Hypothalamic–Pituitary–Adrenocortical responses to psychological stress and risk for smoking relapse

Patterns of adaptation to stress cardiovascular responses in smokers during ad libitum smoking and withdrawal

There is considerable evidence documenting associations between tobacco smoking, including initiation, maintenance, and relapse of addiction, with diminished cardiovascular responses to acute psychological stress. However, less is known about how smokers respond to repeated stress across time. The current study examined patterns of cardiovascular reactivity and adaptation to recurrent stress among 24-h abstinence smokers, smokers who continued to smoke at their normal rate, and non-smokers. Smokers were randomly assigned to one of two groups; ad libitum (n = 42), or 24 h abstinence (n = 61); non-smokers (n = 43) provided comparative referencing. Across the two laboratory sessions, participants (n = 149) were asked to complete a modified version of the trier social stress test, while monitoring systolic and diastolic blood pressure, and heart rate activity. Results showed that while non-smokers had elevated cardiovascular reactivity to begin with, they showed a greater capacity to habituate to recurrent stress across sessions. The data also suggest that smokers displayed lower cardiovascular reactivity to acute psychological stress and showed little habituation to repeated stress. In adjusted models, smokers exhibited less systolic blood pressure habituation to stress. This response profile in smokers may be a potential mechanism that leads to further cardiotoxic effects on health.

Nicotine addiction and the influence of life adversity and acute stress on PYY: Prediction of early smoking relapse

Early life adversity (ELA) is associated with earlier initiation and maintenance of tobacco smoking and with a greater risk of subsequent relapse. There is growing evidence that appetite hormones, including peptide YY (PYY), which modulates craving and satiety responses, play a role in stress and addiction processes. This study employed a quasi-experimental design to examine the association between ELA and circulating PYY stress responses in smokers and nonsmokers (N = 152, ages 19-73 years) to examine the effects of nicotine addiction. Smokers initiated a quit attempt as part of the study and were classified as either abstinent smokers or relapsed smokers based on their nicotine use during the follow-up period. PYY levels were measured at five timepoints during three lab sessions and compared between nonsmokers and the two smoking groups (abstainers, relapsers): while smokers were using nicotine ad libitum, 24 h after smokers initiated a quit attempt, and 4 weeks after smokers initiated a quit attempt. Multivariate analyses showed the main effects of time on PYY, which decreased over time within each session. The main effects of ELA during the first (ad libitum smoking) and second (24-h post-cessation for smokers) sessions indicated that experiencing ELA was associated with lower PYY. No systematic effect of nicotine addiction or relapse was observed in this study. These findings suggest that adults with higher ELA may experience lower PYY. Additional research is needed to further explore the role of PYY in stress and addiction processes.

Hemodynamic Reactivity to Mental Stress and Cognitive Function in Coronary Artery Disease

OBJECTIVE

People with coronary artery disease (CAD) are at higher risk of cognitive impairment than those without CAD. Psychological stress is a risk factor for both conditions, and assessing the hemodynamic reactivity to mental stress could explain the link between stress and cognitive function.

METHODS

A total of 779 individuals with stable CAD from two prospective cohort studies were included. All individuals underwent acute mental stress testing, as well as conventional stress testing. Cognitive function was assessed both at baseline and at a 2-year follow-up. The rate-pressure product (RPP) was calculated as the mean systolic blood pressure times the mean heart rate at rest. RPP reactivity was defined as the maximum RPP during standardized mental stress test minus the RPP at rest.

RESULTS

After multivariable adjustment, every standard deviation decrease in RPP reactivity with mental stress was associated with slower completion of Trail-A and Trail-B in both cohorts (13% and 11% in cohort 1, and 15% and 16% in cohort 2, respectively; p for all <.01). After a 2-year follow-up period, every standard deviation decrease in RPP reactivity with mental stress was associated with a 8% and 9% slower completion of Trail-A and Trail-B, respectively ( p for all <.01). There was no significant association between RPP reactivity with conventional stress testing and any of the cognitive tests.

CONCLUSION

In the CAD population, a blunted hemodynamic response to mental stress is associated with slower visuomotor processing and worse executive function at baseline and with greater decline in these abilities over time.

Social network size moderates the association between loneliness and cardiovascular reactivity to acute stress

Loneliness and objective measures of social isolation (e.g., social network size) have been associated with increased risk of cardiovascular disease (CVD). However, the evidence is mixed and the precise causal mechanisms remain unclear. Cardiovascular reactivity (CVR) to acute stress has been posited as a proposed mechanism. This study aimed to investigate: (i) effects of loneliness and social isolation on CVR to stress and, (ii) whether the loneliness - CVR relationship was moderated by social network size. Two hundred and six participants from the Pittsburgh Cold Study underwent a modified version of the Trier Social Stress Task. Cardiovascular measures of systolic (SBP) and diastolic blood pressure (DBP) and heart rate (HR) were taken throughout the laboratory stress trial. Hierarchical regression analyses found that social network size was positively associated with DBP reactivity (β = 0.19 95 % CI [0.05, 0.29] p = 0.005), while loneliness was not. In addition, social network size moderated the loneliness - DBP reactivity relationship such that a higher number of outer social network ties were beneficial at lower levels of loneliness but not higher. The current study contributes new evidence linking loneliness and social network size to cardiovascular psychophysiology but raises questions about the loneliness - CVD relationship. The findings confirm the importance of social network size and highlight that the characteristics of the networks may be more important than the number of networks.

Deficient sleep, altered hypothalamic functional connectivity, depression and anxiety in cigarette smokers

Background

Deficient sleep is implicated in nicotine dependence as well as depressive and anxiety disorders. The hypothalamus regulates the sleep-wake cycle and supports motivated behavior, and hypothalamic dysfunction may underpin comorbid nicotine dependence, depression and anxiety. We aimed to investigate whether and how the resting state functional connectivities (rsFCs) of the hypothalamus relate to cigarette smoking, deficient sleep, depression and anxiety.

Methods

We used the data of 64 smokers and 198 age- and sex-matched adults who never smoked, curated from the Human Connectome Project. Deficient sleep and psychiatric problems were each assessed with Pittsburgh Sleep Quality Index (PSQI) and Achenbach Adult Self-Report. We processed the imaging data with published routines and evaluated the results at a corrected threshold, all with age, sex, and the severity of alcohol use as covariates.

Results

Smokers vs. never smokers showed poorer sleep quality and greater severity of depression and anxiety. In smokers only, the total PSQI score, indicating more sleep deficits, was positively associated with hypothalamic rsFCs with the right inferior frontal/insula/superior temporal and postcentral (rPoCG) gyri. Stronger hypothalamus-rPoCG rsFCs were also associated with greater severity of depression and anxiety in smokers but not never smokers. Additionally, in smokers, the PSQI score completely mediated the relationships of hypothalamus-rPoCG rsFCs with depression and anxiety severity.

Conclusions

These findings associate hypothalamic circuit dysfunction to sleep deficiency and severity of depression and anxiety symptoms in adults who smoke. Future studies may investigate the roles of the hypothalamic circuit in motivated behaviors to better characterize the inter-related neural markers of smoking, deficient sleep, depression and anxiety.

Neurobiology of Stress-Induced Nicotine Relapse

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

Association between job satisfaction and current smoking and change in smoking behavior: a 16-year longitudinal study in South Korea

BACKGROUND AND AIMS

Previous studies have found that job satisfaction is closely associated with various health outcomes of workers. Our study measured the association between job satisfaction and current smoking and change in smoking behavior.

DESIGN

Data from the longitudinal Korea Labor and Income Panel Study (KLIPS) that consist of nationally representative samples were used. The repeated measures analysis was conducted.

SETTING

South Korea, 2005-2021.

