The effects of nicotine on neural pathways implicated in depression: a factor in nicotine addiction?

Fetal Exposure to Tobacco Metabolites and Depression During Adulthood: Beyond Binary Measures

BACKGROUND

Sibling studies of maternal smoking during pregnancy and subsequent risk of depression have produced mixed results. A recent study identified not considering the amount of maternal smoking and age of onset as potentially masking a true association. We examine these issues and also the amount of maternal smoking during pregnancy as a determinant of the severity of depressive symptoms.

METHODS

We analyzed data from the community-based National Longitudinal Survey of Youth (US, 1994-2016). Mothers reported smoking during pregnancy (none, <1 pack/day, ≥1 pack/day). We assessed offspring's lifetime depression (i.e., ≥8 symptoms) and symptom counts with the Centers for Epidemiologic Studies Depression scale. We estimated the risk of these two outcomes in the full sample (n = 7172) and among siblings (n = 6145) using generalized linear mixed-effects models with random intercepts by family and family-averaged means for sibling analyses.

RESULTS

Among siblings, we observed dose-dependent elevations for both risk of depression (smoking during pregnancy <1 pack/day adjusted risk ratio [aRR] = 1.18; 95% confidence interval [CI] = 1.07, 1.30; smoking ≥1 aRR = 1.36; 95% CI = 1.19, 1.56) and severity of depressive symptoms (smoking <1 pack/day aRR = 1.12; 95% CI = 1.08, 1.16); smoking ≥1 pack/day aRR = 1.25; 95% CI = 1.18, 1.31). Among both samples, the P for trend was <0.01. In analysis limited to offspring diagnosed before age 18, results for severity were attenuated.

CONCLUSIONS

This evidence supports the existence of an independent association between maternal smoking during pregnancy and both the risk of depression and the severity of depressive symptoms. The results highlight the utility of considering the amount of smoking, severity of symptoms, and age of onset.

Comparison of the associations between Life's Essential 8 and Life's Simple 7 with depression, as well as the mediating role of oxidative stress factors and inflammation: NHANES 2005-2018

BACKGROUND

Cardiovascular health (CVH) is closely associated with depression. However, Life's Essential 8 (LE8), a novel CVH measure, has not yet been clearly linked to depression. This study aims to explore the association between LE8 and depression, compare its advantages over Life's Simple 7 (LS7), and investigate the mediating effects of oxidative stress and inflammation.

METHODS

This study investigated cross-sectional data of adults aged 20 and above from National Health and Nutrition Examination Survey (NHANES) 2005 to 2018. The LE8 score (ranging from 0 to 100) was derived from the American Heart Association's definition, based on the unweighted average of 8 metrics, classified as low cardiovascular health (CVH) (0-49), moderate CVH (50-79), and high CVH (80-100). Similar to LE8, LS7 scores were categorized into inadequate (0-7), average (8-10), or optimal (11-14) after calculating the unweighted mean of each component. Depression was diagnosed using the Patient Health Questionnaire (PHQ-9), with a score of ≥10 defining depression. Adjusted for sociodemographic factors and other risk factors for depression, weighted logistic regression and restricted cubic spline analysis were used to explore the correlation. Receiver operating characteristic (ROC) curves were used to study the associations between CVH scores and depression. Subsequently, subgroup analysis and sensitivity analysis were conducted, followed by an exploration of the mechanisms involved.

RESULTS

A total of 7 cycles from 2005 to 2018 contained complete data. Weighted logistic regression showed that both LS7 and LE8 were significantly associated with depression. Specifically, for LE8, after adjustment, the risk of depression decreased by 52 % for moderate CVH compared to low CVH (OR: 0.48, 95 % CI: 0.41-0.57, P < 0.0001), while the risk decreased by 80 % for high CVH (OR: 0.20, 95 % CI: 0.15-0.26, P < 0.0001, Ptrend < 0.0001). For LS7, after adjustment, compared with inadequate CVH, the risk of depression decreased by 49 % for average CVH (OR: 0.51, 95 % CI: 0.34-0.78, P = 0.002), and by 55 % for optimal CVH (OR: 0.45, 95 % CI: 0.27-0.74, P = 0.002, Ptrend < 0.0001). Area under ROC curves for predicting depression were 0.672 (95 % CI, 0.66-0.684; P < 0.001) and 0.605 (95 % CI, 0.59-0.619; P < 0.001) for LE8 and LS7 (PDeLong < 0.001), respectively. Sensitivity analysis demonstrated the robustness of the association. GGT and WBC jointly mediated 9.62 % of this association (all P < 0.001).

LIMITATIONS

The cross-sectional study cannot infer causality.

CONCLUSIONS

The association between Life's Essential 8 and depression was stronger and more practical. Oxidative stress and inflammation mediate this association. Individuals with extremely poor cardiovascular health have a 7-fold increased risk of depression, highlighting the necessity of maintaining at least moderate cardiovascular health.

Maternal nicotine intoxication before pregnancy induces depressive- and anxiety-like behaviors as well as cognitive deficits in male offspring and correlates with neurobiological changes

INTRODUCTION

Maternal nicotine use has been suggested to affect the behavior of children and is linked to changes in neurological systems; however, the specific mechanism is yet to be understood.

METHODS

Mice were used to establish a maternal nicotine intoxication model. At postnatal day 60 (adolescent stage), male offspring were tested for behavioral tasks including sucrose preference, open field, elevated plus maze, light/dark box, object recognition, Morris water maze (MWM), and forced swimming. Enzyme-linked immunoassays were used to measure plasma concentrations of neurotransmitters including norepinephrine, dopamine, serotonin, and corticosterone. Serotonin transporter (Sert), brain-derived neurotrophic factor (Bdnf), cAMP response element binding protein (Creb), and phosphorylated (p)Creb mRNA levels were measured using quantitative real-time polymerase chain reaction.

RESULTS

Male offspring of nicotine-intoxicated dams had significantly reduced sucrose preference, mobility time in the forced swimming test, and locomotor and exploratory activities. Offspring in the maternal nicotine intoxication group showed increased signs of depressive- and anxiety-like behavior. Recognition memory in the MWM was compromised in these animals. The hippocampal and prefrontal cortical regions showed significant changes in Bdnf, pCreb, and Sert gene expression, whereas CREB mRNA levels were unaffected. Moreover, compared to the controls, neurogenesis and neuronal viability were also reduced in these animals.

CONCLUSION

Prenatal nicotine exposure might affect the hypothalamic-pituitary-adrenal axis and reduce neurogenesis, potentially leading to depressive-like behaviors and cognitive deficiencies in male offspring.

Maternal smoking during pregnancy, offspring smoking, adverse childhood events, and risk of major depression: a sibling design study

BACKGROUND

Evidence of a biologically plausible association between maternal smoking during pregnancy (MSP) and the risk of depression is discounted by null findings from two sibling studies. However, valid causal inference from sibling studies is subject to challenges inherent to human studies of MSP and biases particular to this design. We addressed these challenges in the first sibling study of MSP and depression conducted among adults past the peak age for the onset of depression, utilizing a prospectively collected and biologically validated measure of MSP and accounting for non-shared as well as mediating factors.

METHODS

We fit GEE binomial regression models to correct for dependence in the risk of depression across pregnancies of the same mother. We also fit marginal structural models (MSM) to estimate the controlled direct effect of MSP on depression that is not mediated by the offspring's smoking status. Both models allow the estimation of within- and between-sibling risk ratios.

RESULTS

The adjusted within-sibling risk ratios (RR_W) from both models (GEE: RR_W = 1.97, CI 1.16-3.32; MSM: RR_W = 2.08, CI 1.04-4.17) evinced an independent association between MSP and risk of depression. The overall effects from a standard model evinced lower associations (GEE: RR_T = 1.12, CI 0.98-1.28; MSM: RR_T = 1.18, CI 1.01-1.37).

CONCLUSIONS

Based on within-sibling information free of unmeasured shared confounders and accounting for a range of unshared factors, we found an effect of MSP on the offspring's risk of depression. Our findings, should they be replicated in future studies, highlight the importance of considering challenges inherent to human studies of MSP and affective disorders.

