Depression and nicotine: preclinical and clinical evidence for common mechanisms

Theobromine synergizes with nicotine to enhance animal motor abilities and cognitive function

The societal consensus on the need for smoking cessation is well-established, yet the number of tobacco users continues to rise. This trend is largely driven by the potent physiological effects of nicotine, which significantly increase the likelihood of tobacco use initiation. Certain compounds found in everyday foods, such as theobromine and caffeine in cocoa products, also exhibit psychostimulatory properties. However, comprehensive studies on the effects of consuming these compounds in the context of tobacco use are limited. This study investigates the role of theobromine, a primary active component in cocoa, in modulating the positive physiological effects of nicotine and explores the underlying mechanisms. Our findings reveal that while low doses of theobromine do not alter nicotine's addictive properties, they amplify its positive physiological effects. Notably, theobromine's impact on nicotine varies significantly between the hippocampus and cerebellum, highlighting region-specific interactions.

Gender differences in the relationship between nicotine exposure and symptoms of depression

BACKGROUND

Tobacco-derived nicotine exposure is linked to depression. However, the associations of nicotine and its metabolites with symptoms of depression, particularly concerning gender differences, remain underexplored.

METHODS

The characteristics and total nicotine equivalents (TNE) of 1001 subjects were determined. The association between the TNE and symptoms of depression, accounting for gender differences, was investigated using generalized linear models and subgroup analyses.

RESULTS

Men exhibited significantly greater levels of the nicotine exposure indicators TNE2, TNE3, TNE6, and TNE7 (P < 0.005). A significantly greater percentage of women (23.45 %) than men (9.81 %) exhibited symptoms of depression (P < 0.0001). In women, the relationship between the TNE and depression was reflected by a U-shaped curve with significant inflection points, particularly for TNE3, TNE6, and TNE7. Furthermore, in women, concentrations above 48.98 nmol/mL for TNE3, 53.70 nmol/mL for TNE6, and 57.54 nmol/mL for TNE7 were associated with 154 %, 145 %, and 138 % increases in the risk of depression, respectively. In contrast, these associations did not reach significance among men.

LIMITATIONS

The cross-sectional design limits the ability to infer causality between nicotine exposure and depressive symptoms. Larger-scale studies are needed to confirm these findings.

CONCLUSIONS

Gender could be a significant factor influencing the relationship between nicotine exposure levels and symptoms of depression. The impact of nicotine exposure on symptoms of depression should be particularly considered among women.

IMPLICATIONS

This study revealed the complex relationship between tobacco-related nicotine exposure and depressive symptoms, with a particular focus on gender differences. Our results revealed a distinct U-shaped correlation between total nicotine equivalents and depression in women, which differed from that in men. These findings emphasize the importance of tailoring clinical approaches to address nicotine exposure and manage depressive symptoms based on gender.

Association of diastolic and systolic blood pressure with depression: a cross-sectional study from NHANES 2005-2018

Background

Many studies worldwide have reported the association between mental health and blood pressure, but the results are mixed, and even contradictory. We aim to investigate the relationship between systolic and diastolic blood pressure and depression in the entire US population.

Methods

This study analyzed cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018. All adults completed 3-4 blood pressure measurements after sitting quietly for 5 minutes. Depression was diagnosed based on the Patient Health Questionnaire (PHQ-9), with a score ≥10 defined as depression. Weighted logistic regression and restricted cubic splines (RCS) were used to assess the relationship between blood pressure and depression. Two-piecewise linear regression was used to determine the inflection point. Additionally, subgroup analyses and interaction tests were conducted to identify potential subgroups. Finally, two sensitivity analyses were conducted.

Results

A total of 26,581 American adults were included, with a mean age of 47.2 years, of whom 13,354 (49.54%) were male; 2,261 individuals were defined as depressed, with a weighted prevalence of 7.41%. All participants' mean systolic blood pressure (SBP) was 121.7 mmHg, and the mean diastolic blood pressure (DBP) was 70.9 mmHg. RCS showed a nonlinear association between SBP and depression, while DBP showed a positive linear association with depression. Two-piecewise linear regression showed that the inflection point of the association between SBP and depression was 129.7 mmHg. Weighted logistic regression showed that after fully adjusting for depression-related risk factors, there was a significant positive correlation between per 10 mmHg increase in DBP and depression (OR: 1.06, 95% CI: 1.00-1.12, P=0.04); however, only on the left side of the inflection point, SBP tended to decrease the odds of depression (P =0.09). Furthermore, interaction analysis showed that the association between DBP and depression was significantly stronger in cancer patients (P for interaction=0.02); on the left side of the inflection point (<129.7 mmHg), current smokers also significantly interacted with SBP (P for interaction=0.018). Finally, two sensitivity analyses also supported our findings.

Conclusion

In the adult population of the United States, there is a positive linear association between DBP and depression, while the association between SBP and depression exhibits a significant threshold effect, maintaining SBP at 129.7 mmHg is associated with the lowest prevalence of depression.

Associations Between Cardiovascular Health (Life's Essential 8) and Mental Disorders

BACKGROUND

Mental health was closely associated with cardiovascular disease (CVD). We aimed to investigate the association between cardiovascular health (CVH), as defined by Life's Essential 8 (LE8), and the presence of depression and anxiety.

HYPOTHESIS

We hypothesized that CVH, as defined by LE8, was negatively associated with the prevalence of depression and anxiety.

METHODS

A cross-sectional study was conducted on participants (≥ 20 years old) from the National Health and Nutrition Examination Survey (NHANES). The LE8 score (ranging from 0 to 100) was composed of the health behavior score and the health factor score, which were further categorized into three levels as follows: low (0-49), moderate (50-79), and high (80-100). Weighted multivariable logistic regressions and restricted cubic splines were utilized to assess the association between LE8 and mental disorders.

RESULTS

Among the 13 028 participants included in this research, 1206 were determined to have depression symptoms and 2947 were determined to have anxiety symptoms. In the weighted and adjusted model, LE8 was negatively associated with the prevalence of depression (odds ratio [OR], 95% confidence interval [CI]: 0.61, 0.58-0.65) and anxiety (OR, 95% CI: 0.78, 0.75-0.81). Furthermore, a nonlinear dose-response relationship was observed between LE8 and anxiety.

CONCLUSIONS

CVH defined by the LE8 was independently and negatively associated with the prevalence of depression and anxiety. Interventions targeting LE8 components may improve both CVH and mental health.

The double-edged nature of nicotine: toxicities and therapeutic potentials

Nicotine is the primary addictive component of cigarette smoke and is associated with various smoking-related diseases. However, recent research has revealed its broader cognitive-enhancing and anti-inflammatory properties, suggesting its potential therapeutic applications in several conditions. This review aims to examine the double-edged nature of nicotine, encompassing its positive and negative effects. We provide a concise overview of the physiochemical properties and pharmacology of nicotine, including insights into nicotine receptors. Therefore, the article is divided into two main sections: toxicity and therapeutic potential. We comprehensively explored nicotine-related diseases, focusing on specific signaling pathways and the underlying mechanisms that contribute to its effects. Furthermore, we addressed the current research challenges and future development perspectives. This review aims to inspire future researchers to explore the full medical potential of nicotine, which holds significant promise for the clinical management of specific diseases.

Nicotine neurotoxicity exacerbation following engineered Ag and Cu (50-60 nm) nanoparticles intoxication. Neuroprotection with nanowired delivery of antioxidant compound H-290/51 together with serotonin 5-HT3 receptor antagonist ondansetron

Nicotine abuse is frequent worldwide leading to about 8 millions people die every year due to tobacco related diseases. Military personnel often use nicotine smoking that is about 12.8% higher than civilian populations. Nicotine smoking triggers oxidative stress and are linked to several neurodegenerative diseases such as Alzheimer's disease. Nicotine neurotoxicity induces significant depression and oxidative stress in the brain leading to neurovascular damages and brain pathology. Thus, details of nicotine neurotoxicity and factors influencing them require additional investigations. In this review, effects of engineered nanoparticles from metals Ag and Cu (50-60 nm) on nicotine neurotoxicity are discussed with regard to nicotine smoking. Military personnel often work in the environment where chances of nanoparticles exposure are quite common. In our earlier studies, we have shown that nanoparticles alone induces breakdown of the blood-brain barrier (BBB) and exacerbates brain pathology in animal models. In present investigation, nicotine exposure in with Ag or Cu nanoparticles intoxicated group exacerbated BBB breakdown, induce oxidative stress and aggravate brain pathology. Treatment with nanowired H-290/51 a potent chain-breaking antioxidant together with nanowired ondansetron, a potent 5-HT3 receptor antagonist significantly reduced oxidative stress, BBB breakdown and brain pathology in nicotine exposure associated with Ag or Cu nanoparticles intoxication. The functional significance of this findings and possible mechanisms of nicotine neurotoxicity are discussed based on current literature.