PARTICIPANTS

In total, 21 154 workers in Korea followed from 2005 to 2021 (145 120 observations) were included as study participants.

MEASUREMENTS

The main predictor variable, job satisfaction, was assessed using a five-item general job satisfaction questionnaire. Job satisfaction was classified into 'dissatisfied', 'neutral' and 'satisfied', according to the tertiles of the sum of scores. The outcomes of interest were current smoking and initiation and cessation of smoking in the subsequent year.

FINDINGS

Compared with those with a neutral level of job satisfaction, those who reported dissatisfaction with their job had an increased risk of smoking initiation [odds ratio (OR) = 1.11, 95% confidence interval (CI) = 1.01-1.22)]. Workers satisfied with their jobs were associated with a decreased likelihood of current smoking (OR = 0.96, 95% CI = 0.94-0.98) and smoking initiation (OR = 0.90, 95% CI = 0.81-0.99). There was a positive relationship between cumulative years of job dissatisfaction and smoking risk: > 4 years of experiencing job dissatisfaction was positively related to current smoking (OR = 1.14, 95% CI = 1.06-1.24) and smoking initiation (OR = 1.22, 95% CI = 1.00-1.49) and negatively related to smoking cessation (OR = 0.84, 95% CI = 0.72-0.99).

CONCLUSIONS

In Korea, job dissatisfaction appears to be associated with an increased risk of smoking initiation.

Hemodynamic Reactivity to Mental Stress in Patients With Coronary Artery Disease

Importance

The clinical significance of hemodynamic reactivity to mental stress in the population with coronary artery disease (CAD) is unclear.

Objective

To investigate the association between hemodynamic reactivity to mental stress and the risk of adverse cardiovascular events in patients with stable CAD.

Design, Setting, and Participants

This cohort study included individuals with stable CAD from 2 prospective studies from a university-based hospital network: the Mental Stress Ischemia Prognosis Study (MIPS) and the Myocardial Infarction and Mental Stress Study 2 (MIMS2). Participants were enrolled between June 2011 and March 2016 and followed up for a median of 6.0 (IQR, 5.6-6.0) years in MIPS and 4.6 (IQR, 3.8-5.3) years in MIMS2. Data were analyzed from December 1, 2022, to February 15, 2023.

Exposures

The rate-pressure product (RPP) was calculated as the mean systolic blood pressure times the mean heart rate at rest. Rate-pressure product reactivity was calculated as the maximum RPP during a standardized mental stress test minus the RPP at rest.

Main Outcomes and Measures

The primary outcome was a composite of cardiovascular death or nonfatal myocardial infarction. The secondary end point additionally included hospitalizations for heart failure.

Results

From the total of 938 individuals from the pooled cohort (mean [SD] age, 60.2 [10.1] years; 611 [65.1%] men), 631 participated in MIPS and 307 in MIMS2. A total of 373 individuals (39.8%) were Black, 519 (55.3%) were White, and 46 (4.9%) were of unknown race or ethnicity. The RPP increased by a mean (SD) of 77.1% (23.1%) during mental stress (mean [SD] absolute change, 5651 [2878]). For every SD decrease in RPP reactivity with mental stress, the adjusted hazard ratios for the primary and secondary end points were 1.30 (95% CI, 1.04-1.72) and 1.30 (95% CI, 1.06-1.56), respectively, in MIPS and 1.41 (95% CI, 1.06-1.97) and 1.21 (95% CI, 1.02-1.60), respectively, in MIMS2. In the pooled sample, when RPP reactivity to mental stress was added to a model including traditional clinical risk characteristics, model discrimination for adverse events improved (increase in C statistic of 5% for the primary end point; P = .009).

Conclusions and Relevance

In this cohort study of individuals with stable CAD, a blunted cardiovascular reactivity to mental stress was associated with adverse outcomes. Future studies are needed to assess the clinical utility of mental stress reactivity testing in this population.

Sex difference in the associations among risk factors with depression in a large Taiwanese population study

Background

Depression is a common psychiatric health issue affecting an estimated 5% of adults worldwide, and it can lead to disability and increased economic burden. Consequently, identifying the factors associated with depression as early as possible is a vital issue. The aim of this study was to explore these associations in a large cohort of 121,601 Taiwanese participants in the Taiwan Biobank, and also to identify sex differences in the associations.

Methods

The study cohort included 77,902 women and 43,699 men (mean age, 49.9 ± 11.0 years), who were further classified into those with depression (n = 4,362; 3.6%) and those without depression (n = 117,239; 96.4%).

Results

The results of multivariable analysis showed that female sex (vs. male sex; odds ratio = 2.578; 95% confidence interval = 2.319–2.866; p &lt; 0.001) was significantly associated with depression. Older age, diabetes mellitus (DM), hypertension, low systolic blood pressure (SBP), smoking history, living alone, low glycated hemoglobin (HbA1c), high triglycerides, and low uric acid were significantly associated with depression in the men. In the women, older age, DM, hypertension, low SBP, smoking history, alcohol history, education level of middle and high school (vs. lower than elementary school), living alone, high body mass index (BMI), menopause, low HbA1c, high triglycerides, high total cholesterol, low estimated glomerular filtration rate (eGFR), and low uric acid were significantly associated with depression. Further, there were significant interactions between sex and DM (p = 0.047), smoking history (p &lt; 0.001), alcohol use (p &lt; 0.001), BMI (p = 0.022), triglyceride (p = 0.033), eGFR (p = 0.001), and uric acid (p = 0.004) on depression.

Conclusion

In conclusion, our results showed sex differences in depression, and the women were significantly associated with depression compared to men. Furthermore, we also found sex differences among the risk factors associated with depression.

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

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

Acculturation Style Is Associated with Stress and Tobacco Use among East African Immigrants

While tobacco use rates are relatively high among East African immigrants in the U.S., factors contributing to this high rate are largely unknown. Acculturation is associated with stress and substance use. Whether acculturation styles are related to stress and current tobacco use has not been tested among this population. We conducted a cross-sectional study that included 376 East African adults who provided information on demographic background, acculturation style, acculturative stress, depressive symptoms, and tobacco use. Multivariate analysis indicated that individuals who were distant to both the culture of the host country and the culture of origin (marginalization style) had greater levels of acculturative stress than those who adopted both cultures (integration style; p < .001). Marginalized people were four to eight times and assimilated people were three to four times more likely than integration people to be a current tobacco user (p < .04). This relationship did not change after controlling for demographic information and stress. In this study, acculturation style was associated with perceived stress and current tobacco use among East African immigrants. Research focused on characterizing integrated individuals may guide efforts to develop culturally-relevant strategies to reduce tobacco-related disparities among East African individuals.

Blunted cortisol and normal sympathetic nervous system responses to an acute psychosocial stressor in internet addiction

Studies have demonstrated that addiction leads to blunted responses of cortisol and sympathetic nervous system (SNS) to acute stressors; however, limited studies have examined the neuroendocrine and SNS stress responses in Internet addiction (IA). To examine acute stress responses in IA, the current study recruited a total of 76 Japanese university students and staff members (51 females and 25 males, mean age = 22.4 years, SD = 4.7), and measured the salivary cortisol, salivary alpha-amylase (sAA), and blood pressure (BP) responses to an acute stressor under stress or a nonstress placebo conditions in IA and non-IA groups. The results revealed that patients with IA showed a blunted cortisol response to a stressor. In contrast, no differences were found in the sAA and BP responses between the IA and non-IA groups. These results suggest that IA may be characterized by blunted cortisol responses in acute stress settings.

