% over the past ten years relative to a 35% increase in men. This substantive increase in female drinking is alarming given that women experience greater alcohol-related health consequences compared to men. Stress is strongly associated with all phases of alcohol addiction, including drinking initiation, maintenance, and relapse for both women and men, but plays an especially critical role for women. The purpose of the present narrative review is to highlight what is known about sex differences in the relationship between stress and drinking. The critical role stress reactivity and negative affect play in initiating and maintaining alcohol use in women is addressed, and the available evidence for sex differences in drinking for negative reinforcement as it relates to brain stress systems is presented. This review discusses the critical structures and neurotransmitters that may underlie sex differences in stress-related alcohol use (e.g., prefrontal cortex, amygdala, norepinephrine, corticotropin releasing factor, and dynorphin), the involvement of sex and stress in alcohol-induced neurodegeneration, and the role of ovarian hormones in stress-related drinking. Finally, the potential avenues for the development of sex-appropriate pharmacological and behavioral treatments for AUD are identified. Overall, women are generally more likely to drink to regulate negative affect and stress reactivity. Sex differences in the onset and maintenance of alcohol use begin to develop during adolescence, coinciding with exposure to early life stress. These factors continue to affect alcohol use into adulthood, when reduced responsivity to stress, increased affect-related psychiatric comorbidities and alcohol-induced neurodegeneration contribute to chronic and problematic alcohol use, particularly for women. However, current research is limited regarding the examination of sex in the initiation and maintenance of alcohol use. Probing brain stress systems and associated brain regions is an important future direction for developing sex-appropriate treatments to address the role of stress in AUD.

The role of stress in drug addiction. An integrative review

BACKGROUND

The high prevalence and burden to society of drug abuse and addiction is undisputed. However, its conceptualisation as a brain disease is controversial, and available interventions insufficient. Research on the role of stress in drug addiction may bridge positions and develop more effective interventions.

AIM

The aim of this paper is to integrate the most influential literature to date on the role of stress in drug addiction.

METHODS

A literature search was conducted of the core collections of Web of Science and Semantic Scholar on the topic of stress and addiction from a neurobiological perspective in humans. The most frequently cited articles and related references published in the last decade were finally redrafted into a narrative review based on 130 full-text articles.

RESULTS AND DISCUSSION

First, a brief overview of the neurobiology of stress and drug addiction is provided. Then, the role of stress in drug addiction is described. Stress is conceptualised as a major source of allostatic load, which result in progressive long-term changes in the brain, leading to a drug-prone state characterized by craving and increased risk of relapse. The effects of stress on drug addiction are mainly mediated by the action of corticotropin-releasing factor and other stress hormones, which weaken the hippocampus and prefrontal cortex and strengthen the amygdala, leading to a negative emotional state, craving and lack of executive control, increasing the risk of relapse. Both, drugs and stress result in an allostatic overload responsible for neuroadaptations involved in most of the key features of addiction: reward anticipation/craving, negative affect, and impaired executive functions, involved in three stages of addiction and relapse.

CONCLUSION

This review elucidates the crucial role of stress in drug addiction and highlights the need to incorporate the social context where brain-behaviour relationships unfold into the current model of addition.

Anti-stress neuropharmacological mechanisms and targets for addiction treatment: A translational framework