Internalizing and externalizing problems on the age of e-cigarette initiation in youth: Findings from the Population Assessment of Tobacco and Health (PATH), 2013-2017

Previous research has established an association between internalizing and externalizing problems with e-cigarette use in youth. Secondary analysis of Population Assessment of Tobacco and Health youth waves 1-4(2013-2017). Age of initiation of ever e-cigarette use and age of first report of past 30-day e-cigarette use were prospectively estimated among never e-cigarette users(waves 1-3). Weighted interval-censoring multivariable Cox proportional hazard models were fit to assess differences in each e-cigarette outcome among youth with internalizing and externalizing problems, as well as the interaction between internalizing and externalizing problems, while adjusting for covariates. Weighted interval-censoring survival analyses estimated the age of initiation of ever and age of first report of past 30-day e-cigarette use stratified by internalizing and externalizing problems. Among youth never e-cigarette users, those with high internalizing problems and high externalizing problems had increased risk of initiating ever e-cigarette use at earlier ages compared to youth with none/low internalizing and externalizing problems, respectively. Youth with high internalizing problems and high externalizing problems had increased risk of first reporting past 30-day e-cigarette use at earlier ages compared to youth with none/low internalizing problems, respectively. By age 17, 36.3% of youth with high internalizing problems and 38.5% of youth with high externalizing problems initiated ever e-cigarette use. By age 17, 16.8% of youth with high internalizing and 18.7% of youth with high externalizing problems first reported past 30-day e-cigarette use. Youth with internalizing and externalizing problems should be screened for e-cigarette use and provided with proper resources to prevent onset of e-cigarette use.

The interaction of early life factors and depression-associated loci affecting the age at onset of the depression

Multiple previous studies explored the associations between early life factors and the age at onset of the depression. However, they only focused on the influence of environmental or genetic factors, without considering the interactions between them. Based on previous genome-wide association study (GWAS) data, we first calculated polygenic risk score (PRS) for depression. Regression analyses were conducted to assess the interacting effects of depression PRS and 5 early life factors, including felt hated by family member (N = 40,112), physically abused by family (N = 40,464), felt loved (N = 35633), and sexually molested (N = 41,595) in childhood and maternal smoking during pregnancy (N = 38,309), on the age at onset of the depression. Genome-wide environment interaction studies (GWEIS) were then performed to identify the genes interacting with early life factors for the age at onset of the depression. In regression analyses, we observed significant interacting effects of felt loved as a child and depression PRS on the age at onset of depression in total sample (β = 0.708, P = 5.03 × 10^-3) and males (β = 1.421, P = 7.64 × 10^-4). GWEIS identified a novel candidate loci interacting with felt loved as a child at GSAP (rs2068031, P = 4.24 × 10^-8) and detected several genes with suggestive significance association, such as CMYA5 (rs7343, P = 2.03 × 10^-6) and KIRREL3 (rs535603, P = 4.84 × 10^-6) in males. Our results indicate emotional care in childhood may affect the age at onset of depression, especially in males, and GSAP plays an important role in their interaction.

The effect of aerobic exercises of different intensities on anxiety, cigarette addiction, sleep quality, and quality of life in former smokers

BACKGROUND

There is a worldwide struggle to quit smoking and prevent relapsing. Aerobic exercises are frequently utilized to aid in smoking cessation and prevent relapse.

AIMS

This study aimed to investigate the effects of aerobic exercises of different intensity on the level of anxiety, smoking addiction, and quality of sleep and life in former smokers.

METHODS

The study included 60 people aged 18 to 45 who had quit smoking within the previous month. Individuals were randomly assigned to control (CON), mild-intensity aerobic activity (MIA), and moderate-intensity aerobic activity (MoIA) groups. The MIA group did submaximal aerobic exercises at 40% of maximum heart rate (MHR), while the MoIA group did them at 60% of MHR for 8 weeks/3 days. Participants' anxiety levels were assessed using the Beck Anxiety Scale (BAS), smoking addiction was assessed using the Fagerström Test for Nicotine Dependence and Substance Craving Scale (SCS), sleep quality was assessed using the Pittsburgh Sleep Quality Index, and quality of life was assessed using the SF-36 Short Form Scale (SF-36).

RESULTS

The SCS score of the MoIA group declined more than the MIA and CON groups, and the MIA group had a lower sleep disturbance score than other groups when the influence of exercise training was assessed over time (p < 0.05). Aerobic exercise had no influence on SF-36 or BAS scores (p > 0.05).

CONCLUSIONS

The benefits of mild and moderate aerobic exercise on quality of life and anxiety are similar. However, mild-intensity aerobic exercises may be suitable for sleep difficulties while moderate-intensity aerobic exercises may be preferred for reducing smoking addiction.

Comparing the Rate of Nicotine Metabolism Among Smokers With Current or Past Major Depressive Disorder

BACKGROUND AND OBJECTIVES

Persons with current or past major depressive disorder (MDD) vs those without have higher smoking rates. The nicotine metabolite ratio (NMR) represents variation in the rate of nicotine metabolism and has been associated with smoking behaviors and response to tobacco treatments. We compared NMR between smokers with current or past MDD (MDD+) vs smokers without MDD (MDD-). We also assessed correlates of NMR and compared withdrawal and craving between MDD+ and MDD- smokers.

METHODS

Using baseline data from two clinical trials and propensity score weighting based on sex, race, body mass index, and smoking rate, we compared NMR between MDD+ (N = 279) and MDD- (N = 1575) smokers. We also compared groups on and nicotine withdrawal and craving.

RESULTS

Mean NMR (β = -.02, 95% confidence interval [CI]: -0.05 to 0.01, P = .13) and the distribution of smokers across NMR quartiles (odds ratio [OR] = 0.76, 95% CI: 0.50 to 1.16, P = .21) were similar between MDD+ and MDD- samples. This relationship was not affected by antidepressant medication. In the MDD+ sample, African Americans had significantly lower mean NMR, while older smokers and smokers with lower education had higher mean NMR (Ps < .05). MDD+ smokers had significantly higher withdrawal and craving than MDD- smokers (Ps < .05).

DISCUSSION AND CONCLUSIONS

While variability in NMR may not explain differences in smoking rates between MDD+ and MDD- smokers, MDD+ smokers report increased withdrawal and craving.

SCIENTIFIC SIGNIFICANCE

In this first study to assess NMR among MDD+ smokers, the findings underscore the need to address withdrawal and craving within smoking cessation treatments for those with MDD. (Am J Addict 2021;00:00-00).

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.

Predictive Association of Smoking with Depressive Symptoms: a Longitudinal Study of Adolescent Twins

Longitudinal, genetically informative studies of the association between cigarette smoking and depressive symptoms among adolescents are limited. We examined the longitudinal association of cigarette smoking with subsequent depressive symptoms during adolescence in a Finnish twin cohort. We used prospective data from the population-based FinnTwin12 study (maximum N = 4152 individuals, 1910 twin pairs). Current smoking status and a number of lifetime cigarettes smoked were assessed at the age of 14 and depressive symptoms at the age of 17. Negative binomial regression was conducted to model the association between smoking behavior and subsequent depressive symptoms among individuals, and within-pair analyses were conducted to control for unmeasured familial confounding. Analyses were adjusted for age, sex, school grades, drinking alcohol to intoxication, health status, family structure, parental education, and smoking, as well as for pre-existing depressiveness. The results of the individual-level analyses showed that cigarette smoking at the age of 14 predicted depressive symptoms at the age of 17. Compared to never smokers, those who had smoked over 50 cigarettes (incidence rate ratio, IRR = 1.43, 95% CI 1.28–1.60) and regular smokers (IRR = 1.46, 95% CI 1.32–1.62) had higher depression scores. The associations were attenuated when adjusted for measured covariates and further reduced in within-pair analyses. In the within-pair results, the estimates were lower within monozygotic (MZ) pairs compared to dizygotic (DZ) pairs, suggesting that shared genetic factors contribute to the associations observed in individual-based analyses. Thus, we conclude that cigarette smoking is associated with subsequent depressive symptoms during adolescence, but the association is not independent of measured confounding factors and shared genetic influences.