Nicotine's effect on cognition, a friend or foe?

Tobacco smoking is a preventable cause of morbidity and mortality throughout the world. Smoking comes in form of absorption of many compounds, among which nicotine is the main psychoactive component of tobacco and its positive and negative reinforcement effects are proposed to be the key mechanism for the initiation and maintenance of smoking. Growing evidence suggests that the cognitive enhancement effects of nicotine may also contribute to the difficulty of quitting smoking, especially in individuals with psychiatric disorders. In this review, we first introduce the beneficial effect of nicotine on cognition including attention, short-term memory and long-term memory. We next summarize the beneficial effect of nicotine on cognition under pathological conditions, including Alzheimer's disease, Parkinson's disease, Schizophrenia, Stress-induced Anxiety, Depression, and drug-induced memory impairment. The possible mechanism underlying nicotine's effect is also explored. Finally, nicotine's detrimental effect on cognition is discussed, including in the prenatal and adolescent periods, and high-dose nicotine- and withdrawal-induced memory impairment is emphasized. Therefore, nicotine serves as both a friend and foe. Nicotine-derived compounds could be a promising strategy to alleviate neurological disease-associated cognitive deficit, however, due to nicotine's detrimental effect, continued educational programs and public awareness campaigns are needed to reduce tobacco use among pregnant women and smoking should be quitted even if it is e-cigarette, especially for the adolescents.

Adolescent nicotine and footshock exposure augments adult nicotine self-administration and drug-seeking without affecting baseline anxiety-like behaviour or stress responsivity in male rats

RATIONALE

Over the past decade, adolescent cigarette smoking has been declining. However, adolescent nicotine consumption via electronic cigarettes is rapidly gaining popularity. Earlier onset nicotine use is associated with increased risk of dependence. A bidirectional relationship between nicotine and stress exists; perceived stress is a predictor for nicotine use, and stress reduction is a commonly reported reason for using nicotine.

OBJECTIVES

We assessed the prolonged impact of adolescent high-dose nicotine and/or footshock exposure on adult nicotine self-administration, anxiety-like behaviour, and hormonal responsivity.

METHODS

During adolescence (postnatal day [P]28-56) male Sprague-Dawley rats were assigned to one of five groups: saline (SALPRE: 1 ml/kg, SC, every day), nicotine (NICPRE: 1 mg/kg, SC, alternating daily with saline; 14 total nicotine injections), footshock (SHOCKPRE: 8 of 0.5 s, 0.8 mA alternating sessions; saline every day), or combination nicotine and footshock (NIC+SHOCK: concurrent and alternating daily with saline, or NIC-SHOCK: alternating with saline on shock sessions). On P70, one cohort underwent spontaneous intravenous nicotine self-administration (0.03 mg/kg/infusion); another cohort was assessed for open-field behaviour (P71), then corticosterone (CORT) response to nicotine or footshock in adulthood (P72-73).

RESULTS

Intermittent adolescent nicotine or footshock alone (NICPRE and SHOCKPRE) did not potentiate adult spontaneous nicotine intake compared to SALPRE. However, both combination groups (NIC+SHOCK, NIC-SHOCK) showed increased adult nicotine consumption without associated differences in baseline anxiety-like behaviour or CORT response.

CONCLUSIONS

Adolescent nicotine and footshock stressors have a synergistic effect on adult nicotine consumption, enhancing nicotine intake. Avenues toward reducing stress in adolescent nicotine users may provide opportunities to reduce vulnerability to adult nicotine consumption.

Incidence of depressive symptoms and its association with sociodemographic factors and lifestyle-related behaviors among Brazilian university students

Entering university brings on changes in lifestyle and psychological stress and has been associated with increased risk of 1988 in college students. This study aimed to investigate the incidence of depressive symptoms and associated sociodemographic and lifestyle factors among university students. A dynamic cohort of freshmen was followed up for three years, starting at their entry to university (baseline) and then annually. A structured auto administered questionnaire was applied to obtain information on age, sex, economic class, living situation, smoking and drinking, sedentary and sleep behaviors, and change in physical activity after university admission. Depressive symptoms were assessed using the Patient Health Questionaire-9. Incidence and incidence rate of depressive symptoms were calculated. Poisson Regression with robust variance was used to identify risk factors associated to these disorders. A total of 1,034 students without depressive symptoms at baseline were investigated. The overall incidence of depressive symptoms was 28.3% and the incidence rate (IR) was 2.12, being greater for females (2.75) than males (1.65). The IR decreased over time for both males (from 2.61 to 0.41) and females (from 4.25 to 0.54). A greater risk of depressive symptoms was observed for younger male students compared to those ≥20 years old (IRR_adj = 1.64) and for women who reported concomitant use of alcohol and tobacco compared to those that reported no smoking and no alcohol consumption. For both males (IRR_adj = 2.80) and females (IRR_adj = 1.91), severe stress level was associated with greater risk of depressive symptoms when compared to mild stress level. Depressive Symptoms occurred more significantly in females, in the early years of undergraduate course, in males <20 years old, and among those with high stress level. Understanding the possible causes of depression is essential to promote mental health and well-being among college student.

Depressive symptoms predict smoking cessation in a 20-year longitudinal study of adult twins

Depression has been suggested to hinder smoking cessation, especially when co-occurring with nicotine dependence. The study aimed to examine the longitudinal association of depressive symptoms with smoking cessation among daily smokers. The study utilized adult Finnish twin cohort where 1438 daily smokers (mean age: 38.3, range: 33-45) in 1990 were re-examined for their smoking status in 2011. We assessed baseline depressive symptoms with the Beck Depression Inventory, and the self-reported smoking status at follow-up. The methods included multinomial logistic regression and time to event analyses, adjusted for multiple covariates (age, sex, marital status, social class, heavy drinking occasions, and health status) and smoking heaviness at baseline assessed by cigarettes per day (CPD). Additionally, within-twin-pair analyses were conducted. Results indicated that moderate/severe depressive symptoms at baseline were associated with a lower likelihood of smoking cessation two decades later. Adjusting for covariates, those with moderate/severe depressive symptoms (vs. no/minimal depressive symptoms) had 46% lower likelihood of quitting (relative risk ratio, RRR = 0.54, 95% CI: 0.30-0.96). After including CPD, the association of depressive symptoms with smoking cessation attenuated modestly (RRR = 0.62, 95% CI: 0.34-1.12). Further, time to event analysis for quitting year since baseline yielded similar findings. In the within-pair analysis, depressive symptoms were not associated with quitting smoking. The results suggest that reporting more depressive symptoms is associated with a lower likelihood of smoking cessation during a 20-year period. The baseline amount of smoking and familial factors partly explain the observed association. Smoking cessation programs should monitor depressive symptoms.

Reducing the relative value of cigarettes: Considerations for nicotine and non-nicotine factors

Despite notable progress in recent decades, cigarette smoke persists as a leading cause of premature death and preventable disease. To weaken the link between nicotine reinforcement and the toxicity associated with combusted tobacco, the United States Food and Drug Administration is considering a product standard targeting cigarette nicotine content. In this review, we summarize research assessing the potential impacts of reducing nicotine in cigarettes. Evidence to date suggests cigarette smoking, toxicant exposure and dependence would decline following substantial reductions in nicotine content. However, reduced nicotine content may not eliminate smoking entirely. Regulatory efforts that shape the nicotine and tobacco marketplace should consider that non-nicotine reinforcing factors and decision-making biases can contribute to the value of smoking. The impact of reducing nicotine in cigarettes will likely depend on the alternative nicotine products available to current smokers. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.