The relationship between sex, personality traits, and the hypothalamic-pituitary-adrenocortical axis

The aim of our study was to examine whether there are sex-based differences in the relationship between personality traits and hypothalamic-pituitary-adrenal (HPA) axis measures. A total of 106 healthy volunteers (56.6% women; age: 48.0 ± 15.8 years) were studied. The revised temperament and character inventory (TCI-R) and the Childhood Trauma Questionnaire (CTQ) were administered. HPA axis function was assessed using three dynamic measures: the cortisol awakening response (CAR), the diurnal cortisol slope, and the cortisol suppression ratio with 0.25 mg of dexamethasone (DSTR). Female sex was associated with an increased CAR and a more flattened diurnal cortisol slope, although a negative significant interaction between harm avoidance and female sex was found. Regarding the DSTR, perseverance was associated with increased cortisol suppression after dexamethasone; sex did not affect this association. Our study suggests that the relationship between specific personality traits (harm avoidance) and HPA axis measures (CAR, diurnal slope) differs according to sex.

The Impact of Smoking on the Development and Severity of Chronic Pain

PURPOSE OF REVIEW

The purpose of this review is to examine the impact of smoking and its role on the development of chronic pain and provide a critical review of recent literature.

RECENT FINDINGS

Recent studies demonstrate the bidirectional and dependent relationship between smoking and chronic pain. Those who are in pain have a more difficult time in the cessation of smoking as well as an increased sensitivity to pain during abstinence, lower confidence, and higher relapse rates. The fear of pain and the anxiety and depression that abstinence causes results in a grim outcome for long-term cessation. The dependent nature between chronic pain and smoking is affected by numerous variables. Providers should consider a multiprong approach to treating chronic pain and targeting smoking cessation treatment by providing motivational therapy, nicotine replacement, and medication therapies to prevent relapse, and providing those who are more likely to relapse with a higher level of care.

Effects of regular cannabis and nicotine use on acute stress responses: chronic nicotine, but not cannabis use, is associated with blunted adrenocortical and cardiovascular responses to stress

RATIONALE

Cannabis is one of the most prevalent substances used by tobacco smokers and, in light of the growing list of states and territories legalizing cannabis, it is expected that co-use of cannabis and nicotine will escalate significantly and will lead to continuing challenges with tobacco use.

OBJECTIVES

This study was conducted to examine the interactive effects of chronic cannabis and nicotine use on adrenocortical, cardiovascular, and psychological responses to stress and to explore sex differences in these effects.

METHODS

Participants (N = 231) included cannabis-only users, nicotine-only users, co-users of both substances, and a non/light-user comparison group. After attending a medical screening session, participants completed a laboratory stress session during which they completed measures of subjective states, cardiovascular responses, and salivary cortisol during baseline (rest) and after exposure to acute stress challenges.

RESULTS

Nicotine use, but not cannabis use, was associated with blunted cortisol and cardiovascular responses to stress across both men and women. Men exhibited larger cortisol responses to stress than women. Co-users had significantly larger stress-related increases in cannabis craving than cannabis-only users. Cannabis users reported smaller increases in anxiety during stress than cannabis non/light-users, and both male nicotine-only users and male cannabis-only users experienced significantly smaller increases in stress than their non/light-user control counterparts.

CONCLUSIONS

This study replicates and extends earlier research on the impacts of sex and nicotine use on stress responses, and it provides novel findings suggesting that when co-used with nicotine, cannabis use may not confer additional alterations to physiological nor subjective responses to stress. Co-use, however, was associated with enhanced stress-related craving for cannabis.

Developmental nicotine exposure and masculinization of the rat preoptic area

Nicotine is a neuroteratogenic component of tobacco smoke, e-cigarettes, and other products and can exert sex-specific effects in the developing brain, likely mediated through sex hormones. Estradiol modulates expression of nicotinic acetylcholine receptors in rats, and plays critical roles in neurodevelopmental processes, including sexual differentiation of the brain. Here, we examined the effects of developmental nicotine exposure on the sexual differentiation of the preoptic area (POA), a brain region that normally displays robust structural sexual dimorphisms and controls adult mating behavior in rodents. Using a rat model of gestational exposure, developing pups were exposed to nicotine (2 mg/kg/day) via maternal osmotic minipump (subcutaneously, sc) throughout the critical window for brain sexual differentiation. At postnatal day (PND) 4, a subset of offspring was analyzed for epigenetic effects in the POA. At PND40, all offspring were gonadectomized, implanted with a testosterone-releasing capsule (sc), and assessed for male sexual behavior at PND60. Following sexual behavior assessment, the area of the sexually dimorphic nucleus of the POA (SDN-POA) was measured using immunofluorescent staining techniques. In adults, normal sex differences in male sexual behavior and in the SDN-POA area were eliminated in nicotine-treated animals. Using novel analytical approaches to evaluate overall masculinization of the adult POA, we identified significant masculinization of the nicotine-treated female POA. In neonates (PND4), nicotine exposure induced trending alterations in methylation-dependent masculinizing gene expression and DNA methylation levels at sexually-dimorphic differentially methylated regions, suggesting that developmental nicotine exposure is capable of triggering masculinization of the rat POA via epigenetic mechanisms.

Age- and Sex-Dependent Nicotine Pretreatment Effects on the Enhancement of Methamphetamine Self-Administration in Sprague-Dawley Rats

INTRODUCTION

Initiation of tobacco products typically occurs in adolescence. Adolescence is a critical period in development where the maturation of brain neurocircuitry is vulnerable to nicotine. Nicotine-containing products and psychostimulants, such as methamphetamine (METH), are often co-abused. Rodent studies have shown that nicotine exposure in early adolescence increases subsequent drug intake and reward. Given the exponential increase in e-cigarette use among adolescents, there is a pressing need to understand whether adolescent nicotine exposure impacts concurrent increased methamphetamine use. The objective of this study is to evaluate age, sex, and longitudinal effects of nicotine pretreatment on methamphetamine reinforcement.

METHODS

Male and female Sprague-Dawley rats were pretreated with a sub-chronic, low dose nicotine (2x, 30 μg/kg/0.1 mL, intravenous) or saline during early adolescence (postnatal days 28-31) or adulthood (postnatal days 86-89). Following nicotine pretreatment, on postnatal day 32 or postnatal day 90, animals underwent operant intravenous self-administration for methamphetamine (20 μg/kg/inf) over a 2-hour period for five consecutive days.

RESULTS

Early adolescent nicotine exposure enhances intravenous methamphetamine self-administration in male, but not female adolescents. Male adult rats self-administer methamphetamine over the 5-day testing period, independent of nicotine exposure. In contrast, nicotine exposure increases methamphetamine self-administration in female adults during the later sessions of the 5-day testing period.

CONCLUSIONS

Taken together, our data highlight age- and sex-dependent effects of low dose, sub-chronic nicotine pretreatment on subsequent intravenous methamphetamine self-administration.

IMPLICATIONS

A majority of polysubstance users begin smoking before the age of 18. Mounting evidence highlights adolescent susceptibility to nicotine exposure on brain and behavior. With the escalation in nicotine-containing products and stimulant use among adolescents, it is important to identify the consequences from adolescent nicotine use, including polysubstance use. Our study provides evidence that adolescent nicotine exposure enhances subsequent methamphetamine use, with important sex- and age-dependent effects.

Cardiovascular Stress Reactivity and Health: Recent Questions and Future Directions

OBJECTIVE

High cardiovascular reactions to psychological stress are associated with the development of hypertension, systemic atherosclerosis, and cardiovascular disease. However, it has become apparent that low biological stress reactivity also may have serious consequences for health, although less is known about the mechanisms of this. The objectives of this narrative review and opinion article are to summarize and consider where we are now in terms of the usefulness of the reactivity hypothesis and reactivity research, given that both ends of the reactivity spectrum seem to be associated with poor health, and to address some of the key criticisms and future challenges for the research area.