Effects of repetitive transcranial magnetic stimulation on nicotine consumption and craving: A systematic review

We performed a systematic review of the studies employing repetitive transcranial magnetic stimulation (rTMS) in subjects with smoking addiction. High-frequency (HF) rTMS over the prefrontal cortex (PFC), in particular the left dorsolateral PFC (DLPFC), might represent a save and innovative treatment tool for tobacco consumption and craving in nicotine-dependent otherwise healthy people. rTMS can be effective for this indication also in patients with schizophrenia, but the results are conflicting and sufficient evidence from large-scale trials is still lacking. Promising results have been obtained using particular techniques for brain stimulation, such as deep rTMS and theta burst stimulation. Multiple-target HF rTMS can also have a potential in smoking cessation. fMRI and EEG recordings have proven to be useful for objectively assessing the treatment effects. TMS is likely to be most effective when paired with an evidence-based self-help intervention, cognitive-behavioral interventions and nicotine replacement therapy. However, the most recent studies employed different protocols and yielded heterogeneous results, which should be replicated in further controlled studies with larger sample sizes and rigorous standards of randomization. To date, no recommendation other than that a possible efficacy of HF-rTMS of the left DLPFC can be made for alternative rTMS procedures in nicotine craving and consumption.

Testing the reciprocal association between smoking and depressive symptoms from adolescence to adulthood: A longitudinal twin study

BACKGROUND

Longitudinal studies enhance understanding of the complex reciprocal relationship between smoking and depression from adolescence to young adulthood. Examining bi-directional associations between cigarette smoking and depressive symptoms in a genetically informative twin design can help to understand whether the associations are independent of shared genetic and environmental factors.

METHODS

We analyzed longitudinal data on smoking and depressive symptoms in twins participating in the adolescent (mean age 17.5) and young adult (mean age 21.9) surveys of the FinnTwin12 study (maximum N = 2,954 individuals; 1,154 twin pairs). At both waves, self-reported depressive symptoms, assessed with the 10-item version of the General Behavior Inventory (GBI), and smoking status were analyzed. The bi-directional associations were first studied among individuals and then within monozygotic and dizygotic twin pairs.

RESULTS

When adjusted for multiple covariates and baseline depressive symptoms, daily smokers at age 17 had higher depressive symptom scores at age 22 than never smokers (Incidence Rate Ratio = 1.17, 95% CI: 1.03-1.33). Similarly, when adjusted for covariates and baseline smoking, higher score in GBI at age 17 was associated with an increased likelihood of being a non-daily (Relative Risk Ratio (RRR) = 1.06, 95% CI: 1.01-1.11) or daily (RRR = 1.05, 95% CI: 1.00-1.10) smoker at age 22. No associations were found in within-pair analyses, suggesting that the individual-level association is explained by shared familial liabilities.

CONCLUSION

During the developmental period from adolescence to adulthood, cigarette smoking and depressive symptoms are reciprocally associated. However, these associations are confounded by shared genetic and other familial liabilities.

Nicotine and cigarette smoke modulate Nrf2-BDNF-dopaminergic signal and neurobehavioral disorders in adult rat cerebral cortex. Hum Exp Toxicol 2018;37:540-556. [PMID: 28641491 DOI: 10.1177/0960327117698543]

BACKGROUND

Nicotine and cigarette smoking (CS) are associated with addiction behavior, drug-seeking, and abuse. However, the mechanisms that mediate this association especially, the role of brain-derived neurotrophic factor (BDNF), dopamine (DA), and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling in the cerebral cortex, are not fully known. Therefore, we hypothesized that overexpression of BDNF and DA, and suppression of Nrf2 contribute to several pathological and behavioral alterations in adult cerebral cortex. Methodology/Principal Observations: We treated Wistar rats with different doses of oral nicotine and passive CS for 4-week (short-term) and 12-week (long-term) duration, where doses closely mimic the human smoking scenario. Our result showed dose-dependent association of anxiogenic and depressive behavior, and cognitive interference with neurodegeneration and DNA damage in the cerebral cortex upon exposure to nicotine/CS as compared to the control. Further, the results are linked to upregulation of oxidative stress, overexpression of BDNF, DA, and DA marker, tyrosine hydroxylase (TH), with concomitant downregulation of ascorbate and Nrf2 expression in the exposed cerebral cortex when compared with the control.

CONCLUSION/SIGNIFICANCE

Overall, our data strongly suggest that the intervention of DA and BDNF, and depletion of antioxidants are important factors during nicotine/CS-induced cerebral cortex pathological changes leading to neurobehavioral impairments, which could underpin the novel therapeutic approaches targeted at tobacco smoking/nicotine's neuropsychological disorders including cognition and drug addiction.

Effects of the phencyclidine model of schizophrenia and nicotine on total and categorized ultrasonic vocalizations in rats

Patients with schizophrenia smoke cigarettes at a higher rate than the general population. We hypothesized that a factor in this comorbidity is sensitivity to the reinforcing and reinforcement-enhancement effects of nicotine. Phencyclidine (PCP) was used to model behavioral changes resembling negative symptoms of schizophrenia in rats. Ultrasonic vocalizations (USVs) in rats have been used to measure emotional states, with 50 kHz USVs indicating positive states and 22 kHz USVs indicating negative states. Total and categorized numbers of 22 and 50 kHz USVs and USVs during a visual stimulus (e.g. a potential measure of reinforcement-enhancement) were examined in rats following injection of PCP (2.0 mg/kg) and/or nicotine (0.2 or 0.4 mg/kg) daily for 7 days. PCP was then discontinued and all rats received nicotine (0.2 and 0.4 mg/kg) and PCP (2.0 mg/kg) on three challenge days. PCP acutely decreased 50 kHz vocalizations, whereas repeated nicotine potentiated rates of vocalizations, with similar patterns during light presentations. Rats in the PCP and nicotine combination groups made more 50 kHz vocalizations compared with rats in the control groups on challenge days. We conclude that PCP may produce a reward deficit, which is shown by decreased 50 kHz USVs, and behaviors post-PCP exposure may best model the comorbidity between schizophrenia and nicotine.

Young adults report increased pleasure from smoking cigarettes when drinking alcohol but not when using marijuana

BACKGROUND

Among young adults, cigarette smoking is strongly associated with alcohol and marijuana use. The present study compared self-reported co-use of cigarettes and alcohol versus cigarettes and marijuana among young adults using cross-sectional survey data.

METHODS

Participants were young adult cigarette smokers (age 18 to 25) who also reported past month alcohol or marijuana use enrolled in a randomized trial testing a smoking cessation intervention on Facebook. Participants self-reported extent of cigarette smoking under the influence of alcohol or marijuana and differences in perceived pleasure from cigarette smoking when drinking alcohol compared to using marijuana.

RESULTS

Among cigarette smokers who drank alcohol and used marijuana in the past month (n=200), a similar percentage of cigarettes were smoked under the influence of alcohol (42.4%±31.2%) and marijuana (43.1% ±30.0%). Among alcohol + marijuana users, perceived pleasure from smoking cigarettes was significantly greater when drinking alcohol versus when using marijuana (t₍₁₉₉₎=7.05, p<0.001). There was, on average, an increase in perceived pleasure from smoking cigarettes when drinking alcohol, though perceived pleasure did not differ by binge drinking frequency. In contrast, there was on average no change in perceived pleasure from smoking cigarettes when using marijuana. Results from the cigarette smokers who used alcohol + marijuana were similar to cigarette smokers who only used alcohol (n=158) or only used marijuana (n=54).

CONCLUSION

Findings highlight greater perceived reward from smoking cigarettes when drinking alcohol compared to when using marijuana, informing smoking cessation interventions that target users of multiple substances.

Association between smoking behaviour and genetic variants of glial cell line-derived neurotrophic factor

Glial cell line-derived neurotrophic factor (GDNF) promotes development and differentiation of dopaminergic neurons, thus it has an important role in dopamine-related neuropsychiatric disorders. Since the role of dopamine system in smoking is well established, we hypothesized that GDNF gene variants may affect smoking behaviour. Self-reported data on smoking behaviour (never smoked, quit, occasional, or regular smokers) and level of nicotine addiction (Hooked on Nicotine Checklist and Fagerstrom Nicotine Addiction Scale), anxiety, as well as buccal samples were obtained from 930 Hungarian young adults (18-35 years). Genetic analysis involved eight GDNF single-nucleotide polymorphisms (SNP) (rs1981844, rs3812047, rs3096140, rs2973041, rs2910702, rs1549250, rs2973050 and rs11111). Allele-wise association analyses of the eight GDNF SNPs provided a significant association between smoking behaviour and rs3096140 (P=0.0039). The minor allele (C) was more frequent in those groups who smoked in some form (quit, occasional or regular smokers) as compared to those who never smoked (P = 0.0046). This result remained significant after Bonferroni correction for multiple testing. In the ever smoking group, no significant differences were found in the level of nicotine addiction by the alleles of these polymorphisms. Also, no significant interaction of rs3096140 and smoking categories were observed on anxiety mean scores. Although previous data demonstrated an association between GDNF rs2910704 and severity of methamphetamine use to the best of our knowledge, this is the first study on the role of GDNF genetic variations in smoking behaviour. Our results suggest that GDNF rs3096140 might be involved in the genetic background of smoking, independent of anxiety characteristics.