Stress-related substance use is a major challenge for treating substance use disorders. This selective review focuses on emerging pharmacotherapies with potential for reducing stress-potentiated seeking and consumption of nicotine, alcohol, marijuana, cocaine, and opioids (i.e., key phenotypes for the most commonly abused substances). I evaluate neuropharmacological mechanisms in experimental models of drug-maintenance and relapse, which translate more readily to individuals presenting for treatment (who have initiated and progressed). An affective/motivational systems model (three dimensions: valence, arousal, control) is mapped onto a systems biology of addiction approach for addressing this problem. Based on quality of evidence to date, promising first-tier neurochemical receptor targets include: noradrenergic (α1 and β antagonist, α2 agonist), kappa-opioid antagonist, nociceptin antagonist, orexin-1 antagonist, and endocannabinoid modulation (e.g., cannabidiol, FAAH inhibition); second-tier candidates may include corticotropin releasing factor-1 antagonists, serotonergic agents (e.g., 5-HT reuptake inhibitors, 5-HT3 antagonists), glutamatergic agents (e.g., mGluR2/3 agonist/positive allosteric modulator, mGluR5 antagonist/negative allosteric modulator), GABA-promoters (e.g., pregabalin, tiagabine), vasopressin 1b antagonist, NK-1 antagonist, and PPAR-γ agonist (e.g., pioglitazone). To address affective/motivational mechanisms of stress-related substance use, it may be advisable to combine agents with actions at complementary targets for greater efficacy but systematic studies are lacking except for interactions with the noradrenergic system. I note clinically-relevant factors that could mediate/moderate the efficacy of anti-stress therapeutics and identify research gaps that should be pursued. Finally, progress in developing anti-stress medications will depend on use of reliable CNS biomarkers to validate exposure-response relationships.

Interaction between noradrenergic and cholinergic signaling in amygdala regulates anxiety- and depression-related behaviors in mice

Medications that target the noradrenergic system are important therapeutics for depression and anxiety disorders. More recently, clinical studies have shown that the α2-noradrenergic receptor (α2AR) agonist guanfacine can decrease stress-induced smoking relapse during acute abstinence, suggesting that targeting the noradrenergic system may aid in smoking cessation through effects on stress pathways in the brain. Acetylcholine (ACh), like the nicotine in tobacco, acts at nicotinic acetylcholine receptors (nAChRs) to regulate behaviors related to anxiety and depression. We therefore investigated interactions between guanfacine and ACh signaling in tests of anxiolytic and antidepressant efficacy in female and male C57BL/6J mice, focusing on the amygdala as a potential site of noradrenergic/cholinergic interaction. The antidepressant-like effects of guanfacine were blocked by shRNA-mediated knockdown of α2AR in amygdala. Knockdown of the high-affinity β2 nAChR subunit in amygdala also prevented antidepressant-like effects of guanfacine, suggesting that these behavioral effects require ACh signaling through β2-containing nAChRs in this brain area. Ablation of NE terminals prevented the anxiolytic- and antidepressant-like effects of the nicotinic partial agonist cytisine, whereas administration of the cholinesterase antagonist physostigmine induced a depression-like phenotype that was not altered by knocking down α2AR in the amygdala. These studies suggest that ACh and NE have opposing actions on behaviors related to anxiety and depression and that cholinergic signaling through β2-containing nAChRs and noradrenergic signaling through α2a receptors in neurons of the amygdala are critical for regulation of these behaviors.

A preliminary investigation into the effects of doxazosin on cognitive functioning in tobacco-deprived and -satiated smokers

OBJECTIVE

To test the effects of doxazosin, an α1 antagonist, on cognitive functioning during tobacco withdrawal in smokers.

METHODS

Participants (n = 35) were randomly assigned to receive placebo, 4-mg/day, or 8-mg/day doxazosin. They completed a continuous performance task and self-reported their withdrawal symptoms at baseline and twice following a medication titration period: once in a tobacco-deprived state and again in a nondeprived state. Ability to resist smoking was assessed using a laboratory smoking-lapse paradigm.

RESULTS

Participants showed poorer cognitive performance on most measures taken from the continuous performance task when tobacco deprived. Eight-mg/day doxazosin improved inhibitory control during the nondeprivation session but did not affect sustained attention or reaction time. Participants receiving doxazosin reported fewer withdrawal symptoms during deprivation than those on placebo. Those showing the greatest improvement of inhibitory control under doxazosin were better able to resist smoking (i.e., latency to smoke) during a smoking lapse task. Self-reported withdrawal symptoms also were negatively associated with time to smoking.

CONCLUSIONS

Doxazosin reduced symptoms of tobacco withdrawal according to self-report and cognitive assessment and improved inhibitory control above predrug levels. This research identifies potential mechanisms by which doxazosin might improve smoking outcomes.