Arab Men and Women's Conceptualization of Mental Health and Depression: A Qualitative Study from the Middle East

Cardiovascular diseases are the leading cause of death worldwide. Among cardiovascular patients, depression is associated with an increased morbidity and mortality. Understanding how depression is conceptualized from cardiovascular patients' perspective can help with prevention, early detection, and treatment for depression. This might reduce cardiovascular morbidity and mortality, and save health care costs. To the best of our knowledge, there is no study in the Gulf region exploring depression among Arab cardiovascular patients. The purpose of this exploratory ethnographic qualitative research is to investigate how Arab male and female patients with cardiovascular disease conceptualize mental health and depression. Two theoretical frameworks guided this research: (1) The Ecological Perspective, and (2) Kleinman's Explanatory Model of Health and Illness. Using maximum variation purposive sampling, thirty (30) male and twenty-five (25) female, self-identified, Arab cardiovascular patients were recruited as research participants. Individual in-depth interviews were conducted using a semi-structured questionnaire. Thematic analysis was performed to generate themes. Nvivo 10, a qualitative data analysis software, was used to organize the narrative data. The participants in this study placed great emphasis on the manifestations of mental illness and their impact on both themselves and their families. Four major themes were identified from their narratives: psychological and physical disturbances; unfavorable personal characteristics; work issues and financial constraints; lack of family and social support. The knowledge generated in this study might help increase awareness, prevention of and treatment for depression among cardiovascular patients in Qatar. The findings from this study can also be used to inform a multi-disciplinary and multi-sectoral intervention approach that is contextualized to meet the mental health care needs of Arab cardiovascular patients, thus reducing cardiovascular diseases morbidity and mortality in Qatar and the Gulf region.

Nondaily Cigarette Smoking Is Increasing Among People With Common Mental Health and Substance Use Problems in the United States: Data From Representative Samples of US Adults, 2005-2014

OBJECTIVE

The current study estimated trends in the prevalence of daily and nondaily cigarette smoking among United States adults with any common mental health or substance use problem (MHSUP), compared to US adults without MHSUP, from 2005 to 2014.

METHODS

Data were drawn from the years 2005 to 2014 from the public use data files for the annually conducted National Survey on Drug Use and Health. Linear time trends of current, daily, and nondaily cigarette smoking among adults (age 18 years and older) with and without MHSUP were assessed using logistic regression models with continuous year as the predictor.

RESULTS

In 2014, the prevalence of current cigarette smoking among those with MHSUP was more than twice that of those without MHSUP. Nondaily cigarette smoking increased significantly from 2005 to 2014 among those with MHSUP (P = .001) in contrast to a decline in nondaily cigarette smoking among those without MHSUP (P < .01). The rate of change differed significantly (P < .001). Daily cigarette smoking declined significantly from 2005 to 2014 among those with and without MHSUP (P values < .001).

CONCLUSIONS

The prevalence of nondaily cigarette smoking is increasing among US adults with common mental health and substance use problems, while it continues to decline among those without these vulnerabilities. The disparity in prevalence of daily cigarette smoking between those with and without MHSUP remains substantial. Conclusions about how to reach the tobacco endgame may need to be reconsidered to develop targeted tobacco control public health approaches that address common MHSUP.

Bi-directional associations of electronic and combustible cigarette use onset patterns with depressive symptoms in adolescents

Whether well-documented patterns of mental health comorbidity with adolescent combustible cigarette use extend to e-cigarette use is unclear. Demonstrating associations between e-cigarette and combustible cigarette use with mental health symptomatology across adolescence may be important for promoting accurate perceptions of populations at risk for and potential consequences of tobacco product use. Adolescents (N=2460; mean age at baseline=14.1; 53.4% female; 44.1% Hispanic) who had never previously used combustible or e-cigarettes were assessed at baseline, and 6- and 12-month follow-ups in Los Angeles, CA (2013-2014). Logistic regression was used to examine associations between baseline depressive symptoms and onset of e-cigarette and cigarette single product and dual use at follow-ups. Latent growth modeling was used to examine associations between sustained use of either product (vs. non-use) and changes in depressive symptoms over 12-months. Higher baseline depressive symptoms predicted subsequent onset of cigarette (OR=1.024, 95% C.I.=1.009-1.055), e-cigarette (OR=1.015, C.I.=1.003-1.023), and dual use of both products (OR=1.021, C.I.=1.003-1.043). Sustained use of e-cigarettes over the 12-month observation (vs. non-use) was associated with a greater rate of increase in depressive symptoms over time (b=1.272, SE=0.513, p=0.01). Among those who sustained use of e-cigarettes, higher frequency of use was associated with higher depressive symptoms at the final follow-up (B=1.611, p=0.04). A bi-directional association of depressive symptoms with e-cigarette use onset across mid adolescence was observed. Further research on the causal nature, etiological underpinnings, and intervention implications of mental health and tobacco product use comorbidity is warranted.

Depression in Cardiovascular Patients in Middle Eastern Populations: A Literature Review

Cardiovascular disease (CVD) is increasing in Middle Eastern countries. Depression is associated with increased morbidity and mortality rates among cardiovascular (CV) patients. Early detection of and intervention for depression among CV patients can reduce morbidity and mortality and save health care costs. Public information on mental health care needs of Arab CV patients living in Middle East regions is scattered and limited. This literature review surveyed and summarized research studies to learn what is known about the relationship between depression and CVD in Middle Eastern populations. The information will raise awareness among health care professionals and policy makers regarding the clinical significance of depression in Arab CV patients. It might contribute to development of culturally appropriate and effective mental health care services. Multiple databases were searched and 60 articles were assessed, including studies that investigated depression in Arab CV patient populations, physiological mechanisms of depression-CVD comorbidity, and intervention strategies that affect CV risk in depressed Arab patients. We discuss the extent to which this issue has been explored in Arab populations living in Middle East regions and Arab populations living abroad. We recommend that more comprehensive and in-depth research studies be conducted with Arab cardiac patients to enable implementation of culturally appropriate and effective mental health care interventions.

Evaluation of the Nicotinic Acetylcholine Receptor-Associated Proteome at Baseline and Following Nicotine Exposure in Human and Mouse Cortex

Nicotinic acetylcholine receptors (nAChRs) support the initiation and maintenance of smoking, but the long-term changes occurring in the protein complex as a result of smoking and the nicotine in tobacco are not known. Human studies and animal models have also demonstrated that increasing cholinergic tone increases behaviors related to depression, suggesting that the nAChR-associated proteome could be altered in individuals with mood disorders. We therefore immunopurified nAChRs and associated proteins for quantitative proteomic assessment of changes in protein–protein interactions of high-affinity nAChRs containing the β2 subunit (β2*-nAChRs) from either cortex of mice treated with saline or nicotine, or postmortem human temporal cortex tissue from tobacco-exposed and nonexposed individuals, with a further comparison of diagnosed mood disorder to control subjects. We observed significant effects of nicotine exposure on the β2*-nAChR-associated proteome in human and mouse cortex, particularly in the abundance of the nAChR subunits themselves, as well as putative interacting proteins that make up core components of neuronal excitability (Na/K ATPase subunits), presynaptic neurotransmitter release (syntaxins, SNAP25, synaptotagmin), and a member of a known nAChR protein chaperone family (14-3-3ζ). These findings identify candidate-signaling proteins that could mediate changes in cholinergic signaling via nicotine or tobacco use. Further analysis of identified proteins will determine whether these interactions are essential for primary function of nAChRs at presynaptic terminals. The identification of differences in the nAChR-associated proteome and downstream signaling in subjects with various mood disorders may also identify novel etiological mechanisms and reveal new treatment targets.

Acute administration of nicotine into the higher order auditory Te2 cortex specifically decreases the fear-related charge of remote emotional memories

Nicotine elicits several behavioural effects on mood as well as on stress and anxiety processes. Recently, it was found that the higher order components of the sensory cortex, such as the secondary auditory cortex Te2, are essential for the long-term storage of remote fear memories. Therefore, in the present study, we examined the effects of acute nicotine injection into the higher order auditory cortex Te2, on the remote emotional memories of either threat or incentive experiences in rats. We found that intra-Te2 nicotine injection decreased the fear-evoked responses to a tone previously paired with footshock. This effect was cue- and dose-specific and was not due to any interference with auditory stimuli processing, innate anxiety and fear processes, or with motor responses. Nicotine acts acutely in the presence of threat stimuli but it did not determine the permanent degradation of the fear-memory trace, since memories tested one week after nicotine injection were unaffected. Remarkably, nicotine did not affect the memory of a similar tone that was paired to incentive stimuli. We conclude from our results that nicotine, when acting acutely in the auditory cortex, relieves the fear charge embedded by learned stimuli.

