Prevalence of Cigarette Smoking and Nicotine Dependence in Men and Women Residing in Two Provinces in China

Integrative analysis of genetics, epigenetics and RNA expression data reveal three susceptibility loci for smoking behavior in Chinese Han population

Despite numerous studies demonstrate that genetics and epigenetics factors play important roles on smoking behavior, our understanding of their functional relevance and coordinated regulation remains largely unknown. Here we present a multiomics study on smoking behavior for Chinese smoker population with the goal of not only identifying smoking-associated functional variants but also deciphering the pathogenesis and mechanism underlying smoking behavior in this under-studied ethnic population. After whole-genome sequencing analysis of 1329 Chinese Han male samples in discovery phase and OpenArray analysis of 3744 samples in replication phase, we discovered that three novel variants located near FOXP1 (rs7635815), and between DGCR6 and PRODH (rs796774020), and in ARVCF (rs148582811) were significantly associated with smoking behavior. Subsequently cis-mQTL and cis-eQTL analysis indicated that these variants correlated significantly with the differential methylation regions (DMRs) or differential expressed genes (DEGs) located in the regions where these variants present. Finally, our in silico multiomics analysis revealed several hub genes, like DRD2, PTPRD, FOXP1, COMT, CTNNAP2, to be synergistic regulated each other in the etiology of smoking.

Identification and validation of a novel gene ARVCF associated with alcohol dependence among Chinese population

Alcohol dependence is a heritable disorder, yet its genetic basis and underlying mechanisms remain poorly understood, especially in Chinese population. In this study, we conducted gene-based and transcript-based association tests and found a significant association between ARVCF expression in the cortex and hippocampus of the brain and alcohol use in a cohort of 1,329 individuals with Chinese ancestry. Further analysis using the effective-median-based Mendelian randomization framework for inferring the causal genes (EMIC) revealed a causal relationship between ARVCF expression in the frontal cortex and alcohol use. Moreover, leveraging extensive European alcohol dependence data, our gene association tests and EMIC analysis showed that ARVCF expression in the nucleus accumbens was significantly associated with alcohol dependence. Finally, animal studies indicated that Arvcf knockout mice lacked conditioned place preference for alcohol. Together, our combined human genetic and animal studies indicate that ARVCF plays a crucial role in alcohol dependence.

Smoking prevalence among adults in China Mainland and their age of smoking initiation during adolescence: a national cross-sectional study

OBJECTIVES

This study aims to calculate the national prevalence of smoking among Chinese adults and to describe the hazard of smoking initiation by age during their adolescence, as well as the disparities in sex, residence and age groups.

DESIGN

A cross-sectional study.

SETTING

The data were derived from a multistage sampling study conducted in 120 cities in China Mainland.

PARTICIPANTS

A total of 9963 participants aged ≥19 years were included.

PRIMARY OUTCOME MEASURES

Survival analysis was used to quantify the hazards of smoking initiation by a single year of age during adolescence, and the log-rank test was used to compare the hazard curves across subgroups.

RESULTS

The prevalence of current smoking among males and females was 27.7% and 2.0%, respectively, and 56.2% of current smokers began smoking at or before the age of 18. The hazard of smoking initiation during adolescence for females was less than 0.5%, and the hazard for males increased gradually before 14 years of age and increased sharply at age 15 (4.34%), then peaked at age 18 (6.24%). Males in rural experienced a higher hazard of smoking initiation than those in urban (χ2=5.35, p=0.02) and no such difference was found in females. By the age of 18 years, 11.7% of participants (1.8% for females and 23.4% for males) had ever smoked.

CONCLUSIONS

The prevalence of smoking among Chinese adults was lower than once reported. Males experienced higher hazards of smoking initiation at all ages than females. The hazard pattern suggests that the key focus for smoking prevention are males and adolescents aged 15-18 years, and future interventions should be delivered to the right target population at the appropriate time.