Role of Exogenous Progesterone in the Treatment of Men and Women with Substance Use Disorders: A Narrative Review

Substance use disorders (SUDs) remain problematic as many individuals are untreated or do not benefit from the currently available interventions. Thus, there is an urgent need to develop novel pharmacological interventions to treat SUDs. Evidence suggests that the female sex hormone, progesterone, attenuates the craving for and the euphoric effects of drugs of abuse. Research to date has demonstrated that progesterone may modulate responses to drugs of abuse and may have utility as a novel treatment for SUDs. A literature search was conducted to identify and examine studies that administered exogenous progesterone. Sixteen publications were identified, exploring the utility of exogenous progesterone or its metabolite, allopregnanolone, among a range of substances, including amphetamines (one study), benzodiazepines (one study), cocaine (nine studies), and tobacco/nicotine (five studies). Results indicated that exogenous progesterone and, its metabolite allopregnanolone, demonstrated preliminary efficacy as a treatment for substance use in both men and women. Notably, progesterone appears to target negative affect and augment cognitive functioning, especially among female substance users. Additional research is needed to explore the potential use of exogenous progesterone and allopregnanolone in the treatment of SUDs, including that associated with alcohol and opioids, but considering the current promising findings, exogenous progesterone and allopregnanolone may have utility as novel pharmacological treatments for SUDs.

Sex differences in the nicotinic acetylcholine and dopamine receptor systems underlying tobacco smoking addiction

Converging lines of evidence suggest that men generally smoke for nicotine-related reinforcement, whereas women smoke for non-nicotine factors. Women have more difficulty quitting smoking and are less responsive to nicotine replacement therapies than men, underscoring the importance of examining sex differences in the neurochemical mechanisms underlying nicotine-motivated behavior. We review the recent imaging literature on sex differences in the nicotinic acetylcholine receptor system and in the dopaminergic system in response to nicotine administration and tobacco smoking. We offer an explanation to unify imaging findings related to the dopamine system. We then propose a course of action for future medication development for tobacco smoking addiction.

Intersection of stress and gender in association with transitions in past year DSM-5 substance use disorder diagnoses in the United States

Background

Stress contributes to the development and maintenance of substance use disorders (SUD), with some research suggesting that the impact of stress on SUD is greater in women. However, this has yet to be evaluated in a national dataset, across major substances of abuse.

Methods

Using data from the newly available U.S. National Epidemiologic Survey on Alcohol and Related Conditions (NESARC; Wave 3; n=36,309) we evaluated relationships among past year stressful life events (0 or 1 vs. 2+ events, range 0-16) and gender, and their association with transitions (new vs. absent cases; ongoing vs. remitted cases) in Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) alcohol use disorder (AUD), tobacco use disorder (TUD), cannabis use disorder (CUD), and nonmedical prescription opioid use disorder (OUD) diagnoses.

Results

Having 2 or more stressful life events in the past year increased the odds of having a new AUD, TUD, CUD, and OUD (OR=3.14, 2.15, 5.52, and 3.06, respectively) or ongoing AUD, TUD, and CUD (OR=2.39, 2.62, and 2.95, respectively) compared to 0 or 1 stressful life event. A stress by gender interaction for new vs. absent AUD demonstrated that having 2 or more stressful life events was associated with increased odds of new AUD in men (OR=2.51) and even greater odds of new AUD in women (OR=3.94).

Conclusions

Results highlight that stress is a robust factor in both men and women with new or ongoing substance use disorders, and that effective treatments for substance use should consider the role of stress in addiction etiology and maintenance. There was little evidence for gender differences in the role of stress on transitions in substance use disorders, except for the onset of alcohol use disorders. Given that rates of alcohol use disorders are increasing in women; the impact of stress needs to be considered.