METHODS

This review is authored by the members of a panel discussion held at the American Psychosomatic Society meeting in 2019, which included questions such as the following: How do we measure high and low reactivity? Can high reactivity ever indicate better health? Does low or blunted reactivity simply reflect less effort on task challenges? Where does low reactivity originate from, and what is a low reactor?

RESULTS

Cardiovascular (and cortisol) stress reactivity are used as a model to demonstrate an increased understanding of the different individual pathways from stress responses to health/disease and show the challenges of how to understand and best use the reconstruction of the long-standing reactivity hypothesis given recent data.

CONCLUSIONS

This discussion elucidates the gaps in knowledge and key research issues that still remain to be addressed in this field, and that systematic reviews and meta-analyses continue to be required.

Blunted opioid regulation of the HPA stress response during nicotine withdrawal: therapeutic implications

Endogenous opioids regulate pain, drug reward, and stress responses. We have previously shown reduced hypothalamic-pituitary-adrenal (HPA) responses to psychological stress and to opioid blockade among dependent smokers. In this study, we examined the extent to which biologically confirmed nicotine withdrawal alters endogenous opioid regulation of HPA axis functioning during rest and in response to acute stress. Smokers were randomly assigned to one of two conditions; 24 h withdrawal from all nicotine-containing products (n = 62) or smoking ad libitum (n = 44). A nonsmoking comparison group (n = 43) was also included. Participants (85 males and 64 females) completed two acute stress sessions during which a placebo or 50 mg of naltrexone (opioid antagonist) were administered using a double-blind design. Blood and saliva samples (assayed for cortisol and adrenocorticotropic hormone, i.e. ACTH) and mood measures were obtained during a resting absorption period, after acute stress (public speaking, mental arithmetic, and cold pressor tasks), and during an extended recovery period. Results indicated that opioid blockade (naltrexone) was associated with increased ACTH and cortisol responses to stress, and tobacco withdrawal was associated with blunted hormonal responses. A pattern of sex differences also emerged, with women exhibiting reduced ACTH responses to stress and higher ACTH and plasma cortisol responses to opioid blockade. These results indicated that compared to ad libitum smoking, nicotine withdrawal is associated with blunted opioid modulation of the HPA axis. Sex may modulate these effects. Blunted endogenous opioid regulation may underlie an incentive process that reinforces smoking behavior and may warrant therapeutic attention.

The therapeutic potential of GLP-1 analogues for stress-related eating and role of GLP-1 in stress, emotion and mood: a review

Stress and low mood are powerful triggers for compulsive overeating, a maladaptive form of eating leading to negative physical and mental health consequences. Stress-vulnerable individuals, such as people with obesity, are particularly prone to overconsumption of high energy foods and may use it as a coping mechanism for general life stressors. Recent advances in the treatment of obesity and related co-morbidities have focused on the therapeutic potential of anorexigenic gut hormones, such as glucagon-like peptide 1 (GLP-1), which acts both peripherally and centrally to reduce energy intake. Besides its appetite suppressing effect, GLP-1 acts on areas of the brain involved in stress response and emotion regulation. However, the role of GLP-1 in emotion and stress regulation, and whether it is a viable treatment for stress-induced compulsive overeating, has yet to be established. A thorough review of the pre-clinical literature measuring markers of stress, anxiety and mood after GLP-1 exposure points to potential divergent effects based on temporality. Specifically, acute GLP-1 injection consistently stimulates the physiological stress response in rodents whereas long-term exposure indicates anxiolytic and anti-depressive benefits. However, the limited clinical evidence is not as clear cut. While prolonged GLP-1 analogue treatment in people with type 2 diabetes improved measures of mood and general psychological wellbeing, the mechanisms underlying this may be confounded by associated weight loss and improved blood glucose control. There is a paucity of longitudinal clinical literature on mechanistic pathways by which stress influences eating behavior and how centrally-acting gut hormones such as GLP-1, can modify these. (250).

Early life adversity and appetite hormones: The effects of smoking status, nicotine withdrawal, and relapse on ghrelin and peptide YY during smoking cessation

There is evidence suggesting that ghrelin and peptide YY (PYY) modulate stress responses and the rewarding effects of drugs, although no research has examined the impact of exposure to early life stress on these hormones in smokers nor during smoking cessation. This study examined the relationships between early life adversity (ELA) and circulating ghrelin and PYY during ad libitum smoking and early withdrawal in tobacco smokers (N = 98) who were interested in cessation. We also included a comparison group of nonsmokers (N = 36). We prospectively compared levels of hormones between smokers who were successful in quitting within a 2-week period, smokers who relapsed during that period, and nonsmokers. Results showed that ELA was positively associated with elevated ghrelin in nonsmokers. Among those reporting no ELA, successful quitters had higher ghrelin levels than nonsmokers during ad libitum smoking, while relapsers had higher ghrelin levels than nonsmokers during withdrawal. In addition, having no ELA was associated with a decline in ghrelin from the ad libitum to abstinence sessions in successful quitters; this withdrawal-related decline was not found in relapsers. Although effects of ELA, smoking group, and time on PYY were not significant, greater PYY was associated with reduced urges to smoke during withdrawal. These findings suggest the importance of considering changes in appetite-related hormones in individuals who are dependent on tobacco. This research provides additional indications for effects of ELA on appetite-stimulating hormones.

Influences of Fasting on Stress Response and Withdrawal Symptoms in Habitual Khat Users

BACKGROUND

Fasting changes mood and physiological states. Substance use, such as khat use, is prohibited during fasting during Ramadan, a traditional practice among Muslims. Habitual khat use is associated with increased negative affect and altered psychobiological stress responses. Effects of fasting on stress responses, mood, and withdrawal symptoms among khat users have not been examined.

METHODS

In this study, 80 individuals completed an ambulatory monitoring period and a laboratory assessment session. Participants who completed the study while fasting during Ramadan were matched by gender and khat use status with participants who completed the study while not fasting. This resulted in 40 participants (12 females and 28 males; 25 khat users and 15 nonusers) in each fasting group. Cardiovascular (blood pressure and heart rate) and subjective measures were collected throughout the laboratory stress session. A mental arithmetic challenge was used to induce stress. In addition, self-reported mood and withdrawal measures were collected multiple times during the ambulatory assessment.

RESULTS

Khat users reported greater negative affect than nonusers. Results from the ambulatory study indicated that withdrawal symptoms were lower during evening hours in the fasting group than in the no-fasting group. Stress-related changes in positive and negative affects were flattened in the fasting group relative to the no-fasting group. Khat users reported reduced blood pressure responses relative to nonusers.

CONCLUSION

These preliminary results demonstrate that fasting is associated with reduced negative affect and withdrawal symptoms in khat users. Khat use was related to blunted blood pressure stress responses, but this was independent of fasting. Due to the small sample size, these results should be replicated with a large sample and comprehensive stress tasks.

Brain Marker Links Stress and Nicotine Abstinence

BACKGROUND

Subjective stress is a well-documented predictor of early smoking relapse, yet our understanding of stress and tobacco use is limited by reliance on self-reported measures of stress. We utilized a validated functional neuroimaging paradigm to examine whether stress exposure during early abstinence alters objective measures of brain function.

METHODS

Seventy-five participants underwent blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) during the Montreal Imaging Stress Task (MIST) on two occasions: once during smoking satiety and once following biochemically confirmed 24-hour abstinence (order counterbalanced). The primary outcome measure was brain response during stress (vs. control) blocks of the MIST, assessed using whole-brain analysis corrected for multiple comparisons using clusters determined by Z ≥ 3.1.

RESULTS

Abstinence (vs. satiety) was associated with significantly increased activation in the left inferior frontal gyrus, a brain region associated with inhibitory control. Abstinence-induced change in brain response to stress was positively associated with change in self-reported stress.