Prevalence of nicotine dependence among smokers aged 40 years and older in China

Background

Nicotine dependence, also known as tobacco dependence, is a common chronic disease and a major risk factor for chronic respiratory diseases. The present study was designed to determine the prevalence of nicotine dependence and its changes among smokers aged 40 years and older in China, to analyze the characteristics of nicotine dependence among smokers, and to provide a reference for smoking cessation interventions.

Methods

The data were sourced from nationally representative large-sample surveys conducted during 2014-2015 and 2019-2020 in the Chinese population, covering 125 counties (districts) in 31 provinces, autonomous regions and municipalities. Variables related to smoking and nicotine dependence among residents ≥40 years old were collected in face-to-face interviews. A total of 20,062 and 18,975 daily smokers were included in the 2014-2015 and 2019-2020 surveys, respectively. The severity of nicotine dependence was evaluated according to the Fagerström Test for Nicotine Dependence and Heaviness of Smoking Index. The level and change in nicotine dependence among daily smokers aged ≥40 years were estimated using a complex weighted sampling design, and their influencing factors were analyzed.

Results

Levels of nicotine dependence among daily smokers aged ≥40 years in China could be divided into very low, low, medium, high, and very high, accounting for 31.1%, 27.9%, 13.4%, 20.5%, and 7.1% of the total, respectively. The average Fagerström Test for Nicotine Dependence score was 3.9 (95% confidence interval [CI]: 3.8-4.0), with the prevalence of medium-high nicotine dependence being 41.0% (95% CI: 39.0-42.9%) and that of high and very high nicotine dependence being 27.6% (95% CI: 26.0-29.3%), both of which were significantly higher in men than in women (both P < 0.001). Among daily smokers, those with a low education level, age at smoking initiation <18 years, and with smoking duration of ≥20 years had a higher degree of nicotine dependence. In terms of geographic region, the level of medium-high nicotine dependence in South China was higher than in other areas, and the decline in the prevalence of high nicotine dependence was the greatest in Northwest China (P < 0.001). The prevalence of medium-high and high and very high nicotine dependence was significantly higher in men with chronic respiratory symptoms, chronic obstructive pulmonary disease (COPD), and/or chronic respiratory diseases than in men without these conditions (all P < 0.05). The prevalence of high and very high nicotine dependence in women with chronic respiratory symptoms and chronic respiratory diseases was significantly higher than that in women without these conditions (both P < 0.05). Compared with that during 2014-2015, the prevalence of high nicotine dependence among daily smokers decreased during 2019-2020 by 4.5 percentage points in the total population (P < 0.001) and by 4.8 percentage points in men (P < 0.001), with no significant change seen in women (P > 0.05). Additionally, the prevalence of high nicotine dependence in men with chronic respiratory symptoms and COPD decreased by 6.7 and 4.7 percentage points, respectively (P < 0.05), but showed no significant change in women with these conditions (P > 0.05). Multivariate logistic regression analysis showed that the risk of medium-high nicotine dependence was higher among daily smokers who were male; 50-59 years old; unmarried/divorced/widowed/separated; engaged in agriculture, forestry, husbandry, fishery and water conservancy; had a low education level; started smoking before the age of 18 years; and smoked for more than 20 years.

Conclusions

The past few years have seen a slight decline in the prevalence of high (severe) nicotine dependence among smokers aged ≥40 years in China. However, 41.0% of daily smokers had medium-high nicotine dependence, and 27.6% had high or very high nicotine dependence, with notable differences in population and geographic distributions. Development of tailored interventions, optimization of smoking cessation service systems, and integration of smoking cessation into the management of chronic diseases will effectively reduce the burden of nicotine dependence in China.