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Nicotine reliefs fear memories.

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Nicotine acts on long-term memories.

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Nicotine modulates memory in auditory cortex.

Associations of cannabis and cigarette use with depression and anxiety at age 18: findings from the Avon Longitudinal Study of Parents and Children

Introduction

Substance use is associated with common mental health disorders, but the causal effect of specific substances is uncertain. We investigate whether adolescent cannabis and cigarette use is associated with incident depression and anxiety, while attempting to account for confounding and reverse causation.

Methods

We used data from ALSPAC, a UK birth cohort study, to investigate associations between cannabis or cigarettes (measured at age 16) and depression or anxiety (measured at age 18), before and after adjustment for pre-birth, childhood and adolescent confounders. Our imputed sample size was 4561 participants.

Results

Both cannabis (unadjusted OR 1.50, 95% CI 1.26, 1.80) and cigarette use (OR 1.37, 95% CI 1.16, 1.61) increased the odds of developing depression. Adjustment for pre-birth and childhood confounders partly attenuated these relationships though strong evidence of association persisted for cannabis use. There was weak evidence of association for cannabis (fully adjusted OR 1.30, 95% CI 0.98, 1.72) and insufficient evidence for association for cigarette use (fully adjusted OR = 0.97, 95% CI 0.75, 1.24) after mutually adjusting for each other, or for alcohol or other substance use. Neither cannabis nor cigarette use were associated with anxiety after adjustment for pre-birth and childhood confounders.

Conclusions

Whilst evidence of association between cannabis use and depression persisted after adjusting for pre-term and childhood confounders, our results highlight the difficulties in trying to estimate and interpret independent effects of cannabis and tobacco on psychopathology. Complementary methods are required to robustly examine effects of cannabis and tobacco on psychopathology.

Mood and anxiety regulation by nicotinic acetylcholine receptors: A potential pathway to modulate aggression and related behavioral states

The co-morbidity between smoking and mood disorders is striking. Preclinical and clinical studies of nicotinic effects on mood, anxiety, aggression, and related behaviors, such as irritability and agitation, suggest that smokers may use the nicotine in tobacco products as an attempt to self-medicate symptoms of affective disorders. The role of nicotinic acetylcholine receptors (nAChRs) in circuits regulating mood and anxiety is beginning to be elucidated in animal models, but the mechanisms underlying the effects of nicotine on aggression-related behavioral states (ARBS) are still not understood. Clinical trials of nicotine or nicotinic medications for neurological and psychiatric disorders have often found effects of nicotinic medications on ARBS, but few trials have studied these outcomes systematically. Similarly, the increase in ARBS resulting from smoking cessation can be resolved by nicotinic agents, but the effects of nicotinic medications on these types of mental states and behaviors in non-smokers are less well understood. Here we review the literature on the role of nAChRs in regulating mood and anxiety, and subsequently on the closely related construct of ARBS. We suggest avenues for future study to identify how nAChRs and nicotinic agents may play a role in these clinically important areas. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.

EPA Guidance on Tobacco Dependence and Strategies for Smoking Cessation in People with Mental Illness

Tobacco dependence is the most common substance use disorder in adults with mental illness. The prevalence rates for tobacco dependence are two to four times higher in these patients than in the general population. Smoking has a strong, negative influence on the life expectancy and quality of life of mental health patients, and remains the leading preventable cause of death in this group. Despite these statistics, in some countries smokers with mental illness are disadvantaged in receiving intervention and support for their tobacco dependence, which is often overlooked or even tolerated. This statement from the European Psychiatric Association (EPA) systematically reviews the current evidence on tobacco dependence and withdrawal in patients with mental illness and their treatment. It provides seven recommendations for the core components of diagnostics and treatment in this patient group. These recommendations concern: (1) the recording process, (2) the timing of the intervention, (3) counselling specificities, (4) proposed treatments, (5) frequency of contact after stopping, (6) follow-up visits and (7) relapse prevention. They aim to help clinicians improve the care, health and well-being of patients suffering from mental illness.

Cigarette smoking and completed suicide: results from 3 prospective cohorts of American adults

BACKGROUND

Prior reports have indicated a potential dose-response relationship between smoking and suicide. However, this relationship is controversial.

METHODS

This study evaluated the association between smoking and risk of death from suicide in three large-scale cohorts of U.S. men and women (n=253,033). Suicides were identified from death certificates among 43,816 men enrolled in the Health Professionals Follow-up Study (HPFS) between 1986 and 2008, 116,566 women in the Nurses' Health Study (NHS) between 1976 and 2008, and 92,651 women in the NHS II between 1989 and 2007. Information on smoking was obtained at baseline and updated every 2 years. Relative risks (RRs) of suicide were estimated using Cox proportional hazards regression models. Cohort specific RRs were pooled using random-effects models. Suicide deaths were determined by physician review of death certificates.

RESULTS

A total of 457 deaths from suicide were documented. Compared to never smokers, the pooled multivariate RR (95% confidence interval [CI]) of suicide was 1.15 (0.91-1.45) for former smokers and 2.69 (2.11-3.42) for current smokers. A nonmonotonic dose-response relationship was noted between the number of cigarettes smoked per day (CPD) and suicide risk (P trend<0.001). Compared to never smokers, the pooled multivariate RR (95% CI) was 2.59 (1.77-3.79) for those with 1-14 CPD, 2.03 (1.39-2.94) for those with 15-24 CPD, and 4.13 (2.96-5.78) for those with ≥ 25 CPD.

LIMITATIONS

Smoking was self-reported and had some degree of measurement error. Participants were not a representative sample of the U.S. population.

CONCLUSIONS

Results from three large cohorts suggest a nonmonotonic dose-response association between smoking and suicide risk.

Using Mendelian randomisation to infer causality in depression and anxiety research

Depression and anxiety co-occur with substance use and abuse at a high rate. Ascertaining whether substance use plays a causal role in depression and anxiety is difficult or impossible with conventional observational epidemiology. Mendelian randomisation uses genetic variants as a proxy for environmental exposures, such as substance use, which can address problems of reverse causation and residual confounding, providing stronger evidence about causality. Genetic variants can be used instead of directly measuring exposure levels, in order to gain an unbiased estimate of the effect of various exposures on depression and anxiety. The suitability of the genetic variant as a proxy can be ascertained by confirming that there is no relationship between variant and outcome in those who do not use the substance. At present, there are suitable instruments for tobacco use, so we use that as a case study. Proof-of-principle Mendelian randomisation studies using these variants have found evidence for a causal effect of smoking on body mass index. Two studies have investigated tobacco and depression using this method, but neither found strong evidence that smoking causes depression or anxiety; evidence is more consistent with a self-medication hypothesis. Mendelian randomisation represents a technique that can aid understanding of exposures that may or may not be causally related to depression and anxiety. As more suitable instruments emerge (including the use of allelic risk scores rather than individual single nucleotide polymorphisms), the effect of other substances can be investigated. Linkage disequilibrium, pleiotropy, and population stratification, which can distort Mendelian randomisation studies, are also discussed.

Smoking, mental illness and socioeconomic disadvantage: analysis of the Australian National Survey of Mental Health and Wellbeing

BACKGROUND

High rates of smoking and lower rates of smoking cessation are known to be associated with common mental disorders such as anxiety and depression, and with individual and community measures of socioeconomic status. It is not known to what extent mental illness and socioeconomic status might be jointly associated with smoking behaviour. We set out to examine the relationship between mental illness, measures of socioeconomic disadvantage and both current smoking and smoking cessation rates.

METHODS

We used data from the 2007 Australian National Survey of Mental Health and Wellbeing to examine the relationship between mental illness, socioeconomic status and both current smoking and smoking cessation. We used cross-classified tables and logistic regression to examine the relationship between psychosocial and sociodemographic predictors and current smoking. We also used proportional hazards regression to examine the relationship between the factors and smoking cessation.

RESULTS

Both mental illness and socioeconomic status were independently associated with current smoking and with lower likelihood of smoking cessation, with gradients in smoking by mental health status being observed within levels of socioeconomic indicators and vice versa. Having a mental illness in the past 12 months was the most prevalent factor strongly associated with smoking, affecting 20.0% of the population, associated with increased current smoking (OR 2.43; 95% CI: 1.97-3.01) and reduced likelihood of smoking cessation (HR: 0.77; 95% CI: 0.65-0.91).