Pharmacotherapy for Co-Occurring Alcohol Use Disorder and Post-Traumatic Stress Disorder: Targeting the Opioidergic, Noradrenergic, Serotonergic, and GABAergic/Glutamatergic Systems

Alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD) are highly comorbid, and treatment outcomes are worse in individuals with both disorders. Several neurobiological systems have been implicated in the development and maintenance of AUD and PTSD, and pharmacologic interventions targeting these systems for singular diagnoses of AUD or PTSD have proven effective. However, there are no established treatments for co-occurring AUD and PTSD, and relatively few studies have examined potential pharmacotherapy for treating symptoms of both AUD and PTSD in comorbid populations. This review provides a brief overview of the studies to date on pharmacotherapeutic treatment interventions for comorbid AUD and PTSD and highlights future directions for promising targets that have potential in the treatment of individuals with this dual diagnosis. Clinical implications of these findings are also discussed. While current medications targeting the opioidergic, noradrenergic, serotonergic, and GABAergic/glutamatergic brain systems are only modestly efficacious in improving symptoms in individuals with comorbid AUD and PTSD, novel targets within these neurobiological systems may be clinically useful for treating alcohol use outcomes and PTSD symptom severity. More work is needed to optimize pharmacologic treatment strategies that target both alcohol-motivated behavior and PTSD-related symptoms in individuals with co-occurring AUD and PTSD.

One-Year Smoking Trajectories Among Established Adult Smokers With Low Baseline Motivation to Quit

INTRODUCTION

The majority of smokers do not intend to quit in the near term, making unmotivated smokers a key group to target in public health efforts. Although it is often assumed that continuing smokers will have stable rates of smoking over time, limited research has addressed this issue, particularly among smokers not seeking treatment. In the current study, the aims were to (1) characterize the trajectory of naturalistic smoking among unmotivated smokers and (2) examine relationships between naturalistic smoking trajectories and other smoking-related variables.

METHODS

The study sample comprised 579 control-group (ie, untreated) smokers within a parent clinical trial, who completed a total of nine assessments over 1 year.

RESULTS

Trajectory modeling identified four smoking trajectory groups: stable (72%), shallow decreasers (20%), steep decreasers (5%), and increasers (3%). Membership in the decreasing groups was associated with higher motivation to quit, greater history of quit attempts, and higher cigarettes per day. Females were more likely to be in the increasing versus stable group.

CONCLUSIONS

Findings provide needed information on stability and change in cigarette consumption over the course of 1 year among an untreated sample of smokers and identified baseline sociodemographic and smoking-related predictors of smoking trajectory group. Refining understanding of these groups is critical in updating population-based tobacco policy modeling efforts and informing cessation induction efforts that capitalize on naturalistic changes in smoking rate over time.

IMPLICATIONS

In the current study, we found that approximately 25% of smokers who endorsed low quit motivation at baseline reduced their cigarette consumption over the course of a year, while 3% increased their cigarette consumption and the majority of smokers (72%) maintained a stable pattern. Refining understanding of smoking trajectories is critical in updating population-based tobacco policy modeling efforts and informing cessation induction efforts that capitalize on naturalistic changes in smoking rate over time.

Probing for Neuroadaptations to Unpredictable Stressors in Addiction: Translational Methods and Emerging Evidence

Stressors clearly contribute to addiction etiology and relapse in humans, but our understanding of specific mechanisms remains limited. Rodent models of addiction offer the power, flexibility, and precision necessary to delineate the causal role and specific mechanisms through which stressors influence alcohol and other drug use. This review describes a program of research using startle potentiation to unpredictable stressors that is well positioned to translate between animal models and clinical research with humans on stress neuroadaptations in addiction. This research rests on a solid foundation provided by three separate pillars of evidence from (a) rodent behavioral neuroscience on stress neuroadaptations in addiction, (b) rodent affective neuroscience on startle potentiation, and (c) human addiction and affective science with startle potentiation. Rodent stress neuroadaptation models implicate adaptations in corticotropin-releasing factor and norepinephrine circuits within the central extended amygdala following chronic alcohol and other drug use that mediate anxious behaviors and stress-induced reinstatement among drug-dependent rodents. Basic affective neuroscience indicates that these same neural mechanisms are involved in startle potentiation to unpredictable stressors in particular (vs. predictable stressors). We believe that synthesis of these evidence bases should focus us on the role of unpredictable stressors in addiction etiology and relapse. Startle potentiation in unpredictable stressor tasks is proposed to provide an attractive and flexible test bed to encourage tight translation and reverse translation between animal models and human clinical research on stress neuroadaptations. Experimental therapeutics approaches focused on unpredictable stressors hold high promise to identify, repurpose, or refine pharmacological and psychosocial interventions for addiction.