Association of cigarette smoking with cerebrospinal fluid biomarkers of insulin sensitivity and neurodegeneration

INTRODUCTION

Cigarette smoking increases both the risk for insulin resistance and amyloid-β (Aβ) aggregation, and impaired brain insulin/insulin-like growth factor 1 (IGF1) signaling might increase risk factors for Alzheimer's disease (AD). We aimed to investigate the association among cerebrospinal fluid (CSF) insulin sensitivity/IGF1, glucose/lactate, and Aβ42 and further explore whether insulin sensitivity contributed to the risk for AD in active smokers.

METHODS

In this cross-sectional study, levels of insulin, IGF1, and lactate/glucose of 75 active smokers and 78 nonsmokers in CSF were measured. Three polymorphisms regulating IGF1 were genotyped. Analysis of variance was used to compare differences of variables between groups. Partial correlation was performed to test the relationship between CSF biomarkers and smoking status. General linear models were applied to test the interaction of the effect of single nucleotide polymorphisms and cigarette smoking on CSF IGF1 levels.

RESULTS

In the CSF from active smokers, IGF1 and lactate levels were significantly lower (p = .016 and p = .010, respectively), whereas Aβ42 (derived from our earlier research) and insulin levels were significantly higher (p < .001 and p = .022, respectively) as compared to the CSF from nonsmokers. The AG + GG genotype of rs6218 in active smokers had a significant effect on lower CSF IGF1 levels (p = .004) and lower CSF insulin levels in nonsmokers (p = .016).

CONCLUSIONS

Cigarette smoking as the "at-risk" factor for AD might be due to lower cerebral insulin sensitivity in CSF, and the subjects with rs6218G allele seem to be more susceptible to the neurodegenerative risks for cigarette smoking.

Single nucleotide polymorphisms rs148582811 regulates its host gene ARVCF expression to affect nicotine-associated hippocampus-dependent memory

Although numerous susceptibility loci are nominated for nicotine dependence (ND), no report showed any association of ARVCF with ND. Through genome-wide sequencing analysis, we first identified genetic variants associated nominally with ND and then replicated them in an independent sample. Of the six replicated variants, rs148582811 in ARVCF located in the enhancer-associated marker peak is attractive. The effective-median-based Mendelian randomization analysis indicated that ARVCF is a causal gene for ND. RNA-seq analysis detected decreased ARVCF expression in smokers compared to nonsmokers. Luciferase reporter assays indicated that rs148582811 and its located DNA fragment allele-specifically regulated ARVCF expression. Immunoprecipitation analysis revealed that transcription factor X-ray repair cross-complementing protein 5 (XRCC5) bound to the DNA fragment containing rs148582811 and allele-specifically regulated ARVCF expression at the mRNA and protein levels. With the Arvcf knockout mouse model, we showed that Arvcf deletion not only impairs hippocampus-dependent learning and memory, but also alleviated nicotine-induced memory deficits.

Analysis of nicotine dependence among daily smokers in China: evidence from a cross-sectional study in Zhejiang Province

OBJECTIVE

The current study aimed to assess the level of nicotine dependence and its influencing factors among daily smokers in Zhejiang, China.

SETTING

The 2020 Global Adult Tobacco Survey was conducted in Zhejiang, China.

PARTICIPANTS

1244 daily smokers aged ≥15 years.

MEASURES

Respondents were asked questions regarding their age, sex, residence, education level, occupation, household income, age of starting daily smoking and nicotine dependence.

RESULTS

The findings revealed that 17.4% of daily smokers were highly dependent on nicotine, and the mean Fagerström Test for Nicotine Dependence score of daily smokers was (3.1±2.4). Age, educational level, occupation and age of starting daily smoking had significant effects on high nicotine dependence, whereas residence, sex and yearly household income were not significant factors. Compared with the age group ≥60 years, the proportion of respondents with a higher nicotine dependence level was lower in the age group of 15-39 years (OR=0.45). Daily smokers with a higher education level had a lower nicotine dependence level than those with a lower education level: primary or less (OR=3.07) and secondary (OR=2.62). Government institution staff (OR=4.02), unemployed persons (OR=3.08) and industrial workers (OR=2.46) had significantly higher nicotine dependence levels than did workers in the other occupation categories. People who started daily smoking at ≤18 years of age had a higher nicotine dependence level (OR=2.25) than those who started later.