CONCLUSIONS

The association between mental illness and smoking is not explained by the association between mental illness and socioeconomic status. There are strong socioeconomic and psychosocial gradients in both current smoking and smoking cessation. Incorporating knowledge of the other adverse factors in smokers' lives may increase the penetration of tobacco control interventions in population groups that have historically benefitted less from these activities.

Association of mental distress with smoking status in the community: Results from the Gutenberg Health Study

BACKGROUND

Exposition to tobacco smoke is among the major modifiable risk factors in the general population. There is strong evidence for a close association between smoking exposure and mental disorders.

METHODS

Cross-sectional associations of different conditions of smoking status (former, current, and second hand smoking (SHS)) with indicators of mental distress were analyzed in a sample of N=5000 participants (aged 35-74 years) of the population-based survey "Gutenberg Health Study".

RESULTS

In the general population clinically significant depression (OR 1.59, 95%CI 1.17-2.17) and a previous diagnosis of depression (OR 1.50, 95%CI 1.16-1.94) were associated with current smoking. Each cigarette per day was associated with a 3% increase for the likelihood of clinically significant depression. We did not find a decreased prevalence for current first and second hand exposure in persons with established cardiovascular or lung disease. In this subgroup mental distress was strongly associated with SHS at home.

LIMITATIONS

Main limitations of the study pertain to the reliance on self-report of distress and smoking status and the cross-sectional nature of the data.

CONCLUSIONS

Despite public health efforts, smoke exposure is still alarmingly high in the general population, especially in persons with mental distress and with established cardiovascular or lung disease. In the management of persons with chronic cardiovascular and lung disease, enquiry of the medical history should include exposure to SHS at home and offer special counseling.

Examining antidepressant drug response by smoking status: why is it important and how often is it done?

Despite an increasingly recognized relationship between depression and smoking, little is known about the degree to which treatment studies for depression consider the impact of smoking on outcomes. The aim of this study is to examine the extent to which smoking is considered in current antidepressant treatment research. We conducted a MEDLINE search of recent randomized clinical trials of pharmacotherapy for depression published between 1 January and 31 December 2007, and a search of current pharmacological intervention studies for depression using www.ClinicalTrials.gov. Only 5% of the 107 pharmacological trials for depression published in 2007 reported the smoking status of their samples. Two studies (1.9%) controlled for smoking in the analyses and no studies analyzed outcomes by smoking status. Excluding the eight studies of combined treatment for depression and nicotine dependence, no other study on www.ClinicalTrials.gov (total n = 920) reported an intention to analyze outcomes by smoking status. Emerging data link smoking and depression, however, little attention has been directed toward the effects of smoking on antidepressant treatment outcomes. Conducting research to understand how nicotine and smoking affect responsiveness to antidepressants would advance our understanding of the neurobiology of depression and the development of new and targeted treatments.

Discovery of 1-[2-(2,4-dimethylphenylsulfanyl)phenyl]piperazine (Lu AA21004): a novel multimodal compound for the treatment of major depressive disorder

The synthesis and structure-activity relationship of a novel series of compounds with combined effects on 5-HT(3A) and 5-HT(1A) receptors and on the serotonin (5-HT) transporter (SERT) are described. Compound 5m (Lu AA21004) was the lead compound, displaying high affinity for recombinant human 5-HT(1A) (K(i) = 15 nM), 5-HT(1B) (K(i) = 33 nM), 5-HT(3A) (K(i) = 3.7 nM), 5-HT(7) (K(i) = 19 nM), and noradrenergic β(1) (K(i) = 46 nM) receptors, and SERT (K(i) = 1.6 nM). Compound 5m displayed antagonistic properties at 5-HT(3A) and 5-HT(7) receptors, partial agonist properties at 5-HT(1B) receptors, agonistic properties at 5-HT(1A) receptors, and potent inhibition of SERT. In conscious rats, 5m significantly increased extracellular 5-HT levels in the brain after acute and 3 days of treatment. Following the 3-day treatment (5 or 10 (mg/kg)/day) SERT occupancies were only 43% and 57%, respectively. These characteristics indicate that 5m is a novel multimodal serotonergic compound, and 5m is currently in clinical development for major depressive disorder.

Nicotine increases neural response to unpleasant stimuli and anxiety in non-smokers

Studies in smokers suggest that nicotine might exert anxiolytic, stress-dampening and mood-enhancing effects and beneficially influences neural processing of affective information. Regarding non-smokers, results are inconsistent, and no data exist on the effect of nicotine on neural emotion processing. We applied functional magnetic resonance imaging (fMRI) to assess the influence of nicotine on brain activation during processing of emotional stimuli in 31 non-smokers with a maximum lifetime cigarette consumption of 20 cigarettes. Participants were subjected to two fMRI scans with event-related presentations of images taken from the International Affective Picture System, receiving nicotine (2 mg) and placebo gums in a double-blinded, randomized cross-over design. Furthermore, subjective affect was assessed. Nicotine increased brain activity in response to unpleasant stimuli in the amygdala, anterior cingulate cortex (ACC) and basal ganglia, whereas processing of pleasant stimuli was not altered. Psychophysiological interaction (PPI) analyses revealed that nicotine increased connectivity between the amygdala and the perigenual ACC (pACC) during processing of unpleasant stimuli and decreased connectivity between those structures during processing of pleasant stimuli. Participants reported higher state anxiety under nicotine than placebo. A single dose of nicotine acted as a stressor in non-smokers, leading to increased anxiety and neural activation elicited by unpleasant stimuli as well as altered connectivity within the amygdala-pACC circuit. Besides the possibility that reactions to nicotine may differ between non-smokers and smokers due to tolerance and neuroadaptive processes that occur during prolonged nicotine use, a priori differences in smokers and non-smokers might potentially explain diverse effects of nicotine on affect and emotional reactivity.

Smoking concordance in lung and colorectal cancer patient-caregiver dyads and quality of life

BACKGROUND

Distress may be heightened among members of cancer patient-caregiver dyads that are mismatched on smoking status (either the patient or caregiver smokes, but the other does not), negatively affecting quality of life (QoL). The purpose of this study was to examine associations between patient-caregiver smoking concordance, caregiver psychological adjustment, and caregiver and patient mental and physical QoL.

METHODS

Lung and colorectal patient-caregiver dyads (N = 742) were identified from the Cancer Care Outcomes Research and Surveillance (CanCORS) and CanCORS Caregiver studies. The majority of the cancer patients were male (67.0%) with local (45.6%) or regional (12.9%) disease. The majority of the informal caregivers were females (78.6%), under 65 years of age (69.6%), and often spouses (57.8%) of the patients.

RESULTS

Lung and colorectal cancer caregivers, who were members of dyads where one or both members continued to smoke, reported worse mental health QoL than nonsmoking dyads. For colorectal cancer patients, continuing to smoke when the caregiver did not was associated with worse mental health QoL compared with nonsmoking dyads. Dyad smoking was less strongly associated with physical QoL for both caregivers and patients.

CONCLUSION

Results highlight the importance of assessing smoking in both cancer patients and their caregivers and referring families to appropriate psychosocial and smoking cessation services.

IMPACT

This is the first study to show associations between cancer patient-caregiver smoking status and QoL for both dyad members. Future studies will need to confirm these associations longitudinally and investigate potential mechanisms linking dyad smoking and QoL.

Depression and the subsequent risk of Parkinson's disease in the NIH-AARP Diet and Health Study

We conducted a case-control study to examine the association between depression and Parkinson's disease (PD). Participants included 992 PD cases diagnosed after 2,000 and 279,958 individuals without PD from the NIH-AARP Diet and Health Study follow-up survey. Physician-diagnosed depression and PD were self-reported with information on the year of diagnosis in the following categories: before 1985, 1985-1994, 1995-1999, and 2000-present. Only PD cases diagnosed after 2000 were included in the analysis. Odds ratios (ORs) and 95% confidence intervals (CIs) were derived from logistic regression models, adjusted for age, gender, educational level, marital status, smoking, and coffee drinking. Individuals with depression diagnosed after 2000 were more likely to report a concurrent diagnosis of PD than those without depression (OR = 4.7, 95% CI = 3.9, 5.7). Depression diagnosed before 2000 was also associated with higher odds of PD diagnosed after 2000 (OR = 2.0, 95% CI = 1.6, 2.4). This association was stronger for depression diagnosed in 1995-1999 (OR = 2.7, 95% CI = 2.0, 3.6), but was also noted for depression diagnosed in 1985-1994 (OR = 1.6, 95% CI = 1.1, 2.3) or even before 1985 (OR = 1.7, 95% CI = 1.3, 2.3). This association was not modified by other factors and persisted in an analysis excluding participants who reported poor health status. The results suggest that depression may either be a very early symptom of PD or share common etiological factors with PD.