CONCLUSIONS

This study provides objective evidence that the brain response to stress is altered during the first 24 hours of a quit attempt compared to smoking satiety.

IMPLICATIONS

These results point to the potential value of inoculating smokers with stress management training prior to a quit attempt.

Blunted cardiovascular reactivity to acute psychological stress predicts low behavioral but not self-reported perseverance: A replication study

Emerging evidence suggests that individuals with poor behavioral perseverance show low or blunted physiological responses to acute psychological stress. For example, a recent preliminary laboratory study demonstrated that blunted responders give up sooner and take fewer attempts when endeavoring to complete an impossible puzzle, but do not self-report poor perseverance. This present research is a replication of the previous study with an increased sample size, longer recovery periods between tasks and addition of social evaluation to the cold pressor. Participants (147) completed a self-report perseverance questionnaire (Short Grit Scale) and behavioral perseverance tasks (impossible Euler puzzle and socially evaluated cold-pressor (SECPT)). The number of attempts and time spent trying to complete the unsolvable puzzle, and duration of hand submergent during the SECPT, were recorded as behavioral perseverance measures. Difference in blood pressure (BP) and pulse rate (PR) from baseline to a 10-min paced auditory serial addition task (PASAT) were computed as reactivity. As previously, reactivity did not relate to self-reported perseverance and blunted BP reactivity to the PASAT was associated with less time persevering at the unsolvable puzzle. Additionally, blunted BP and PR reactivity to the PASAT related to poorer perseverance during the SECPT. These findings, replicating the previous study, increase confidence that blunted reactivity is a physiological marker of poor behavioral perseverance. Moreover, given that self-reported perseverance does not relate to reactivity, this suggests that blunted responders are not conscious of this detriment in perseverance, but likely need additional support when persistence is critical (e.g., during behavior change).

Estradiol promotes and progesterone reduces anxiety-like behavior produced by nicotine withdrawal in female rats

This study assessed sex differences and the role of ovarian hormones in nicotine withdrawal. Study 1 compared physical signs, anxiety-like behavior, and corticosterone levels in male, intact female, and ovariectomized (OVX) female rats during nicotine withdrawal. Estradiol (E2) and progesterone levels were also assessed in intact females that were tested during different phases of the 4-day estrous cycle. Study 2 assessed the role of ovarian hormones in withdrawal by comparing the same measures in OVX rats that received vehicle, E2, or E2+progesterone prior to testing. Briefly, rats received a sham surgery or an ovariectomy procedure. Fifteen days later, rats were prepared with a pump that delivered nicotine for 14 days. On the test day, rats received saline or the nicotinic receptor antagonist, mecamylamine to precipitate withdrawal. Physical signs and anxiety-like behavior were assessed on the elevated plus maze (EPM) and light-dark transfer (LDT) tests. During withdrawal, intact females displayed greater anxiety-like behavior and increases in corticosterone levels as compared to male and OVX rats. Females tested in the estrus phase (when E2 is relatively low) displayed less anxiety-like behavior and had lower corticosterone levels versus all other phases. Anxiety-like behavior and corticosterone levels were positively correlated with E2 and negatively correlated with progesterone levels. Intact females displaying high E2/low progesterone showed greater anxiety-like behavior and corticosterone levels as compared to females displaying low E2/high progesterone. Lastly, OVX-E2 rats displayed greater anxiety-like behavior than OVX-E2+progesterone rats. These data suggest that E2 promotes and progesterone reduces anxiety-like behavior produced by nicotine withdrawal.

Considering the Microbiome in Stress-Related and Neurodevelopmental Trajectories to Schizophrenia

Early life adversity and prenatal stress are consistently associated with an increased risk for schizophrenia, although the exact pathogenic mechanisms linking the exposures with the disease remain elusive. Our previous view of the HPA stress axis as an elegant but simple negative feedback loop, orchestrating adaptation to stressors among the hypothalamus, pituitary, and adrenal glands, needs to be updated. Research in the last two decades shows that important bidirectional signaling between the HPA axis and intestinal mucosa modulates brain function and neurochemistry, including effects on glucocorticoid hormones and brain-derived neurotrophic factor (BDNF). The intestinal microbiome in earliest life, which is seeded by the vaginal microbiome during delivery, programs the development of the HPA axis in a critical developmental window, determining stress sensitivity and HPA function as well as immune system development. The crosstalk between the HPA and the Microbiome Gut Brain Axis (MGBA) is particularly high in the hippocampus, the most consistently disrupted neural region in persons with schizophrenia. Animal models suggest that the MGBA remains influential on behavior and physiology across developmental stages, including the perinatal window, early childhood, adolescence, and young adulthood. Understanding the role of the microbiome on critical risk related stressors may enhance or transform of understanding of the origins of schizophrenia and offer new approaches to increase resilience against stress effects for preventing and treating schizophrenia.

Social support, social participation, and cardiovascular reactivity to stress in the Midlife in the United States (MIDUS) study

This study tested two hypotheses of associations between dimensions of social connectedness and cardiovascular reactivity to acute stress: (1) high social support predicts diminished cardiovascular responses to stress (i.e., the stress-buffering model of social support), and (2) diminished cardiovascular responses predict lower social participation, a form of motivated behaviour. Participants (N = 606) in the main Midlife in the United States study completed measures of social support and social participation and underwent psychophysiological stress testing. In unadjusted analyses, social support was positively, rather than inversely, associated with reactivity. Results withstood adjustment for several control variables, but not for depressive symptoms, which was associated with diminished reactivity. Further, diminished reactivity was associated with lower social participation, but not in fully adjusted models. No robust evidence was observed for either the stress-buffering model, or for an association between diminished reactivity and lower social participation. The implications for our understanding of links between social connectedness and cardiovascular reactivity are discussed.

A neurobiological correlate of stress-induced nicotine-seeking behavior among cigarette smokers

Stress is known to influence smoking relapse. Experimental studies indicate that acute stress increases nicotine-seeking behavior, yet neurobiological mechanisms remain poorly understood. Herein, we investigated disrupted excitatory neural activity in the dorsolateral prefrontal cortex (dlPFC) as a mechanism of stress-induced nicotine-seeking behavior. Non-treatment-seeking cigarette smokers were screened for psychiatric, medical, and neuroimaging contraindications. Using a double-blind, placebo-controlled, randomized crossover design, participants (N = 21) completed two oral-dosing sessions: stress (yohimbine 54 mg + hydrocortisone 10 mg) vs placebo (lactose 54 mg + lactose 10 mg). During each experimental session, working memory proficiency, dlPFC excitatory neural activity, nicotine-seeking behavior, and subjective effects were measured. dlPFC excitatory neural activity was quantified via glutamate modulation during working memory performance using functional proton magnetic resonance spectroscopy. Nicotine-seeking behavior was assayed using a cigarette puffs vs money choice progressive ratio task. Results indicated that yohimbine + hydrocortisone evoked a sustained physiological stress response (elevated heart rate, blood pressure, saliva cortisol, and saliva α-amylase levels; ps < .05). Relative to placebo levels, acute stress increased nicotine-seeking behavior (ps < .05), disrupted dlPFC glutamate modulation (p = .025), and impaired dlPFC function (working memory proficiency; ps < .05). The stress-induced increase in nicotine-seeking behavior was linearly related to the stress-induced disruption of dlPFC glutamate modulation (R²  = 0.24-0.37; ps < .05). These findings suggest that disrupted dlPFC excitatory neural activity is a neurobiological correlate of acute stress-induced nicotine-seeking behavior. These findings further emphasize the central role of the dlPFC in regulating drug-seeking behavior. Future studies are needed to evaluate interventions to improve dlPFC resilience to acute stress effects, including neurostimulation, working memory training, and "anti-stress" medications.