Not Only When Feeling Down: The Relationship Between Mood Intensity and Smoking Behavior

BACKGROUND

There is substantial empirical evidence that negative mood triggers smoking behavior, and less support for the similar effect of positive mood. However, the relationship between the intensity of mood and smoking remains relatively under-researched.

OBJECTIVES

The present study explored the association between mood intensity and smoking behavior.

METHODS

Seventy-three ad libitum smokers recorded their mood and concurrent number of smoked cigarettes three times daily for one week using electronic diary application. Real time assessment in natural environment enabled greater reliability, validity and generalizability of the collected data.

RESULTS

We analyzed results using within-subjects approach and obtained significant growth trend in smoking behavior that concurred with the increase of mood intensity-smokers tended to increase their consumption of cigarettes when they were feeling either happy or sad in comparison to the situation when they were in neutral mood.

IMPORTANCE

These findings raise implications regarding the role of mood intensity in initiating smoking behavior.

Cigarette smoking and depression comorbidity: systematic review and proposed theoretical model

BACKGROUND AND AIMS

Despite decades of research on co-occurring smoking and depression, cessation rates remain consistently lower for depressed smokers than for smokers in the general population, highlighting the need for theory-driven models of smoking and depression. This paper provides a systematic review with a particular focus upon psychological states that disproportionately motivate smoking in depression, and frame an incentive learning theory account of smoking-depression co-occurrence.

METHODS

We searched PubMed, Scopus, PsychINFO and CINAHL to December 2014, which yielded 852 papers. Using pre-established eligibility criteria, we identified papers focused on clinical issues and motivational mechanisms underlying smoking in established, adult smokers (i.e. maintenance, quit attempts and cessation/relapse) with elevated symptoms of depression. Two reviewers determined independently whether papers met review criteria. We included 297 papers in qualitative synthesis.

RESULTS

Our review identified three primary mechanisms that underlie persistent smoking among depressed smokers: low positive affect, high negative affect and cognitive impairment. We propose a novel application of incentive learning theory which posits that depressed smokers experience greater increases in the expected value of smoking in the face of these three motivational states, which promotes goal-directed choice of smoking behavior over alternative actions.

CONCLUSIONS

The incentive learning theory accounts for current evidence on how depression primes smoking behavior and provides a unique framework for conceptualizing psychological mechanisms of smoking maintenance among depressed smokers. Treatment should focus upon correcting adverse internal states and beliefs about the high value of smoking in those states to improve cessation outcomes for depressed smokers.

Smoking status as a predictor of antidepressant medication use

BACKGROUND

Cigarette smoking and depression are major public health concerns, but longitudinal research on the association between smoking and antidepressant use is scarce. The purpose of this study was to investigate, whether smoking predicts antidepressant medication during a 10-year follow-up.

METHODS

A questionnaire was administered to Finnish adult twins in 1990. Antidepressant prescription data during 1995-2004 were obtained from the register of the Finnish Social Insurance Institution and linked to the survey data. Cox Proportional Hazard Models among 10,652 individuals (1075 cases, 9577 controls) assessed the risk for depression in the cohort, whereas within-pair comparisons of smoking twins with their non-smoking co-twins controlled for shared familial influences.

RESULTS

Daily smokers had a significantly elevated likelihood for having antidepressant prescriptions in the follow-up. Based on the analysis among those without baseline depression, heavy daily smokers had a significantly elevated likelihood (HR 1.56, 95% CI 1.17-2.08) for antidepressant prescription when adjusted for all confounders. Similar analysis using pairs discordant for antidepressant medication confirmed that daily smoking twins had a higher likelihood for prescriptions (HR 1.98, 95% CI 1.11-3.54) compared with their non-smoking co-twins. The estimates were for MZ pairs (HR 1.78, 95% CI 0.48-6.55) and DZ pairs (HR 1.92, 95% CI 0.99-3.72), respectively.

LIMITATIONS

Changes in smoking status after baseline cannot be accounted for. Reversed association between depression and smoking cannot be ruled out.

CONCLUSION

Daily smoking predicts antidepressant medication, even when controlling for essential confounders and familial factors. This study highlights the need of systematically assessing depressive symptoms among smokers.

Reduced Blood Serotonin Levels in Chronic Central Serous Chorioretinopathy

PURPOSE

To evaluate blood serotonin (5-hydroxytryptamine [5-HT]) levels in patients with chronic central serous chorioretinopathy (CSC).

DESIGN

A case-controlled retrospective study.

PARTICIPANTS

Forty-nine patients with CSC and 30 age-matched control subjects.

METHODS

Blood 5-HT levels were measured using high-performance liquid chromatography.

MAIN OUTCOME MEASURES

Blood 5-HT levels in patients with acute or chronic CSC were measured at the initial visit and compared with those in controls.

RESULTS

The blood 5-HT level (98.2±27.5 ng/ml) in patients with chronic CSC was significantly lower than those in patients with acute CSC (122.5±23.9 ng/ml, P = 0.0081) and controls (128.5±35.8 ng/ml, P = 0.0013). After adjusting for covariates, patients with decreased blood 5-HT levels were found to be more likely to develop chronic CSC (odds ratio, 0.97; 95% confidence interval, 0.95-0.99; P = 0.009).

CONCLUSIONS

These results suggest that serotonin may have a role in chronic CSC pathogenesis and is associated with disease progression.

Alpha7 nicotinic acetylcholine receptor agonists and PAMs as adjunctive treatment in schizophrenia. An experimental study

Nicotine has been found to improve cognition and reduce negative symptoms in schizophrenia and a genetic and pathophysiological link between the α7 nicotinic acetylcholine receptors (nAChRs) and schizophrenia has been demonstrated. Therefore, there has been a large interest in developing drugs affecting the α7 nAChRs for schizophrenia. In the present study we investigated, in rats, the effects of a selective α7 agonist (PNU282987) and a α7 positive allosteric modulator (PAM; NS1738) alone and in combination with the atypical antipsychotic drug risperidone for their utility as adjunct treatment in schizophrenia. Moreover we also investigated their utility as adjunct treatment in depression in combination with the SSRI citalopram. We found that NS1738 and to some extent also PNU282987, potentiated a subeffective dose of risperidone in the conditioned avoidance response test. Both drugs also potentiated the effect of a sub-effective concentration of risperidone on NMDA-induced currents in pyramidal cells of the medial prefrontal cortex. Moreover, NS1738 and PNU282987 enhanced recognition memory in the novel object recognition test, when given separately. Both drugs also potentiated accumbal but not prefrontal risperidone-induced dopamine release. Finally, PNU282987 reduced immobility in the forced swim test, indicating an antidepressant-like effect. Taken together, our data support the utility of drugs targeting the α7 nAChRs, perhaps especially α7 PAMs, to potentiate the effect of atypical antipsychotic drugs. Moreover, our data suggest that α7 agonists and PAMs can be used to ameliorate cognitive symptoms in schizophrenia and depression.

The impact of quitting smoking on depressive symptoms: findings from the International Tobacco Control Four-Country Survey

AIMS

To determine whether abstinence or relapse on a quit attempt in the previous year is associated with current depressive symptoms.

DESIGN

Prospective cohort with approximately annual waves. Mixed-effect logistic regressions tested whether time 2 (T2) quitting status was associated with reporting symptoms at T2, and whether time 1 (T1) symptoms moderated this relationship.

SETTING

Waves 5-8 of the Four-Country International Tobacco Control Study: a quasi-experimental cohort study of smokers from Canada, the United States, the United Kingdom and Australia.

PARTICIPANTS

A total of 6978 smokers who participated in telephone surveys.