Depression in patients with heart disease: the case for more trials

Depression is common among patients with heart disease. It is an important comorbidity, both because of its well-known effect on the quality of life and also because it has a significant impact on the ability of patients with heart disease to engage in healthy behaviors and to avoid unhealthy ones. In addition, depression is associated with increased morbidity and mortality in those with established cardiovascular disease. However, no study has demonstrated that treatment of depression improves cardiac outcomes in patients with heart disease. Some have argued that additional trials are not necessary, and that the importance of depression argues for increased recognition and treatment even if it cannot be demonstrated that this improves morbidity and mortality. This article makes the case for more trials in this area, highlighting the importance of using the results of prior trials to generate hypotheses and provide directions for future studies in this area and noting the effect that demonstrating improved survival might have on clinical practice.

Human dopamine receptor D2/D3 availability predicts amygdala reactivity to unpleasant stimuli

Dopamine (DA) modulates the response of the amygdala. However, the relation between dopaminergic neurotransmission in striatal and extrastriatal brain regions and amygdala reactivity to affective stimuli has not yet been established. To address this issue, we measured DA D2/D3 receptor (DRD2/3) availability in twenty-eight healthy men (nicotine-dependent smokers and never-smokers) using positron emission tomography with [18F]fallypride. In the same group of participants, amygdala response to unpleasant visual stimuli was determined using blood oxygen level-dependent (BOLD) functional magnetic resonance imaging. The effects of DRD2/3 availability in emotion-related brain regions and nicotine dependence on amygdala response to unpleasant stimuli were examined by multiple regression analysis. We observed enhanced prefrontal DRD2/3 availability in those individuals with higher amygdala response to unpleasant stimuli. As compared to never-smokers, smokers showed an attenuated amygdala BOLD response to unpleasant stimuli. Thus, individuals with high prefrontal DRD2/3 availability may be more responsive toward aversive and stressful information. Through this mechanism, dopaminergic neurotransmission might influence vulnerability for affective and anxiety disorders. Neuronal reactivity to unpleasant stimuli seems to be reduced by smoking. This observation could explain increased smoking rates in individuals with mental disorders.

Smoking and mental illness: results from population surveys in Australia and the United States

BACKGROUND

Smoking has been associated with a range of mental disorders including schizophrenia, anxiety disorders and depression. People with mental illness have high rates of morbidity and mortality from smoking related illnesses such as cardiovascular disease, respiratory diseases and cancer. As many people who meet diagnostic criteria for mental disorders do not seek treatment for these conditions, we sought to investigate the relationship between mental illness and smoking in recent population-wide surveys.

METHODS

Survey data from the US National Comorbidity Survey-Replication conducted in 2001-2003, the 2007 Australian Survey of Mental Health and Wellbeing, and the 2007 US National Health Interview Survey were used to investigate the relationship between current smoking, ICD-10 mental disorders and non-specific psychological distress. Population weighted estimates of smoking rates by disorder, and mental disorder rates by smoking status were calculated.

RESULTS

In both the US and Australia, adults who met ICD-10 criteria for mental disorders in the 12 months prior to the survey smoked at almost twice the rate of adults without mental disorders. While approximately 20% of the adult population had 12-month mental disorders, among adult smokers approximately one-third had a 12-month mental disorder--31.7% in the US (95% CI: 29.5%-33.8%) and 32.4% in Australia (95% CI: 29.5%-35.3%). Female smokers had higher rates of mental disorders than male smokers, and younger smokers had considerably higher rates than older smokers. The majority of mentally ill smokers were not in contact with mental health services, but their rate of smoking was not different from that of mentally ill smokers who had accessed services for their mental health problem. Smokers with high levels of psychological distress smoked a higher average number of cigarettes per day.

CONCLUSION

Mental illness is associated with both higher rates of smoking and higher levels of smoking among smokers. Further, a significant proportion of smokers have mental illness. Strategies that address smoking in mental illness, and mental illness among smokers would seem to be important directions for tobacco control. As the majority of smokers with mental illness are not in contact with mental health services for their condition, strategies to address mental illness should be included as part of population health-based mental health and tobacco control efforts.

Smoking and mental illness: results from population surveys in Australia and the United States

BACKGROUND

Smoking has been associated with a range of mental disorders including schizophrenia, anxiety disorders and depression. People with mental illness have high rates of morbidity and mortality from smoking related illnesses such as cardiovascular disease, respiratory diseases and cancer. As many people who meet diagnostic criteria for mental disorders do not seek treatment for these conditions, we sought to investigate the relationship between mental illness and smoking in recent population-wide surveys.

METHODS

Survey data from the US National Comorbidity Survey-Replication conducted in 2001-2003, the 2007 Australian Survey of Mental Health and Wellbeing, and the 2007 US National Health Interview Survey were used to investigate the relationship between current smoking, ICD-10 mental disorders and non-specific psychological distress. Population weighted estimates of smoking rates by disorder, and mental disorder rates by smoking status were calculated.

RESULTS

In both the US and Australia, adults who met ICD-10 criteria for mental disorders in the 12 months prior to the survey smoked at almost twice the rate of adults without mental disorders. While approximately 20% of the adult population had 12-month mental disorders, among adult smokers approximately one-third had a 12-month mental disorder--31.7% in the US (95% CI: 29.5%-33.8%) and 32.4% in Australia (95% CI: 29.5%-35.3%). Female smokers had higher rates of mental disorders than male smokers, and younger smokers had considerably higher rates than older smokers. The majority of mentally ill smokers were not in contact with mental health services, but their rate of smoking was not different from that of mentally ill smokers who had accessed services for their mental health problem. Smokers with high levels of psychological distress smoked a higher average number of cigarettes per day.

CONCLUSION

Mental illness is associated with both higher rates of smoking and higher levels of smoking among smokers. Further, a significant proportion of smokers have mental illness. Strategies that address smoking in mental illness, and mental illness among smokers would seem to be important directions for tobacco control. As the majority of smokers with mental illness are not in contact with mental health services for their condition, strategies to address mental illness should be included as part of population health-based mental health and tobacco control efforts.

Varenicline augmentation in depressed smokers: an 8-week, open-label study

OBJECTIVE

To assess possible antidepressant effects of varenicline augmentation in outpatients with treatment-resistant depressive disorders and nicotine dependence.

BACKGROUND

Varenicline is a nicotinic acetylcholine receptor alpha4beta2 partial agonist and alpha7 full agonist approved for smoking cessation. Studies of similar compounds have suggested evidence of antidepressant effects.

METHOD

Eighteen patients (aged 18 to 65 years) were recruited from a general psychiatric outpatient clinic. Inclusion criteria were (1) primary Axis I depressive disorder (DSM-IV-TR criteria), (2) a stable antidepressant or mood stabilizer regimen, (3) persistent depressive symptoms despite adequate treatment, and (4) current cigarette smoking with nicotine dependence. Patients received varenicline (started at 0.5 mg daily and titrated to 1 mg twice daily) in addition to stable doses of their regular psychotropic medications. Depression symptoms, side effects, clinical global impressions, anhedonia, daily cigarette consumption, and vital signs were assessed every 2 weeks for 8 weeks. Baseline and endpoint ratings were compared, and the relationship between mood improvement and smoking cessation was examined. The primary outcome variable was mean change score in depressive symptoms as assessed by the 16-item Quick Inventory of Depressive Symptomatology-Self-Report. The study was conducted between September 2007 and March 2008.

RESULTS

Fourteen patients (78%) completed the study; 4 discontinued due to side effects, including gastrointestinal effects (n = 3) and worsened mood/irritability (n = 1). Patients demonstrated significant improvement in depression at end point (p < .001), with significant improvement as early as week 2. Eight patients (44%) met criteria for categorical response, and 6 (33%) reached remission criteria; the overall effect size was large. All patients were interested in smoking cessation: 8 (44%) achieved abstinence and 9 (50%) had some reduction in smoking. Improvement in depressive symptoms was correlated with smoking cessation. There was no evidence of treatment-emergent suicidality.