Hormonal responses in gambling versus alcohol abuse: A review of human studies

The endocrine system plays an essential role in communication between various organs of the body to maintain homeostasis. Both substance use disorders (SUDs) and non-substance abuse disrupt this system and lead to hormonal dysregulations. Here, we focus on the comparison between the function of the endocrine system in gambling disorders and alcohol addiction to understand the commonalities and differences in their neurobiological and psychological underpinnings. We review human research to compare findings on gambling addiction and alcohol dependence pertaining to the dynamic interplay between testosterone and cortisol. Understanding and classifying similarities in hormonal responses between behavioural addiction and SUDs may facilitate development of treatments and therapeutic interventions across different types of addictive disorders, while describing differences may shed light on therapeutic interventions for specific disorders. Although research on gambling addiction is in its infancy, such evaluation may still have a positive effect for addiction research, thereby stimulating discovery of "crossover" pharmacotherapies with benefits for both SUDs and nonsubstance addictions.

American Indian young adults display diminished cardiovascular and cortisol responses to acute psychological stress

American Indian adults are at an increased risk for cardiovascular disease compared with non-Hispanic white adults. Scant research exists examining the underlying physiological and psychological mechanisms associated with these risks. This study aimed to examine possible psychological and physiological stress-related mechanisms related to cardiovascular disease risk in healthy American Indian and non-Hispanic white adults. Forty American Indian (60% female, Mean age = 19.93, SD = 2.08 years) and 45 non-Hispanic white (70% female, Mean age = 20.18, SD = 2.22 years) participants attended an in-person laboratory session. Salivary cortisol and cardiovascular activity were measured before (baseline), during, and after exposure to a 10-minute mental arithmetic task. Compared to non-Hispanic white participants, American Indian had diminished salivary cortisol (p < .001), blood pressure (p's < .001), and heart rate (p = .041) responses to acute psychological stress. These effects could not be accounted for by differences in task performance or self-reported engagement. Previous research has shown that exaggerated responses to stress are associated with increased risk of cardiovascular disease. However, diminished responses to stress are associated with early childhood stress and future adverse behaviors (e.g., addiction, obesity). Diminished reactivity may influence behaviors that can impact future development of cardiovascular disease in American Indian populations.

Stress responding and stress-related changes in cue reactivity in heavy smokers, problem gamblers, and healthy controls

Addictions, both substance and behavioral, have been conceptualized as involving similar biopsychosocial processes with different opportunistic expressions. A maladaptive stress response in combination with craving or urges to engage in the addictive behavior may be among the underlying factors common to behavioral and substance addictions. The current study compared the neuroendocrine (cortisol) and subjective responses to stress of gamblers and smokers to healthy controls. We assessed if participants responded differently to smoking or gambling cues before and after a psychosocial stressor. To this end, the subjective urges/cravings of all participants were measured in response to smoking or gambling cues versus neutral cues, once under normal conditions and again after exposure to a stressor. Salivary cortisol was measured prior to, immediately following, and 10 minutes after conclusion of the stressor. Smokers and gamblers showed a similar blunted cortisol response to the acute stressor that differed from the control group's response. Following a stressor, subjective craving in smokers increased whereas gamblers' urges decreased. In smokers, a blunted cortisol and subjective stress response were related to increased urges. In contrast, for gamblers, changes in cortisol levels were unrelated to urges, and higher subjective stress was associated with decreased urges. In conclusion, individuals with a substance and a behavioral addiction share common patterns of reactivity to stress. However, while the stressor enhanced cue-related craving in smokers, it generally had the opposite effect on gamblers. Further research is necessary to elucidate the complicated patterns of similarities and differences that underlie substance and behavioral addictions.

Subjective response to intranasal nicotine administration in oral contraceptive users and naturally-cycling women

INTRODUCTION

Approximately half of premenopausal women who smoke cigarettes also use hormonal contraceptives, with most using oral contraceptives (OCs). While research on the effects of endogenous hormones on smoking-related outcomes continues to expand, little is known about the influence of OCs on similar outcomes. We sought to explore differences in the subjective response to nicotine by OC use after stratifying by testing condition (e.g., smoking status).

METHODS

Participants were regular (≥5 cigarettes/day) smokers, classified into OC and naturally cycling (NC) groups. All participants completed four total lab sessions by smoking status (ad libitum smoking, acute smoking abstinence) and anticipated progesterone level (low progesterone week (LPW), high progesterone week (HPW)). Each lab session included self-administration of intranasal nicotine (Time 0 min), assessment of subjective response via the Subjective State Scale (-30 and + 5 min).

RESULTS

Compared to the NC group (n = 28), the OC group (n = 14) was younger (26.2 ± 1.1 versus 24.2 ± 1.1; p < 0.001) and had a lower Fagerström Test for Nicotine Dependence score (3.4 ± 0.5 versus 2.6 ± 0.5; p = 0.011). Progesterone-to-estradiol ratios varied significantly by group at three of the four time points (p < 0.05). During ad libitum smoking, the OC group had significantly lower craving after nicotine administration than the NC group (1.93 ± 0.33 versus 2.89 ± 0.23; p = 0.024). No other significant differences in subjective response were identified.

CONCLUSIONS

Despite significantly different hormone levels, group differences in subjective response to nicotine were relatively few. Additional research is needed to elucidate the mechanisms involved in these observations, as well as explore how they may influence cessation in women.

Brain Region-Specific nAChR and Associated Protein Abundance Alterations Following Chronic Nicotine and/or Menthol Exposure

The identification of biomarkers that are altered following nicotine/tobacco exposure can facilitate the investigation of tobacco-related diseases. Nicotinic acetylcholine receptors (nAChRs) are pentameric cation channels expressed in the mammalian central and peripheral nervous systems and the neuromuscular junction. Neuronal nAChR subunits (11) have been identified in mammals (α2-7, α9-10, β2-4). We examined changes in β2 nAChR subunit protein levels after chronic nicotine, (±)-menthol, or nicotine co-administered with (±)-menthol in nine murine brain regions. Our investigation of β2 nAChR subunit level changes identified the hypothalamus as a novel region of interest for menthol exposure that demonstrated increased β2 nAChR levels after (±)-menthol plus nicotine exposure compared to nicotine exposure alone. Using mass spectrometry, we further characterized changes in membrane protein abundance profiles in the hypothalamus to identify potential biomarkers of (±)-menthol plus nicotine exposure and proteins that may contribute to the elevated β2 nAChR subunit levels. In the hypothalamus, 272 membrane proteins were identified with altered abundances after chronic nicotine plus menthol exposure with respect to chronic nicotine exposure without menthol. A comprehensive investigation of changes in nAChR and non-nAChR protein expression resulting from (±)-menthol plus nicotine in the brain may establish biomarkers to better understand the effects of these drugs on addiction and addiction-related diseases.

Early-Life Adversity and Blunted Stress Reactivity as Predictors of Alcohol and Drug use in Persons With COMT (rs4680) Val158Met Genotypes

BACKGROUND

Risk for alcoholism may be enhanced by exposure to early-life adversity (ELA) in persons with genetic vulnerabilities. We examined ELA in the presence of a common variant of the gene for the enzyme catechol-O-methyltransferase (COMT, Val158Met, rs4680) in relation to cortisol reactivity, the onset of early drinking, and experimentation with drugs.

METHODS

Saliva cortisol reactivity to speech and mental arithmetic stress was measured in 480 healthy young adults (23.5 years of age, 50% females) who experienced either 0, 1, or ≥ 2 forms of ELA during childhood and adolescence, provided information on use of alcohol and recreational drugs, and were genotyped for the Val158Met polymorphism.