MEASUREMENTS

T1 and T2 depressive symptoms in the last 4 weeks were assessed with two screening items from the PRIME-MD questionnaire. Quitting status at T2: (1) no attempt since T1; (2) attempted and relapsed; and (3) attempted and abstinent at T2.

FINDINGS

Compared with no attempt, relapse was associated with reporting T2 symptoms [odds ratio (OR) = 1.46, 95% confidence interval (CI) = 1.33, 1.59]). Associations between T2 quitting status and T2 symptoms were moderated by T1 symptoms. Relapse was associated positively with T2 symptoms for those without T1 symptoms (OR = 1.71, 95% CI = 1.45, 2.03) and those with T1 symptoms (OR = 1.45, 95% CI = 1.23, 1.70). Abstinence was associated positively for those without T1 symptoms (OR = 1.37, 95% CI = 1.10, 1.71) and negatively for those with T1 symptoms (OR = 0.74, 95% CI = 0.59, 0.94). Age moderated these associations significantly. Relapse did not predict T2 symptoms for those aged 18-39 irrespective of T1 symptoms. The negative effect of abstinence on T2 symptoms for those with T1 symptoms was significant only for those aged 18-39 (OR = 0.61, 95% CI = 0.40, 0.94) and 40-55 (OR = 0.58, 95% CI = 0.40, 0.84). The positive effect of abstinence on T2 symptoms for those without T1 symptoms was significant only for those aged more than 55 (OR =1.97, 95% CI = 1.35, 2.87).

CONCLUSIONS

Most people who stop smoking appear to be at no greater risk of developing symptoms of depression than if they had continued smoking. However, people aged more than 55 who stop smoking may be at greater risk of developing symptoms of depression than if they had continued smoking.

Cigarette Smoking and Tryptophan Hydroxylase 2 mRNA in the Dorsal Raphe Nucleus in Suicides

Cigarette smoking is associated with suicide and mood disorders and stimulates serotonin release. Tryptophan hydroxylase (TPH2) synthesizes serotonin and is over-expressed in suicides. We determined whether smoking is associated with TPH2 mRNA in suicides and controls. TPH2 mRNA was measured postmortem in the dorsal raphe nucleus (DRN) of controls (N = 26, 17 nonsmokers and nine smokers) and suicides (N = 23, 5 nonsmokers and 18 smokers). Psychiatric history was obtained by psychological autopsy. TPH2 mRNA was greater in suicide nonsmokers than suicide smokers, control smokers and control nonsmokers (p = 0.006). There was more TPH2 mRNA throughout the DRN. Smoking interferes with the TPH2 mRNA increase observed in suicide nonsmokers. The absence of altered TPH2 expression in non-suicide smokers suggests no pharmacological effect of smoking.

A Review of Impact of Tobacco Use on Patients with Co-occurring Psychiatric Disorders

Consumption of tobacco has been a worldwide problem over the past few decades due to the highly prevalent tobacco-attributable complications. Tobacco use has also been found to be more prevalent in patients with psychiatric disorders. Therefore, we conducted this review about the impact of tobacco use on co-occurring psychiatric disorders. Various facets of this interaction between tobacco use among those with co-occurring psychiatric disorders have been explored. It has been found that people with psychiatric disorders have a higher chance of currently smoking tobacco and lesser chance of cessation. Tobacco use and mental disorders continue to share a complex relationship that has been further evolving after the change in the pattern of tobacco use and also the advent of newer modalities of treatment. However, at the same time, it is believed that cessation of smoking may lead to improvement in the symptoms of mental illness.

Psychiatric comorbidity in adolescent electronic and conventional cigarette use

The popularity of electronic (e-) cigarettes has greatly increased recently, particularly in adolescents. However, the extent of psychiatric comorbidity with adolescent e-cigarette use and dual use of conventional (combustible) and e-cigarettes is unknown. This study characterized psychiatric comorbidity in adolescent conventional and e-cigarette use. Ninth grade students attending high schools in Los Angeles, CA (M age = 14) completed self-report measures of conventional/e-cigarette use, emotional disorders, substance use/problems, and transdiagnostic psychiatric phenotypes consistent with the NIMH-Research Domain Criteria Initiative. Outcomes were compared by lifetime use of: (1) neither conventional nor e-cigarettes (non-use; N = 2557, 77.3%); (2) e-cigarettes only (N = 412, 12.4%); (3) conventional cigarettes only (N = 152, 4.6%); and (4) conventional and e-cigarettes (dual use; N = 189, 5.6%). In comparison to adolescents who used conventional cigarettes only, e-cigarette only users reported lower levels of internalizing syndromes (depression, generalized anxiety, panic, social phobia, and obsessive-compulsive disorder) and transdiagnostic phenotypes (i.e., distress intolerance, anxiety sensitivity, rash action during negative affect). Depression, panic disorder, and anhedonia were higher in e-cigarette only vs. non-users. For several externalizing outcomes (mania, rash action during positive affect, alcohol drug use/abuse) and anhedonia, an ordered pattern was observed, whereby comorbidity was lowest in non-users, moderate in single product users (conventional or e-cigarette), and highest in dual users. These findings: (1) raise question of whether emotionally-healthier ('lower-risk') adolescents who are not interested in conventional cigarettes are being attracted to e-cigarettes; (2) indicate that research, intervention, and policy dedicated to adolescent tobacco-psychiatric comorbidity should distinguish conventional cigarette, e-cigarette, and dual use.

Intra-nucleus-accumbens SKF38393 improved the impaired acquisition of morphine-conditioned place preference in depression-like rats

Dopaminergic activity in the nucleus accumbens (NAc) and the globus pallidus (GP) is important for the interaction between depression and addiction, with D1- and D2-like receptors playing different roles. Here, we address the effect of depression on morphine reward and its underlying D1- and D2-like effects in the NAc and/or the GP. Novelty-seeking behaviors and the forced open-space swimming test were used to assess a depression-like state in rats that had undergone chronic mild restraint. Depression-like rats were then trained with morphine-induced conditioned place preference (CPP, 3 mg/kg, 4 days), and showed impaired acquisition of the CPP compared with controls. To examine the receptor-specific dopaminergic mechanism underlying this phenomenon, we microinjected the D1-like agonist SKF38393 (1 μg/side) or the D2-like agonist quinpirole (1 μg/side) into the NAc or the GP. The impairment in acquisition of CPP was reversed only by injecting the D1- but not the D2-like agonist in the NAc. These results suggest that enhancement of dopaminergic transmission in the NAc (via D1-like receptors) may be effective in recovering impaired reward learning during a depression-like state.

Self-affirmation theory and cigarette smoking warning images

INTRODUCTION

The present study examined self-affirmation theory, cigarette smoking, and health-related images depicting adverse effects of smoking. Previous research examining self-affirmation and negative health-related images has shown that individuals who engage in a self-affirmation activity are more receptive to messages when compared to those who do not affirm. We were interested in examining the extent to which self-affirmation would reduce defensive responding to negative health images related to cigarette smoking.

METHODS

Participants included 203 daily smokers who were undergraduate students at a large southern university. Participants completed a battery of questionnaires and were then randomly assigned to one of four conditions (non-smoking image control, smoking image control, low affirmation, and high affirmation). Analyses evaluated the effectiveness of affirmation condition as it related to defensive responding.

RESULTS

Results indicated that both affirmation conditions were effective in reducing defensive responding for those at greatest risk (heavier smokers) and those more resistant to health benefits associated with quitting.

CONCLUSIONS

Findings are discussed in terms of potential public health implications as well as the role defensive responding plays in the evaluation and processing of negative health messages.

The prevalence and socio-demographic correlates of depressive symptoms among Cypriot university students: a cross-sectional descriptive co-relational study

BACKGROUND

Previous findings in the literature suggest that the occurrence of depressive symptoms among university students is associated with specific socio-demographic characteristics. No related research studies have been conducted among university students in Cyprus. The current study aims to add more evidence to the literature by estimating the prevalence of clinical depressive symptoms and their association with individual, parental, academic and health-related behavior characteristics.

METHODS

A descriptive cross sectional study with internal comparison was performed. The occurrence of depressive symptoms was assessed by the Center for Epidemiology Studies - Depression Scale (CES-D). Clinical depressive symptoms were reported as CES-D values ≥ 20. The socio-demographic and other characteristics of the participants were assessed using a questionnaire specifically designed for the present study. Both questionnaires were completed anonymously and voluntarily by 1,500 students (29.9% males and 70.1% females, response rate 85%).