CONCLUSION

Open-label varenicline augmentation was associated with significant improvement in mood in a small sample of outpatient smokers with persistent depressive symptoms. Larger, double-blind studies are needed to investigate potential antidepressant effects of varenicline augmentation.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00525837.

Cognitive and antismoking effects of varenicline in patients with schizophrenia or schizoaffective disorder

OBJECTIVE

Varenicline has been shown to be an effective anti-smoking treatment in smokers without identified psychiatric illness, and the drug's pharmacology suggests possibilities of pro-cognitive effects. However, recent reports suggest varenicline may have the potential for important psychiatric side-effects in some people. We present the first prospective quantitative data on the effects of varenicline on cognitive function, cigarette smoking, and psychopathology in a small sample of schizophrenic patients.

METHOD

Fourteen schizophrenic smokers were enrolled in an open-label study of varenicline with a pre-post design. Measures of cognitive function (RBANS, Virtual Water-Maze Task), cigarette smoking (cotinine levels, CO levels, self-reported smoking and smoking urges), and psychopathology (PANSS) were evaluated prior to and during treatment with varenicline. Data on psychopathology changes among schizophrenic smokers in another drug study, in which patients were not receiving varenicline, were used for comparison.

RESULTS

12 patients completed the study, and 2 patients terminated in the first two weeks of active varenicline because of complaints of nausea or shaking. Varenicline produced significant improvements in some cognitive test scores, primarily associated with verbal learning and memory, but not in scores on visual-spatial learning or memory, or attention. Varenicline significantly decreased all indices of smoking, but did not produce complete smoking abstinence in most patients. During treatment with varenicline there were no significant increases in psychopathology scores and no patient developed signs of clinical depression or suicidal ideation.

CONCLUSIONS

Our small prospective study suggests that treatment with varenicline appears to have some beneficial cognitive effects which need to be confirmed in larger studies with additional neuropsychological tests. Varenicline appears to have some anti-smoking efficacy in schizophrenia but longer studies are needed to determine whether it will produce rates of smoking abstinence similar to those found in control smokers. Treatment with varenicline may not increase psychopathology or depression in most patients with schizophrenia, but we cannot accurately estimate the absolute risk of a potentially rare side-effect from this small sample.

Progesterone modulation of alpha5 nAChR subunits influences anxiety-related behavior during estrus cycle

Smokers often report an anxiolytic effect of cigarettes. In addition, stress-related disorders such as anxiety, post-traumatic stress syndrome and depression are often associated with chronic nicotine use. To study the role of the alpha5 nicotinic acetylcholine receptor subunit in anxiety-related responses, control and alpha5 subunit null mice (alpha5(-/-)) were subjected to the open field activity (OFA), light-dark box (LDB) and elevated plus maze (EPM) tests. In the OFA and LDB, alpha5(-/-) behaved like wild-type controls. In the EPM, female alpha5(-/-) mice displayed an anxiolytic-like phenotype, while male alpha5(-/-) mice were undistinguishable from littermate controls. We studied the hypothalamus-pituitary-adrenal axis by measuring plasma corticosterone and hypothalamic corticotropin-releasing factor. Consistent with an anxiolytic-like phenotype, female alpha5(-/-) mice displayed lower basal corticosterone levels. To test whether gonadal steroids regulate the expression of alpha5, we treated cultured NTera 2 cells with progesterone and found that alpha5 protein levels were upregulated. In addition, brain levels of alpha5 mRNA increased upon progesterone injection into ovariectomized wild-type females. Finally, we tested anxiety levels in the EPM during the estrous cycle. The estrus phase (when progesterone levels are low) is anxiolytic-like in wild-type mice, but no cycle-dependent fluctuations in anxiety levels were found in alpha5(-/-) females. Thus, alpha5-containing neuronal nicotinic acetylcholine receptors may be mediators of anxiogenic responses, and progesterone-dependent modulation of alpha5 expression may contribute to fluctuations in anxiety levels during the ovarian cycle.

Differential pharmacologies of mecamylamine enantiomers: positive allosteric modulation and noncompetitive inhibition

(+/-)-Mecamylamine is a racemic mixture of a widely used brain-permeant noncompetitive inhibitor of muscle-type and neuronal nicotinic receptors (NNRs). The present studies evaluated whether the stereoisomers of this drug show different profiles for inhibition of the high-sensitivity (HS) and low-sensitivity (LS) isoforms of the human alpha4beta2 NNR subtype expressed in subclonal human epithelial 1 cells. We found that at low concentrations (micromolar range), TC-5214 [S-(+)-mecamylamine] was more effective than TC-5213 [R-(-)-mecamylamine] in inhibiting the LS alpha4beta2 NNRs. In addition, we demonstrated that TC-5214 potentiated and TC-5213 inhibited agonist-induced activation of HS alpha4beta2 NNRs. The stereoselectivity of mecamylamine enantiomers at HS and LS alpha4beta2 receptors demonstrates that TC-5214 is the preferred stereoisomer for selective activation of HS, whereas it is more effective in suppressing LS receptor function. This feature could be relevant to therapeutic applications where such a selective mechanism of action is required.

Behavioural and pharmacological mechanisms of bupropion's anti-smoking effects: recent preclinical and clinical insights

Ongoing studies continue to explore the behavioural and pharmacological effects of bupropion in smoking cessation studies and animal models of nicotine dependence. In the present review, the components of nicotine dependence that form the most likely targets of bupropion are identified within the context of an expanding preclinical and clinical literature regarding the anti-addictive properties of bupropion. Second, preclinical and clinical data that implicate specific pharmacological modes of action of bupropion in mediating the anti-smoking effects of the compound are discussed. Third, it is suggested that the unique mixed pharmacological profile of bupropion provides (1) attenuation of the multiple negative consequences of withdrawal via blockade of dopamine and noradrenaline reuptake; (2) replacement of the reward-facilitating and subjective effects of nicotine via blockade of dopaminergic reuptake; (3) attenuation of the rewarding effects of acute nicotine by nicotinic acetylcholine receptor blockade. The importance of species differences in bupropion metabolism in the interpretation of preclinical studies is highlighted. Finally, future studies are suggested to address identified gaps in the knowledge: most importantly, to provide stronger evidence for the role of noradrenaline reuptake inhibition in bupropion-induced attenuation of nicotine withdrawal. Future studies aimed at providing more evidence for the three-fold nature of the anti-smoking effects of bupropion are also suggested, along with the possibility of utilizing adjunct therapies to improve smoking cessation rates.

Subtypes of nicotinic acetylcholine receptors in nicotine reward, dependence, and withdrawal: evidence from genetically modified mice

Neuronal nicotinic acetylcholine receptors (nAChRs) can regulate the activity of many neurotransmitter pathways throughout the central nervous system and are considered to be important modulators of cognition and emotion. nAChRs are also the primary site of action in the brain for nicotine, the major addictive component of tobacco smoke. nAChRs consist of five membrane-spanning subunits (alpha and beta isoforms) that can associate in various combinations to form functional nAChR ion channels. Owing to a dearth of nAChR subtype-selective ligands, the precise subunit composition of the nAChRs that regulate the rewarding effects of nicotine and the development of nicotine dependence are unknown. The advent of mice with genetic nAChR subunit modifications, however, has provided a useful experimental approach to assess the contribution of individual subunits in vivo. Here, we review data generated from nAChR subunit knockout and genetically modified mice supporting a role for discrete nAChR subunits in nicotine reinforcement and dependence processes. Importantly, the rates of tobacco dependence are far higher in patients suffering from comorbid psychiatric illnesses compared with the general population, which may at least partly reflect disease-associated alterations in nAChR signaling. An understanding of the role of nAChRs in psychiatric disorders associated with high rates of tobacco addiction, therefore, may reveal novel insights into mechanisms of nicotine dependence. Thus, we also briefly review data generated from genetically modified mice to support a role for discrete nAChR subunits in anxiety disorders, depression, and schizophrenia.

Comorbidity of depression with chronic diseases: a population-based study in Aleppo, Syria

OBJECTIVE

To assess the comorbidity and correlates of depression in chronic diseases in the community in Aleppo, Syria. This has never been previously investigated in an Arab country.