RESULTS

ELA led to progressively smaller cortisol responses in the Met/Met and Val/Met allele groups but to progressively larger responses in Val homozygotes, F = 3.29, p = 0.011. ELA independently predicted earlier age at first drink, F = 14.2, p < 0.0001, with a larger effect in Met-allele carriers, F = 13.95, p < 0.00001, and a smaller effect in Val homozygotes, F = 4.14, p = 0.02. Similar effects were seen in recreational drug use. Cortisol reactivity was unrelated to drinking behavior or drug experimentation.

CONCLUSIONS

ELA leads to blunted stress reactivity and, independently, contributes to potentially risky drinking and drug-use behaviors in persons carrying 1 or 2 copies of the COMT 158Met allele. The results reinforce the impact of early experience on the stress axis and on risky behaviors, and they point to the 158Met allele as conveying a vulnerability to the early environment.

Blunted stress reactivity reveals vulnerability to early life adversity in young adults with a family history of alcoholism

BACKGROUND AND AIMS

People with blunted stress reactivity have poor impulse control and also show increased risk for alcoholism. Exposure to early life adversity (ELA) contributes to blunted reactivity, but individual differences in susceptibility to ELA are not well understood. This study aimed to determine whether exposure to ELA has a greater impact on stress reactivity in young adults with a family history of alcoholism (FH+) compared with young adults with no family history of alcoholism (FH-).

DESIGN

Observational study using linear modeling.

SETTING

Oklahoma, USA.

PARTICIPANTS

Seven hundred and nine young adults (398 females) recruited through community advertisement.

MEASUREMENTS

We obtained heart rates and cortisol levels in subjects while undergoing public speaking and mental arithmetic stress compared with a resting control day (1418 test sessions). ELA was quantified as 0, 1 or > 1 adverse events experienced by age 15 years. FH+ people had one or two parents with an alcohol use disorder, and FH- controls had no such history for two generations.

FINDINGS

Increasing levels of ELA predicted progressive blunting of cortisol and heart rate reactivity for the whole sample (Fs = 4.57 and 4.70, Ps ≤ 0.011), but examination by FH status showed that the effect of ELA was significant only among FH+ (Fs ≥ 3.5, Ps < 0.05) and absent in FH- (Ps > 0.40). This difference in ELA impact was not explained by the cortisol diurnal cycle or subjective evaluation of the stressors.

CONCLUSIONS

People with a family history of alcoholism appear to be vulnerable, in terms of changes to physiological stress response, to the impact of exposure to early life adversity while people with no family history of alcoholism appear to be resilient. Blunted stress reactivity may reflect differential vulnerability to early life adversity in young adults with a family history of alcoholism.

The role of endogenous pituitary adenylyl cyclase activating polypeptide (PACAP) in nicotine self-administration, reward and aversion

Pituitary adenylyl cyclase activating polypeptide (PACAP) and its receptors (PAC1, VPAC1, and VPAC2) are localized in brain regions implicated in stress response, reward seeking and aversive responses, raising the possibility that PACAP may be involved in motivational effects of nicotine. To test this hypothesis, we used two-bottle choice (TBC) and place conditioning paradigms and assessed if nicotine preference or conditioned place preference (CPP) or aversion (CPA) induced by nicotine would be altered in mice lacking PACAP compared to their wild-type controls. In the TBC paradigm, mice had access to two water bottles during the first week and then one of the water bottles was switched to nicotine solution (20, 40 and then 80 μg/mL). The volume of water and nicotine consumed was measured every day. In the place conditioning paradigm, mice were tested for baseline place preference on day 1, received conditioning with saline versus a low (0.25) or high (1 mg/kg) dose nicotine and, respectively, tested for CPP or CPA 24 h following the last conditioning. We discovered that mice lacking PACAP compared to their wild-type controls exhibited more preference for nicotine over water in the TBC paradigm, particularly at the two higher concentrations of nicotine. While the rewarding action of the low dose nicotine was not altered in mice lacking PACAP, the aversive effect of the high dose nicotine was blunted in these mice compared to their wild-type controls. The present results suggest that endogenous PACAP may play a functional role in nicotine preference and its aversive effect.

Diminished cardiovascular stress reactivity is associated with lower levels of social participation

Diminished cardiac reactions to acute psychological stress are associated with adverse behavioral and health-relevant outcomes. It has been proposed that diminished cardiac reactivity may be a marker for deficits in motivational functioning both at the biological and behavioral levels. Social participation reflects the frequency with which individuals participate in social events and has motivational components. As such, it is a distinct construct from other constructs such as social integration, which measures the number of social roles an individual has. Additionally, lower levels of social participation and diminished reactivity have been associated with similar adverse health outcomes. Therefore, it is possible that diminished cardiac reactivity is associated with lower levels of social participation. We aimed to examine whether diminished cardiovascular reactivity in response to an acute lab stressor was associated with reported social participation. The analyses were conducted using publicly available data from the Pittsburgh Cold Study 3 (PCS3). The PCS3 was a prospective viral-challenge study, which included participants completing an in-lab social evaluative stressor (N = 202, Age = M = 29.71, SD = 10.66) and measuring cardiovascular responses at baseline and in response to the stressor. Separate regression analyses for each cardiovascular variable (SBP, DBP, MAP, and HR) demonstrated that lower cardiovascular reactivity was associated with less social participation. These associations were still evident following adjustment for respective baseline cardiovascular levels, age, sex, race, depressive symptomology, body mass index, socioeconomic status, smoking status, and levels of social integration (R2 changes: ≥ 0.017; ps ≤ 0.02) The findings provide initial evidence that blunted cardiac reactivity may be a precursor to low levels of social participation.

Smoking-induced changes in leptin serum levels and c/EBPalpha-related methylation status of the leptin core promotor during smoking cessation

Previous studies have provided evidence of an association between serum leptin levels and smoking as well as craving during smoking cessation. As promoter methylation also regulates leptin expression, we investigated the leptin gene promoter region of smokers before and after smoking cessation. Since leptin's core promoter region contains an essential c/EBPalpha transcription binding site, we narrowed our investigation to C-300 (-300 base pairs from the transcription start site) of that binding site. Female smokers showed hypermethylation of C-300 compared to non-smokers. Global methylation status is associated with higher craving and the degree of dependence in female smokers. Serum leptin levels in female smokers were significantly higher than in non-smokers. These findings support previous results and, for the first time, point to a pathophysiological role of c/EBPalpha-related C-300 methylation in tobacco dependence.

Drug-induced stress responses and addiction risk and relapse

A number of studies have assessed the effects of psychoactive drugs on stress biology, the neuroadaptations resulting from chronic drug use on stress biology, and their effects on addiction risk and relapse. This review mainly covers human research on the acute effects of different drugs of abuse (i.e., nicotine, cannabis, psychostimulants, alcohol, and opioids) on the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS) responses. We review the literature on acute peripheral stress responses in naïve or light recreational users and binge/heavy or chronic drug users. We also discuss evidence of alterations in tonic levels, or tolerance, in the latter relative to the former and associated changes in the phasic stress responses. We discuss the impact of the stress system tolerance in heavy users on their response to drug- and stress-related cue responses and craving as compared to control subjects. A summary is provided of the effects of glucocorticoid responses and their adaptations on brain striatal and prefrontal cortices involved in the regulation of drug seeking and relapse risk. Finally, we summarize important considerations, including individual difference factors such as gender, co-occurring drug use, early trauma and adversity and drug use history and variation in methodologies, that may further influence the effects of these drugs on stress biology.