Brain circuitry associated with the development of substance use in bipolar disorder and preliminary evidence for sexual dimorphism in adolescents

Substance use disorders and mood disorders are highly comorbid and confer a high risk for adverse outcomes. However, data are limited on the neurodevelopmental basis of this comorbidity. Substance use initiation typically occurs during adolescence, and sex-specific developmental mechanisms are implicated. In this preliminary study, we review the literature and investigate regional gray matter volume (GMV) associated with subsequent substance use problems in adolescents with bipolar disorder (BD) and explore these associations for females and males. Thirty adolescents with DSM-IV-diagnosed BD and minimal alcohol/substance exposure completed baseline structural magnetic resonance imaging scans. At follow-up (on average 6 years post baseline), subjects were administered the CRAFFT interview and categorized into those scoring at high ( ≥ 2: CRAFFT_HIGH ) vs. low ( < 2: CRAFFT_LOW ) risk for alcohol/substance problems. Lower GMV in prefrontal, insular, and temporopolar cortices were observed at baseline among adolescents with BD reporting subsequent alcohol and cannabis use compared to adolescents with BD who did not (P < 0.005, clusters ≥ 20 voxels). Lower dorsolateral prefrontal GMV was associated with future substance use in both females and males. In females, lower orbitofrontal and insula GMV was associated with future substance use, while in males, lower rostral prefrontal GMV was associated with future use. Lower orbitofrontal, insular, and temporopolar GMV was observed in those who transitioned to smoking tobacco. Findings indicate that GMV development is associated with risk for future substance use problems in adolescents with BD, with results implicating GMV development in regions subserving emotional regulation in females and regions subserving executive processes and attention in males. © 2016 Wiley Periodicals, Inc.

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

Introduction

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

Methods

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

Results

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

Conclusions

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

Implications

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

Sex as a biological variable: Drug use and abuse

The study of sex as a biological variable is a necessary emphasis across a wide array of endpoints, including basic neuroscience, medicine, mental health, physiology and behavior. The present review summarizes work from clinical and preclinical populations on sex differences in drug use and abuse, ranging from initiation to escalation/dysregulation and from drug cessation/abstinence to relapse. These differences are analyzed in the context of the addiction cycle conceptualization of Koob and his colleagues and address patterns of drug use (binge/intoxication), motivation underlying its use (withdrawal/negative affect) and likelihood and causes of craving and relapse of drug taking (preoccupation/anticipation). Following this overview, an assessment of the basis for the reported sex differences is discussed in the context of the affective (rewarding and aversive) properties of drugs of abuse and how such properties and their balance vary with sex and contribute to drug intake. Finally, the interaction of sex with several experiential (drug history) and subject (age) factors and how these interactions affect reward and aversion are discussed to highlight the importance of understanding such interactions in predicting drug use and abuse. We note that sex as a biological variable remains one of critical evaluation and that such investigations of sex differences in drug use and abuse continue and be expanded to assess all facets of their mediation, including these affective properties, how their balance may be impacted by the multiple conditions under which drugs are taken and how this overall balance affects drug use and addiction vulnerability.

Atomoxetine in abstinent cocaine users: Sex differences

Data presented are from a sex-differences secondary analysis of a human laboratory investigation of single doses of atomoxetine (40 mg and 80 mg) versus placebo in abstinent individuals with cocaine use disorders (CUD). Subjective drug effects, cognitive performance and cardiovascular measures were assessed. The primary atomoxetine dose analyses (which do not consider sex as a factor) are reported in full elsewhere (DeVito et al., 2017) [1].