RESULTS

The prevalence of clinical depressive symptoms [CES-D score ≥ 20] was 27.9%. Among other, strong positive associations with clinical depressive symptoms were observed with a) positive personal and family history of depression (OR 2.85, 95% CI: 1.77 - 4.60), b) self -assessed poor physical and mental health (OR 11.30, 95% CI: 7.05 - 18.08). Moreover, students with learning disabilities, as well as those who were dissatisfied with the major under study, the quality of the educational system, the living arrangement, their social life and the available university facilities (OR 2.73, 95% CI: 2.00 - 3.72) were more likely to report clinical depressive symptoms.

CONCLUSIONS

The results of the present study highlight specific individual, parental, academic and health-related behavior characteristics of the students associated with the presence of depressive symptoms. Thus, targeted interventions considering the socio-demographic profile of vulnerable students for early recognition and manifestation of mental health disturbances may be designed. Moreover, the relatively high prevalence of clinical symptoms of depression within this particular cultural context may warrant further investigation in longitudinal studies.

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.

Smoking behaviour and mental health disorders--mutual influences and implications for therapy

Tobacco use is strongly associated with a variety of psychiatric disorders. Smokers are more likely than non-smokers to meet current criteria for mental health conditions, such as mood disorders, anxiety disorders and psychosis. Evidence also suggest that smokers with psychiatric disorders may have more difficulty quitting, offering at least a partial explanation for why smoking rates are higher in this population. The mechanisms linking mental health conditions and cigarette smoking are complex and likely differ across each of the various disorders. The most commonly held view is that patients with mental health conditions smoke in an effort to regulate the symptoms associated with their disorder. However some recent evidence suggests that quitting smoking may actually improve mental health symptoms. This is particularly true if the tobacco cessation intervention is integrated into the context of ongoing mental health treatment. In this paper we reviewed and summarized the most relevant knowledge about the relationship between tobacco use and dependence and psychiatric disorders. We also reviewed the most effective smoking cessation strategies available for patients with psychiatric comorbidity and the impact of smoking behavior on psychiatric medication.

Major depressive episode among Brazilian adults: a cross-sectional population-based study

BACKGROUND

Despite the fact that there is extensive scientific research on depression very few population-based studies have been conducted in Brazilian cities.

METHODS

A sampling design of two-stage conglomerates with probability proportional to size. All adults aged 20 or more living in the selected households were invited to participate in the study. Depression was assessed using the Patient Health Questionnaire-9 (PHQ-9) with a cutoff ≥9.

RESULTS

The study sample comprised 2925 respondents. The prevalence of depression in the sample studied was 20.4% (95% CI 18.9;21.8). After adjustment for confounding factors according to a conceptual analysis model the following variables were associated with a higher prevalence of depression: female gender; younger age; white skin color; lower socioeconomic condition; lower education; smoking; being single or separated; being unemployed; and reporting a heart condition. Alcohol use, arterial hypertension, and diabetes mellitus were not found to be associated with depression.

LIMITATIONS

The difference in the proportion of males among losses and refusals compared to that in the sample analyzed. Another limitation is reverse causality bias that is a problem inherent to cross-sectional studies.

CONCLUSIONS

Our findings support the relevance of depression as a prevalent condition among adults. It also provided evidence of the factors associated with depression, and that some are potentially modifiable risk factors may have implications for policy and health service planning.

Enhanced smoking cue salience associated with depression severity in nicotine-dependent individuals: a preliminary fMRI study

The association between cigarette smoking and depression has been well documented; however, little research has been done to elucidate the neurobiological substrates of this highly prevalent comorbidity. We used multiple linear regression analysis to evaluate the relationship between depression severity as assessed by the Hamilton Depression Rating Scale (HAMD) and blood oxygen level-dependent (BOLD) responses to visual smoking cues in drug-free nicotine-dependent smokers (n=18). Two functional magnetic resonance imaging (fMRI) scans were completed over a single study day, following overnight smoking abstinence (pre-smoking scan) and after cigarette reinstatement (post-smoking scan). During the pre-smoking scan positive correlations between BOLD activity and HAMD scores were observed in areas of the mesocorticolimbic dopaminergic system [inferior frontal gyrus, middle frontal gyrus (MFG), hippocampus (HC), anterior cingulate gyrus] and areas of the visuospatial attention circuit (medial occipital lobe, middle cingulate cortex, superior frontal gyrus, angular gyrus). During the post-smoking scan positive correlations were observed in areas of the brain implicated in drug expectancy (MFG), memory (HC), attentional motivation (posterior cingulate cortex), and visual processing and attention (precuneus). These preliminary findings demonstrate that smokers with higher depression severity attribute greater incentive salience to smoking-related cues and this is especially pronounced during periods of acute abstinence. Such enhanced salience of smoking cues, even after smoking a cigarette, may play a critical role both in the maintenance of smoking in depression and in greater levels of nicotine dependence seen in this patient population.

Effects of asthma on nicotine dependence development and smoking cessation attempts in adolescence

OBJECTIVE

The aim of this study was to investigate whether asthma predicts the development of nicotine dependence and unsuccessful smoking cessation attempts in adolescent smokers. In addition, whether nicotine dependence could explain the relation between asthma and unsuccessful cessation attempts was also investigated.

METHODS

A longitudinal survey study was conducted among 286 adolescents (aged 12-15 at T1) who had never used tobacco at baseline and were current smokers at follow-up 22 months later. Regression analyses were applied to test the effects of four asthma indicators (current wheeze, indication of asthma, symptom severity, and current diagnosed asthma) on nicotine dependence and smoking cessation attempts.

RESULTS

Both adolescents who had an indication of asthma as well as adolescents with higher symptom severity developed higher levels of nicotine dependence over time and made a greater number of unsuccessful smoking cessation attempts in the past 12 months compared to those without asthma or less severe symptoms. Nicotine dependence partly mediated the effects of asthma symptoms on unsuccessful cessation attempts. Current wheezing and current diagnosed asthma did not predict nicotine dependence or unsuccessful quit attempts.

CONCLUSIONS

Nicotine dependence develops more quickly in youth with symptoms of asthma, and this partly explains the increased number of unsuccessful cessation attempts of adolescents with asthma. Smoking prevention and smoking cessation programs are encouraged to provide additional support for youth with asthma, focusing on both the physiological and psychological aspects of dependence.

A twin study of depression and nicotine dependence: shared liability or causal relationship?

BACKGROUND

The nature of the relationship between major depression (MD) and phenotypes related to smoking behavior, including nicotine dependence (ND), is complicated. We present results from analyses comparing models wherein MD and ND are influenced by a shared latent factor to one in which causal pathways between phenotypes are examined.

METHOD

Data were collected for 2906 adult male twins from a population-based sample. Structural equation modeling was used to derive path estimates for shared liability and causal models. MD was assessed according to DSM-III-R diagnostic criteria; ND was assessed using the Fagerstrom Test for Nicotine Dependence (FTND).

RESULTS

The best fitting shared liability model included genetic, but not environmental, influences shared between MD and FTND; a small proportion of these shared influences were also common to smoking initiation. The best fitting causal model included a unidirectional causal path from FTND to MD, with no direct genetic correlation between MD and smoking initiation. Model fit statistics indicated that these models provided nearly identical fits to the data, with the causal model providing a slightly superior AIC value.

CONCLUSIONS

The phenotypic association between MD and FTND is likely due to both a causal relationship, wherein increasing levels of nicotine dependence increase one's risk for depression, and to a shared genetic liability between the two.

LIMITATIONS

This sample consists of Caucasian males born in Virginia, and findings might not be generalizable to others. Statistical power was less than ideal.

Effects of nicotine dependence and depressive symptoms on smoking cessation: a longitudinal study among adolescents

INTRODUCTION

Nicotine dependence has been shown to hamper successful smoking cessation in adolescents. Nicotine dependence and depression are highly comorbid, but the relation between depression and smoking cessation is not yet fully understood. Therefore, the present study examines both the longitudinal reciprocal relation between nicotine dependence and depressive symptoms, and the longitudinal effect of these factors on successful smoking cessation and number of quit attempts.