Stressful life events are associated with perinatal cigarette smoking

Perinatal smoking, including smoking during pregnancy and postpartum smoking relapse, is a persistent public health problem. While childhood trauma has been linked to perinatal smoking, less is known about the association with more proximal stressful life events (SLEs). The objective of this study was to examine the association between SLEs that occurred during the year prior to childbirth with perinatal smoking. Using the Pregnancy Risk Assessment Monitoring System 2009-2011, perinatal smoking was assessed at three time points: (1) three months prior to pregnancy, (2) the last three months of pregnancy, and (3) two to six months postpartum. Survey respondents endorsed up to 13 SLEs (i.e., death of someone close). SLEs were analyzed individually, as well as using a cumulative score (range 0-13). Weighted analyses included unadjusted and adjusted logistic regression. Among those who smoked prior to pregnancy (n = 15,316), 48% (n = 7308) reported quitting smoking during pregnancy. Of those, 44% (n = 3126) reported postpartum smoking relapse. A total of 11 SLEs were associated with smoking during pregnancy and 2 SLEs were associated with postpartum smoking relapse. The odds of continued smoking during pregnancy was 12% higher for each SLE endorsed (adjusted odds ratio [aOR] = 1.12, 95% confidence interval [CI]: 1.09, 1.15) and this association was attenuated in relation to the odds of postpartum smoking relapse (aOR = 1.03, 95% CI: 0.99, 1.08). SLEs are associated with perinatal smoking. Additional research is needed to elucidate the mechanisms of action and to develop interventions specific to the needs of women who experience SLEs.

Impact of early life adversity on the stress biobehavioral response during nicotine withdrawal

Exposure to early life adversity (ELA) is associated with increased subsequent risk for addiction and relapse. We examined changes in psychobiological responses to stress in dependent smokers and nonsmoking controls and evaluated how history of early adversity may exacerbate acute changes during nicotine withdrawal and acute stress. Smokers were randomly assigned to one of two conditions; 24 h withdrawal (66 smokers) from smoking and all nicotine-containing products or smoking ad libitum (46 smokers) prior to an acute laboratory stress induction session; and 44 nonsmokers provided normal referencing. The laboratory session included a baseline rest, stress and recovery periods. Plasma and saliva samples for the measurement stress hormones and cardiovascular and self-report mood measures were collected multiple times during the session. Multivariate analysis confirmed that all groups showed stress-related increases in negative mood, cardiovascular measures and stress hormones, particularly smokers in the withdrawal condition. Individuals with high ELA showed greater adrenocorticotropic hormone (ACTH), but lower plasma and salivary cortisol levels, than those with low ELA. Cortisol differences were abolished during tobacco withdrawal. These findings demonstrate that ELA moderates the effects of withdrawal on stress-related biobehavioral changes.

Happiness as a Buffer of the Association Between Dependence and Acute Tobacco Abstinence Effects in African American Smokers

Introduction

African American (AA) smokers are at disproportionate risk of tobacco dependence, utilizing smoking to regulate stress, and poor cessation outcomes. Positive emotional traits may function as coping factors that buffer the extent to which dependence increases vulnerability to adverse responses to acute tobacco abstinence (ie, tobacco withdrawal). This laboratory study examined subjective happiness (SH; dispositional orientation towards frequent and intense positive affect [PA] and life satisfaction) as a moderator of the relation between tobacco dependence and subjective and behavioral abstinence effects among AA smokers.

Methods

AA smokers (N = 420, 39.0% female) completed self-report measures of tobacco dependence and SH followed by two counterbalanced experimental sessions (nonabstinent vs. 16-hour abstinent) involving self-report measures of composite withdrawal, urge to smoke, and mood, and a behavioral smoking task in which participants could: (1) earn money to delay smoking reinstatement, and (2) subsequently purchase cigarettes to smoke.

Results

Tobacco dependence was positively associated with increased abstinence effects in composite withdrawal, urge to smoke, PA, and latency to smoking reinstatement (ps < .04). SH significantly moderated the relation between dependence and abstinence-induced increases in composite withdrawal (β = -.17, p < .001), such that the predictive power of dependence on withdrawal severity grew proportionately weaker as levels of SH increased.

Conclusions

SH may insulate against adverse effects of dependence on withdrawal during acute smoking abstinence, particularly withdrawal symptom clusters that are craving- and mood-based. Consideration of positive emotional traits as stress-coping factors in the dependence-withdrawal link may be warranted in research and practice with AA smokers.

Implications

The current study contributes to a growing body of literature examining the potentially advantageous role of positive emotional traits to smokers. We do so by identifying a relatively understudied psychological construct within tobacco research-subjective happiness-that may suppress the extent to which more severe tobacco dependence increases risk for subjective withdrawal-related distress during acute smoking abstinence in AA smokers. In doing so, the study provides a primer for future targeting of subjective happiness and other positive emotional traits as means to understand and treat acute tobacco abstinence effects among dependent AA smokers.

The influence of smoking and cessation on the human reproductive hormonal balance

Smoking is the most widespread substance dependence in the world. Nicotine and some other components of the cigarette smoke cause various endocrine imbalances, and have negative effects on pituitary, thyroid, adrenal, testicular and ovarian functions. Here, we examined studies that describe the influence of smoking and smoking cessation on the male and female reproductive systems. We also focused on studies providing an account of differences in cessation success rates between men and women. In men, the most common effects associated with smoking are erectile dysfunction and decreasing spermiogram quality. Several groups have studied the effects of cigarette smoking on testosterone levels in men. However, the results have been conflicting. In women, nicotine has an anti-estrogen effect and increases the ratio of androgens to estrogens throughout life. Beside nicotine, other cigarette toxins also cause dysregulation of reproductive and hormonal system, and essentially influence the probability of a successful pregnancy not only in cases of assisted reproduction but also in healthy women. Tobacco addiction is one of the forms of addiction that are generally thought to be different for men and for women. Women are less successful than men in quitting smoking, and nicotine replacement therapy is less effective in female smokers. We also summarize recent studies that have indicated possible reasons.

Mediational Pathways Among Trait Impulsivity, Heroin-use Consequences, and Current Mood State

BACKGROUND

This study examined whether lifetime heroin-use consequences mediate the relationship between trait impulsivity and three current mood outcomes: depression symptoms, stress levels, and perception of life events.

METHOD

Regular heroin users (N = 163) were assessed using the Barratt Impulsiveness Scale (BIS-11) to measure trait impulsivity; a standardized Drug History and Use Questionnaire to measure lifetime adverse consequences of heroin use; Beck Depression Inventory II to measure current depression symptoms; Stress subscale of the Depression Anxiety Stress scale; and Hassles and Uplifts scale to measure perception of life events.

RESULTS

BIS-11 Attentional and Motor impulsivity were positively related to number of adverse heroin-use consequences, depression symptoms, and stress level, and negatively associated with positive perception of events. A greater number of heroin-use consequences was related to more depression symptoms, higher stress, more negative perception of events, injection heroin use, and earlier ages of first and regular heroin use. In six mediation models, lifetime heroin-use consequences partially mediated relationships between two trait impulsivity domains (Attentional, Motor) and current mood measures (depression symptoms, stress, perception of events).

CONCLUSIONS

The present findings suggest that current negative mood can be a response to the accumulated burden of heroin-use consequences, particularly in the presence of high trait impulsivity.

Central and Peripheral Biomarkers of Stress Response for Addiction Risk and Relapse Vulnerability

Substance use disorders (SUDs) are marked by heterogeneity in clinical symptomatology and high relapse rates following treatment. Here, we describe specific peripheral and central stress responses associated with the pathophysiology of SUDs. We outline potential stress response measures, including hypothalamus-pituitary-adrenal axis markers, autonomic responses, and central structural and functional brain alterations that could be exploited as putative biomarkers in SUDs. We posit that stress responses can be predictive of both the development of SUDs and their high relapsing nature. We examine their potential as candidate biomarkers, as well as the remaining challenges in developing and implementing their application for the prevention and treatment of SUDs.

Stress and Addiction: When a Robust Stress Response Indicates Resiliency

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.