CONCLUSIONS

This study elucidated that nearly one-fifth of daily smokers in Zhejiang, China, have high nicotine dependence levels. Improved health information on tobacco smoking is needed to encourage daily smokers to quit smoking, particularly among young males, unemployed persons and those with lower education levels.

Metal ions in cerebrospinal fluid: Associations with anxiety, depression, and insomnia among cigarette smokers

OBJECTIVE

The study aimed to investigate the relationship between cerebrospinal fluid (CSF) metal ions and anxiety, depression, and insomnia among cigarette smokers.

METHODS

We measured CSF levels of various metal ions from 178 Chinese male subjects. Apart from sociodemographic and clinical characteristics data, the Fagerstrom Test for Nicotine Dependence (FTND), Beck Depression Inventory (BDI), Self-Rating Anxiety Scale (SAS), and Pittsburgh Sleep Quality Index (PSQI) were applied.

RESULTS

BDI and PSQI scores (all p < 0.001) were significantly higher in active smokers than nonsmokers. Active smokers have significantly higher CSF levels of magnesium, zinc, iron, lead, lithium, and aluminum (all p ≤ 0.002). Some metal ions, including zinc, iron, lead, and aluminum, were found to have a significant correlation with BDI scores, whereas metal ions, including zinc and lead, were found to have a significant correlation with PSQI scores in the general group. More interesting, mediation analysis showed that aluminum mediated the relationship between smoking and depression.

CONCLUSIONS

Cigarette smoking was indeed associated with depression and insomnia. Active smokers had significantly higher CSF levels of magnesium, zinc, iron, lead, lithium, and aluminum. Furthermore, CSF aluminum played a mediating role in the relationship between smoking and depression, which further confirmed its neurotoxicity.

Prevalence of tobacco dependence and associated factors in China: Findings from nationwide China Health Literacy Survey during 2018-19

Background

Tobacco dependence is the key barrier to successful smoking cessation. However, little is known about its prevalence, sociodemographic characteristics and determinants. We aimed to estimate the prevalence, associated factors and burden of tobacco dependence in China.

Methods

During 2018-2019, the nationally representative 2018 China Health Literacy Survey (2018 CHLS) invited 87,708 participants to participate using a multistage stratified sampling method from 31 provinces (or equivalent) in mainland China, and 84,839 participants aged 20-69 with valid data were included in the analysis. We diagnosed tobacco dependence based on international criteria (ICD-10, DSM-4) and tailored to Chinese population according to China Clinical Guideline for Tobacco Cessation (2015 version). The prevalence of tobacco dependence was estimated overall and by sociodemographic factors. The Logistic regression was conducted to estimate odds ratios (OR) and 95% confidence intervals (CIs) for tobacco dependence and success of smoking cessation (being ex-smokers), with different levels of adjustment. These were used to estimate the total number of adults who were tobacco dependent in China.

Findings

In China, the estimated prevalence of current smoking was 25.1%, significantly higher in men than in women (47.6% vs 1.9%). The prevalence of current smoking varied approximately 3-fold (12.9% to 37.9%) across 31 provinces of China. Among general population aged 20-69 years, the prevalence of tobacco dependence was 13.1% (95% CI:12.2-14.1). Among current smokers, the prevalence of tobacco dependence was 49.7% (46.5-52.9%), with no difference between men and women (49.7% vs 50.8%). The prevalence of tobacco dependence was associated significantly with smoking intensity, defined by pack-years (1.62 [1.54-1.70] per 10 pack-years), cigarettes smoked per day (2.01 [1.78, 2.27] per 10 cigarettes), and smoking starting age (0.93 [0.90, 0.97] per 5 years). Given smoking intensity, the prevalence of tobacco dependence also varied by age, gender, certain socioeconomic status and regions. Compared with those without tobacco dependence, ever smokers with tobacco dependence were less likely to be ex-smokers (2.88, 2.59-3.21). In China, 183.5 (170.4-197.4) million adults (177.5 million were men) were tobacco dependent in 2018.