METHOD

We conducted a cross-sectional, population-based study in Aleppo on adults aged 18-65 (N = 2038). We collected data utilizing a structured interview questionnaire. Socio-demographics, general health information, and self-report of physician-diagnosed depression and chronic diseases active in the past year were obtained. We used logistic regression to estimate the odds of depression in chronic diseases and socio-demographic correlates of depression comorbid with chronic diseases.

RESULTS

Mean age (SD) was 35.3 (12.1) years, 55% were female. In women, predictors of depression were heart disease (OR = 3.95, 95% CI: 1.50-10.40), hypertension (OR = 2.92, 95% CI: 1.53-5.55), and kidney disease (OR = 2.96, 95% CI: 1.64-5.32). Depression comorbidity with any chronic disease decreased in higher socio-economic status (middle vs. low: OR = 0.28, 95% CI: 0.12-0.65; high vs. low: OR = 0.20, 95% CI: 0.05-0.81). In men, predictors of depression were rheumatism (OR = 7.10, 95% CI: 2.58-19.60) and respiratory disease (OR = 3.77, 95% CI: 1.23-11.60). Depression comorbidity decreased in residence in formal zones (OR = 0.22, 95% CI: 0.06-0.80).

CONCLUSION

Depression is associated with many chronic diseases in the community in Aleppo, a finding consistent with reports from other cultures. Potential gender-related risk factors were identified. Findings inform public mental health planning and support the delivery of depression treatment in primary care settings.

Características psicológicas associadas ao comportamento de fumar tabaco

Este artigo apresenta uma revisão da literatura sobre a psicologia do tabagismo, destacando características de personalidade do fumante como um dos obstáculos à cessação do tabagismo. Descreve-se a relação entre tabagismo e personalidade e, a seguir, a relação do tabagismo com os principais transtornos psiquiátricos. Estudos revelam que os fumantes tendem a ser mais extrovertidos, ansiosos, tensos, impulsivos e com mais traços de neuroticismo e psicoticismo, em comparação a ex-fumantes e não fumantes. A literatura revela, ainda, forte associação entre tabagismo e transtornos mentais, como esquizofrenia e depressão, entre outros. A compreensão dos fatores de natureza psicológica associados ao consumo e à dependência pode contribuir para a elaboração e aperfeiçoamento de estratégias terapêuticas para o tratamento da dependência e/ou programas de cunho educativo/preventivo.

Was John Reid right? Smoking, class, and pleasure: a population-based cohort study in England

OBJECTIVES

To assess whether there is a relationship between smoking and levels of overall quality of life, or with the pleasure domain of quality of life, in lower socio-economic groups (SES).

STUDY DESIGN

Cohort study involving 9176 individuals aged 50 years and over who participated in the Health Survey for England and were followed up in Wave 1 of the English Longitudinal Study of Ageing in 2002.

METHODS

We classified smokers as never-smokers, ex-smokers and current smokers, and used household wealth as a marker for socio-economic position. Pleasure was assessed using the pleasure subscale of the CASP-19 instrument, a 19-point measure of quality of life that covers four theoretical domains: control, autonomy, self-realization and pleasure.

RESULTS

We found that the odds ratio for experiencing lower than median levels of pleasure for smokers with low SES was 1.42 (95% CI 1.16-1.74), and for all smokers was 1.33 (95% CI 1.17-1.51). The same pattern of associations was found when the outcome was total CASP-19 score or positive GHQ-12 score.

CONCLUSIONS

We found no evidence to support a claim that smoking is associated with heightened levels of pleasure, either in people with low SES or in the general population. In fact, our results suggest the opposite: that smoking is associated with lower levels of pleasure and poorer overall quality of life. Policy decisions on smoking should consider its potentially harmful effect on quality of life and pleasure as well as on other aspects of health.

Pharmakologische Rückfallprävention bei Alkohol- und Tabakabhängigkeit

A better understanding of the neurobiological substrates of alcohol and tobacco dependence has been accompanied by the increasing role of pharmacological relapse prevention. In alcohol dependence, substances which are able to block or ameliorate alcohol craving improve the maintenance of abstinence in combination with psychosocial treatment. In particular, the N-methyl-D-aspartate receptor antagonist acamprosate and the opiate receptor antagonist naltrexone have been shown to be effective in numerous trials. Administration starts immediately after detoxification and should last for 12 months. This treatment, however, is not a replacement for the psychosocial treatment of the alcohol dependence. Compared with placebo treatment, approximately twice as many patients remain abstinent under acamprosate 1 year after the end of treatment. The most widely studied and used pharmacotherapy for the treatment of tobacco dependence is nicotine containing medications. Nicotine replacement therapies (patch, gum, tablet, inhaler) have been shown to reduce tobacco craving and enhance abstinence. The only non-nicotine medication that has been approved in Germany is the antidepressant bupropion. Current studies identify particularly suitable subgroups of patients responding to more individualized pharmacological relapse prevention. A specific application of these substances will optimise the outcome for alcohol and tobacco dependent patients.

The nicotinic antagonist mecamylamine has antidepressant-like effects in wild-type but not beta2- or alpha7-nicotinic acetylcholine receptor subunit knockout mice

RATIONALE

Increases in cholinergic transmission are linked to depression in human subjects and animal models. We therefore examined the effect of decreasing nicotinic acetylcholine receptor (nAChR) activity in tests of antidepressant efficacy using C57BL/6J mice.

OBJECTIVES

We determined whether the noncompetitive nAChR antagonist mecamylamine had antidepressant-like effects in the forced swim test (FST) and tail suspension test (TST). These experiments were repeated in mice lacking either the beta2- or alpha7-nAChR subunits to identify the nAChR subunits involved in mediating the antidepressant response to mecamylamine.

MATERIALS AND METHODS

Adult mice on the C57BL/6J background were acutely administered mecamylamine i.p. 30 min before testing in the FST or TST.

RESULTS

A dose-response study showed that mecamylamine significantly decreased immobility time in the TST at the 1.0-mg/kg dose but did not alter baseline locomotor activity. The competitive nAChR antagonist dihydro-beta-erythroidine, but not the blood-brain barrier impermeant antagonist hexamethonium, also decreased immobility in the TST. One milligram per kilogram of mecamylamine also significantly decreased time immobile in the FST whereas both beta2- and alpha7-knockout mice were insensitive to the effects of mecamylamine in the FST.

CONCLUSIONS

Decreased activity of central nAChRs has antidepressant-like effects in both the TST and FST and these effects are dependent on both beta2 and alpha7 subunits. Therefore, compounds that decrease nAChR activity may be attractive new candidates for development as antidepressants in humans.

Bupropion attenuates nicotine abstinence syndrome in the rat

RATIONALE

Bupropion reduces discomfort and craving associated with smoking cessation. This study determined whether a rat model of nicotine dependence could detect such nicotine abstinence-alleviating effects.

OBJECTIVES

Experiments determined whether the abstinence-alleviating effects of bupropion were detectable by (1) behavioral abstinence signs precipitated by the nicotinic antagonist mecamylamine, (2) place aversion conditioned to mecamylamine-precipitated nicotine abstinence, and (3) spontaneous behavioral abstinence signs after abrupt nicotine withdrawal.

METHODS

In experiments 1 and 2, nicotine-dependent rats were coinfused for 7 days with 3.15 mg/kg/day nicotine and 20 mg/kg/day bupropion or with nicotine alone. They were then challenged with 1 mg/kg mecamylamine and observed for behavioral abstinence signs (experiment 1) or place aversion conditioned to precipitated abstinence (experiment 2). In experiment 3, rats were nicotine-infused for 7 days as above. A day after termination of nicotine infusion, rats were observed for spontaneous nicotine abstinence signs before and after injection with saline or bupropion.

RESULTS

In experiment 1, rats coinfused with nicotine and bupropion had significantly fewer mecamylamine-precipitated abstinence signs than rats infused with nicotine alone but similar numbers to rats infused with saline alone. In experiment 2, bupropion pretreatment significantly reduced the aversiveness of mecamylamine-precipitated nicotine abstinence. In experiment 3, a single bupropion injection dose-dependently alleviated spontaneous nicotine abstinence syndrome.

CONCLUSIONS

These results suggest that these rat models of nicotine dependence and abstinence syndrome may be useful in detecting nicotine abstinence-alleviating effects of potential medications for smoking cessation. The effects of acute bupropion administration raise interesting questions regarding bupropion's mechanism of action.