Effect of doxazosin on stress reactivity and the ability to resist smoking

Preclinical findings support a role for α1-adrenergic antagonists in reducing nicotine-motivated behaviors, but these findings have yet to be translated to humans. The current study evaluated whether doxazosin would attenuate stress-precipitated smoking in the human laboratory. Using a well-validated laboratory analogue of smoking-lapse behavior, this pilot study evaluated whether doxazosin (4 and 8 mg/day) versus placebo attenuated the effect of stress (vs neutral imagery) on tobacco craving, the ability to resist smoking and subsequent ad-libitum smoking in nicotine-deprived smokers ( n=35). Cortisol, adrenocorticotropin, norepinephrine, epinephrine, and physiologic reactivity were assessed. Doxazosin (4 and 8 mg/day vs placebo) decreased cigarettes per day during the 21-day titration period. Following titration, doxazosin (4 and 8 mg/day vs placebo) decreased tobacco craving. During the laboratory session, doxazosin (8 mg/day vs placebo) further decreased tobacco craving following stress versus neutral imagery. Doxazosin increased the latency to start smoking following stress, and reduced the number of cigarettes smoked. Dosage of 8 mg/day doxazosin increased or normalized cortisol levels following stress imagery and decreased cortisol levels following neutral imagery. These preliminary findings support a role for the noradrenergic system in stress-precipitated smoking behavior, and support further development of doxazosin as a novel pharmacotherapeutic treatment strategy for smoking cessation.

Targeting the Brain Stress Systems for the Treatment of Tobacco/Nicotine Dependence: Translating Preclinical and Clinical Findings

Tobacco use is the leading cause of preventable mortality in the United States, and Food and Drug Administration (FDA) approved medications fail to maintain long-term abstinence for the majority of smokers. One of the principal mechanisms associated with the initiation, maintenance of, and relapse to smoking is stress. Targeting the brain stress systems as a potential treatment strategy for tobacco dependence may be of therapeutic benefit. This review explores brain stress systems in tobacco use and dependence. The corticotropin-releasing factor (CRF) system, the hypothalamic-pituitary-adrenal (HPA) axis, and the noradrenergic system are discussed in relation to tobacco use. Preclinical and clinical investigations targeting these stress systems as treatment strategies for stress-induced tobacco use are also discussed. Overall, nicotine-induced activation of the CRF system, and subsequent activation of the HPA axis and noradrenergic system may be related to stress-induced nicotine-motivated behaviors. Pharmacological agents that decrease stress-induced hyperactivation of these brain stress systems may improve smoking-related outcomes.

Antidepressant-like effects of guanfacine and sex-specific differences in effects on c-fos immunoreactivity and paired-pulse ratio in male and female mice

RATIONALE

The a2A-noradrenergic agonist guanfacine can decreases stress-induced smoking in female, but not male, human smokers. It is not known whether these effects are due to effects on mood regulation and/or result from nicotinic-cholinergic interactions.

OBJECTIVES

The objective of the study was to determine whether there are sex differences in the effect of guanfacine in tests of anxiolytic and antidepressant efficacy in mice at baseline and in a hypercholinergic model of depression induced by the acetylcholinesterase inhibitor physostigmine.

METHODS

The effects of guanfacine were measured in the light/dark box, tail suspension, and the forced swim test in female and male C57BL/6J mice. In parallel, electrophysiological properties were evaluated in the prefrontal cortex, a critical brain region involved in stress responses. c-fos immunoreactivity was measured in other brain regions known to regulate mood.

RESULTS

Despite a baseline sex difference in behavior in the forced swim test (female mice were more immobile), guanfacine had similar, dose-dependent, antidepressant-like effects in mice of both sexes (optimal dose, 0.15 mg/kg). An antidepressant-like effect of guanfacine was also observed following pre-treatment with physostigmine. A sex difference in the paired-pulse ratio in the prefrontal cortex (PFC) (male, 1.4; female, 2.1) was observed at baseline that was normalized by guanfacine. Other brain areas involved in cholinergic control of depression-like behaviors, including the basolateral amygdala and lateral septum, showed sex-specific changes in c-fos expression.

CONCLUSIONS

Guanfacine has a robust antidepressant-like effect and can reverse a depression-like state induced by increased acetylcholine (ACh) signaling. These data suggest that different brain areas are recruited in female and male mice, despite similar behavioral responses to guanfacine.