METHODS

A 2-wave longitudinal study was conducted among 535 adolescents aged 13-18. Written self-report questionnaires were administered in a classroom setting. Two models were tested, examining the mutual relation between nicotine dependence and depressive symptoms, as well as the predictive value of these factors on smoking cessation (n = 535), and number of quit attempts (n = 473) 1 year later.

RESULTS

Adolescents with more depressive symptoms have significantly higher levels of nicotine dependence 1 year later. Higher levels of nicotine dependence negatively predicted subsequent successful smoking cessation, whereas depressive symptoms did not. In contrast, depressive symptoms predicted a higher number of unsuccessful quit attempts in the following year, whereas nicotine dependence did not.

CONCLUSIONS

The findings suggest that adolescents tend to smoke cigarettes in order to diminish their depressive feelings, which might provide some support for the self-medication theory. Smoking cessation programs aiming at adolescents should not only focus on symptoms of nicotine dependence but should also pay attention to depressive feelings, since these feelings are related to a higher number of unsuccessful quit attempts.

Serotonin involvement in Rhodiola rosea attenuation of nicotine withdrawal signs in rats

Rhodiola rosea has been used for centuries in the traditional medicine to stimulate nervous system, to enhance physical and mental performance and to treat fatigue. It is known that administration of Rhodiola rosea extract elicits antidepressant activity, but the mechanism of action still remains unclear. Evidence from animal models and human studies show that nicotine reduces symptoms of depression and that nicotine cessation induces depressive-like symptoms. We investigated the effects of Rhodiola rosea on nicotine withdrawal signs. Nicotine dependence was induced by subcutaneous nicotine injection (2 mg/kg, four times daily) for 14 days. Another group of animals treated with nicotine (for 14 days) and successively with Rhodiola rosea extract was co-administered with selective 5-HT receptorial antagonist WAY 100635 (1 mg/kg). After nicotine withdrawal animals were evaluated for behavioural parameters (locomotor activity, abstinence signs, marble burying test), diencephalic serotonin metabolism and serotonin receptor-1A expression. Results show a significant increase of 5-HT content in N treated with R. rosea, with a significant increase of serotonin receptor 1A, suggesting an involvement of serotonin in beneficial effects of R. rosea on suffering produced by nicotine withdrawal.

Neural expression of nicotine's antidepressant properties during tryptophan depletion: an EEG study in healthy volunteers at risk for depression

Nicotine amelioration of serotonergically mediated mood dysregulation may contribute to the comorbidity between cigarette smoking and depression, a disorder which is associated with aberrant activation and hemispheric asymmetry in frontal and posterior cortical regions. This randomized, double-blind study in 20 healthy volunteers with a positive family history of depression examined the effects of transdermal nicotine on mood and EEG changes accompanying transient reductions in serotonin induced by acute tryptophan depletion (ATD). Increased self-ratings of depressed mood and elevation in left frontal high alpha power (decreased activation) were evidenced with ATD (vs. balanced mixture) in participants treated with the placebo but not the nicotine treated group. Nicotine alone increased vigor and posterior high alpha bilaterally, and during ATD it prevented the reduction in left frontal high alpha that was evident in the placebo patch group. These findings indicate that in depression prone individuals, nicotine acts to stabilize the mood lowering and associated frontal functional asymmetry elicited by an acute decrease in brain serotonin.

Persistent heavy smoking as risk factor for major depression (MD) incidence--evidence from a longitudinal Canadian cohort of the National Population Health Survey

BACKGROUND

Reports of bidirectional associations between smoking and major depression (MD) have been interpreted as providing evidence for confounding by shared-vulnerability factors (SV) that predispose individuals to both conditions. If this is true, then smoking cessation may not reduce the risk of MD. From clinical practice and public health perspectives, the long-term outcomes associated with smoking persistence and cessation are potentially important and deserve exploration. To this end, the 12-year risk of MD in persistent heavy smokers and abstainers who were former-heavy smokers with and without adjustment for potential confounders were compared.

METHODS

Follow-up data from the National Population Health Survey (NPHS) was used. Multinomial logistic (ML) models were fit to identify potential confounders. Using proportional hazard (PH) models, unadjusted and adjusted hazard ratios (HRs) for MD outcome were estimated for different smoking patterns.

RESULTS

The unadjusted HR relating the risk of MD among current-heavy versus former-heavy smokers was 4.3 (95% CI: 2.6-6.9, p < 0.001). Current-heavy smoking predicted onset of MD (HR = 3.1, 95% CI: 1.9-5.2, p < 0.001) even after adjustment for age, sex and stress - the main confounders. However, this was not the case for the never, former-light, and current-light categories. Evidence of decreased risk of MD among former-heavy relative to current-heavy smokers as function of smoking cessation maintenance time was also found.

CONCLUSIONS

Contrary to common beliefs about the benefits of smoking for mental health, our results suggest that current-heavy rather than ever-heavy smoking is a major determinant of MD risk and point towards the benefits of smoking cessation maintenance.

Cigarette smoking and its relationship to mood disorder symptoms and co-occurring alcohol and cannabis use disorders following first hospitalization for bipolar disorder

OBJECTIVES

Cigarette smoking is highly prevalent among individuals with bipolar disorder (BD) and may adversely affect symptoms of the disorder, as well as the co-occurrence of other substance use disorders. However, anecdotal reports suggesting that smoking cessation caused a worsening of mood in smokers with BD have raised concerns about quitting. In the present study, we prospectively evaluated the course of BD, alcohol use disorders, and cannabis use disorders in relation to smoking and examined the relationship between smoking abstinence and changes in mood.

METHODS

Participants (N = 161) were adolescents (n=80) and adults (n = 81) with bipolar I disorder who were hospitalized for their initial mixed or manic episode. Participants were followed up to eight years post-hospitalization (median follow-up = 122 weeks) as part of a naturalistic, observational study of the longitudinal course of BD and substance use.

RESULTS

The course of BD symptoms in the 12 months following index hospitalization did not differ by smoking status in either the adolescent or the adult subsample. Among adolescents, smoking was associated with an increased risk of having a cannabis or alcohol use disorder, almost all of which were new-onset disorders, in the year following first hospitalization. Neither adolescents nor adults who were abstinent from smoking for at least two months experienced significant increases in depressive or manic symptoms.

CONCLUSIONS

Although cigarette smoking did not predict a worse course of BD, smoking was associated with an increased risk of developing alcohol and cannabis use disorders in adolescents with BD. Importantly, these data provide no evidence to suggest that abstinence from smoking is associated with worsening symptoms of depression or mania in the short term.

Oral Nicotine Self-Administration in Rodents

Nicotine addiction is a complex process that begins with self-administration. Consequently, this process has been studied extensively using animal models. A person is usually not called "smoker" if s/he has smoked for a week or a month in a lifetime; in general, a smoker has been smoking for many years. Furthermore, a smoker has free access to cigarettes and can smoke whenever she/he wants, provided there are no social/legal restraints. Subsequently, in an animal model of tobacco addiction, it will be desirable to expose the animal to free access nicotine for 24 hours/day for many weeks, starting at different stages of development.

Neighborhood perceptions are associated with tobacco dependence among African American smokers

INTRODUCTION

The animal and human research literatures suggest that deprived environmental conditions may be associated with drug dependence, but the relation of neighborhood perceptions with a multidimensional measure of tobacco dependence has not been previously studied. The purpose of this study was to examine the associations between neighborhood perceptions (neighborhood problems and neighborhood vigilance) and tobacco dependence among smokers as measured by the Wisconsin Inventory of Smoking Dependence Motives-68 (WISDM).

METHODS

Participants were 384 African American smokers (49% men, 80% < $30,000 annual household income) enrolled in a randomized clinical trial of a smoking cessation intervention. A series of regression models were conducted to examine the associations between neighborhood perceptions and tobacco dependence using a generalized estimating equation approach, which accounted for potential correlation in tobacco dependence between participants from the same neighborhood.

RESULTS

Results indicated that more self-reported neighborhood problems and greater neighborhood vigilance were significantly associated with tobacco dependence as measured by the WISDM total score in analyses adjusted for age, gender, income, education, employment status, and partner status (p ≤ .002). Neighborhood perceptions were related to both primary and secondary dependence motives (p ≤ .005).

CONCLUSIONS

Results suggest that the neighborhood context is associated with dependence on tobacco among African American smokers but longitudinal studies are needed to assess causation. Future research should also explore the mechanisms that account for the associations between neighborhood perceptions and tobacco dependence to better inform intervention development.

Major depression is a risk factor for shorter time to first cigarette irrespective of the number of cigarettes smoked per day: evidence from a National Population Health Survey

Introduction:

We assessed whether major depression (MD) predicts progression of nicotine dependence (ND) as measured by reduction in the time to first cigarette (TTFC) after waking and the roles of the number of cigarettes smoked per day (CPD) and stress as explanatory variables of this association.

Methods:

Ten years of follow-up data from the National Population Health Survey (NPHS) were used. The analyses were based on this nationally representative sample of the Canadian population who were over the age of 12 years in 1996 (n = 13,298). The NPHS included measures of MD and TTFC. Shorter TTFC was defined as TTFC within 5 min of waking. Heavy smoking (HS) was defined by smoking 20 or more CPD. Using proportional hazard models, unadjusted and adjusted hazard ratios (HRs) for shorter TTFC were estimated for those with and without MD.

Results:

The unadjusted HR for shorter TTFC among those with MD versus those without MD was 3.7 (95% CI: 2.6–5.3, p < .001). MD predicted onset of shorter TTFC even after adjustment for HS and tendency to smoke more under stress (HR: 1.7; 95% CI: 1.1–2.5, p = .02). When TTFC was defined using longer cutoffs (30 and 60 min), HS completely accounted for the effect of MD on TTFC onset.

Conclusions:

MD appears to be a risk factor for transition to shorter TTFC independent of effects of HS and the tendency to smoke more under stress. As MD is often modifiable, the above association points toward a preventive opportunity in relation to worsening of ND.

Self-efficacy mediates the effect of depression on smoking susceptibility in adolescents

INTRODUCTION

Research indicates that negative affect and/or depression is associated with increased prevalence for smoking and higher levels of nicotine dependence in adults and adolescents. A previous study with adult smokers attempting to quit indicated that low levels of self-efficacy partially mediated depression's adverse effect on posttreatment cessation.

METHOD

The current study attempted to test self-efficacy as a potential mediator between depressive symptoms and smoking susceptibility in adolescents. One thousand and ninety-three nonsmoking high-school students who were part of a large clinical trial evaluating an interactive CD-ROM-based smoking prevention/cessation curriculum (project ASPIRE) were included in this analysis. These students completed an extensive battery before treatment and 18 months after treatment, which included measures of depression, self-efficacy, smoking status, and smoking susceptibility.

RESULTS

Results indicated that self-efficacy partially mediated the positive relationship between baseline depressive symptoms and susceptibility to smoke at 18 months, accounting for approximately 27% of the variance.

CONCLUSIONS

Perhaps future interventions to prevent smoking in adolescents can target self-efficacy potentially resulting in more effective outcomes, particularly in adolescents with current depressive symptoms or who may be at risk for future depression.

Adolescent mental health as a risk factor for adolescent smoking onset

Smoking continues to be a leading cause of preventable deaths and rates of trying cigarettes and progression to daily smoking among adolescents continues to remain high. A plethora of risk factors for smoking among adolescents has been addressed in the research literature. One that is gaining particular interest is the relationship between adolescent mental health and smoking (both initiation and progression). This paper reviews the evidence for adolescent mental health as a risk factor for cigarette smoking. We focus on the specific mental health conditions that have been more thoroughly addressed as possible risk factors in community-dwelling adolescents. We discuss the multiple hypotheses that have been posited as to the nature of the relationship between adolescent mental health and smoking, as well as detailing so called third factors that may account for the observed relationship. We highlight the contribution of the existing studies to the body of knowledge on this topic, as well as the limitations and open questions that remain as a result. We conclude with discussion of a broad research agenda going forward.

A population-based twin study of the genetic and environmental relationship of major depression, regular tobacco use and nicotine dependence

BACKGROUND

Numerous epidemiological studies have reported a positive association between major depression (MD) and regular tobacco use (RU) or nicotine dependence (ND). However, few have used a genetically informative design to assess whether these traits share a common genetic and/or environmental liability.

METHOD

We assessed MD, RU and ND in same-sex twins from the population-based Swedish Twin Registry. In males, we examined both cigarette use and snus (smokeless tobacco) use. We used structural equation modeling to examine the relationship between MD, RU, and ND given RU.

RESULTS

The results suggest modest correlations between MD and RU, and between MD and ND. In males, the liability shared between MD and RU is solely genetic for both cigarettes and snus, while MD and ND share both genetic and unique environmental influences. The continuation to ND given RU differed considerably between cigarette and snus users. In females, both MD-RU and MD-ND relationships are partially attributable to genetic and unique environmental correlations.

CONCLUSIONS

The relationship among MD, RU and ND is at least partially attributable to shared genetic and environmental risk factors. The genetic and environmental correlations between traits are modest. The nature of the shared liability differs by sex, and in males, by the type of tobacco product used. Differences between previous reports and results presented in the current study are suggestive of population differences in how MD and tobacco use inter-relate.

Interactions between endocannabinoid and serotonergic systems in mood disorders caused by nicotine withdrawal

INTRODUCTION

Endocannabinoid and serotonin systems are implicated in mechanisms underlying depression-like symptoms. Involvement of serotonin in mood disorders occurring after smoking cessation has been observed. We studied the interactions between endocannabinoid and serotonergic systems in mood and behavioral disorders caused by nicotine cessation. The effects of the endocannabinoid transport inhibitor AM404 and the cannabinoid receptor 1 antagonist AM251 in a nicotine-dependent rodent model were investigated.

METHODS

Dependence was induced by subcutaneous injections of nicotine (2 mg/kg, 4 injections daily) for 15 consecutive days in mice. Animals treated with AM404 or AM251 were tested for locomotor activity and abstinence signs 24 hr after nicotine withdrawal and in forced swimming test (FST) at different times: immediately after last nicotine injection (t = 0) and 15 and 30 days after nicotine withdrawal. In nicotine-dependent mice treated with AM404 or AM251, expression of diencephalic serotonin receptor 1(A) (5-HT1(A)) was also measured. Effects of AM404, AM251, and WAY 100635 (5-HT(1A) receptor antagonist) in mice subjected to FST were evaluated.

RESULTS

A decrease in diencephalic 5-HT(1A) levels was observed in mice previously injected with nicotine. In the same animals, AM251 caused (0.5-2 mg/kg) a significant decrease of abstinence signs and AM404 (0.5-2 mg/kg) provoked a significant dose-dependent reduction in immobility time in the FST. Either AM251 or WAY 100635 antagonized anti-immobility effects of AM404.

CONCLUSIONS

Data indicate the existence of a link between serotonergic and endocannabinoid systems in the mechanisms underlying mood disorders caused by nicotine abstinence and suggest that these interactions are potential targets for pharmacological aid in smoking cessation.

The co-occurrence of cigarette smoking and bipolar disorder: phenomenology and treatment considerations

OBJECTIVES

  Despite recent advances in understanding the causes and treatment of nicotine dependence among individuals with psychiatric disorders, smoking among individuals with bipolar disorder (BD) has received little attention. The goal of this review is to synthesize the literature on the epidemiology, consequences, and treatment of smoking and nicotine dependence among individuals with BD and to delineate a future research agenda.

METHODS

  We conducted a PubMed search of English-language articles using the search terms bipolar disorder, mania, tobacco, nicotine, and smoking, followed by a manual search of the literature cited in the identified articles. Articles were chosen by the authors on the basis of their relevance to the topic areas covered in this selective review.

RESULTS

  Adults with BD are two to three times more likely to have started smoking and, on the basis of epidemiological data, may be less likely to initiate and/or maintain smoking abstinence than individuals without psychiatric disorders. Smoking cessation is achievable for individuals with BD, but challenges such as chronic mood dysregulation, high prevalence of alcohol and drug use, more severe nicotine dependence, and limited social support can make quitting more difficult. Effective treatments for tobacco cessation are available, but no controlled trials in smokers with BD have been conducted.

CONCLUSIONS

  Cigarette smoking is a prevalent and devastating addiction among individuals with BD and should be addressed by mental health providers. Additional research on the mechanisms of, and optimal treatment for, smoking and nicotine dependence in this population is desperately needed.