Interpretation

In China, tobacco dependence is highly prevalent, with approximately half of current smokers being addictive, highlighting the need for coordinated effort to improve awareness, diagnosis and treatment of tobacco dependence.

Funding

Chinese Academy of Medical Sciences (CAMS) Initiative for Innovative Medicine (CAMS 2021-I2M-1-010), National Key R&D Program of China (grant no 2017YFC1309400), and National Natural Science Foundation of China (grant no 81720108001).

Note

Chinese translation of abstract is available in appendix section.

Nicotine dependence and quitting stages of smokers in Nepal: A community based cross-sectional study

INTRODUCTION

Nicotine dependence is an addiction to tobacco products caused by the chemical nicotine present in tobacco. 80% of premature deaths due to nicotine dependence come from low-and middle-income countries. Since most of the public health studies have focused solely on psychological and behavioral factors associated with tobacco smoking, this study aims to assess the nicotine dependence and stages of change of quitting smoking.

METHODOLOGY

A community based quantitative cross-sectional study was conducted among 280 smokers aged 15-69 years in Bharatpur metropolitan, Nepal. A semi-structured and validated questionnaire was used during the face-to-face interviews. Nicotine dependence among participants was assessed using the six-item Fagerstrom Test for Nicotine Dependence (FTND). Chi-square test and multivariate logistic regression analysis were performed to assess the associations between variables at the significance level α = 0.05.

RESULT

In the study population, the mean score of FTND was 5.15 ± 2.34. 33.9% participants had a high level of nicotine dependence and nearly half of the participants felt difficulty to refrain smoking even in No-smoking areas. Almost three out of ten respondents were prepared for smoking cessation. It was found that age group 20-39 years were more likely to have nicotine dependence (AOR 3.308, 95% CI = 1.039-10.534), those who initiated smoking before age of 15 were associated with a greater risk of nicotine dependence (AOR 3.68, 95% CI = 1.826-7.446), participants spending more on tobacco products (more than Rs 2400 monthly) were associated with an increased risk of nicotine dependence (AOR 4.47, 95% CI = 2.225-8.991), those who initiated smoking due to mental stress were more likely to have nicotine addiction (AOR 2.522, 95% CI = 1.004-6.028), and those who had no thought of quitting smoking were more associated with nicotine dependence (AOR 4.935, 95% CI = 1.458-16.699).

CONCLUSION

Our study showed that high level of nicotine dependence is a major public health problem in low-and middle-income countries like Nepal. It also highlights that effective smoking cessation programs should be developed considering the level of nicotine dependence with more focus on early interventions of its associated factors.

Genome-wide methylation and expression analyses reveal the epigenetic landscape of immune-related diseases for tobacco smoking

BACKGROUND

Smoking is a major causal risk factor for lung cancer, chronic obstructive pulmonary disease (COPD), cardiovascular disease (CVD), and is the main preventable cause of deaths in the world. The components of cigarette smoke are involved in immune and inflammatory processes, which may increase the prevalence of cigarette smoke-related diseases. However, the underlying molecular mechanisms linking smoking and diseases have not been well explored. This study was aimed to depict a global map of DNA methylation and gene expression changes induced by tobacco smoking and to explore the molecular mechanisms between smoking and human diseases through whole-genome bisulfite sequencing (WGBS) and RNA-sequencing (RNA-seq).

RESULTS

We performed WGBS on 72 samples (36 smokers and 36 nonsmokers) and RNA-seq on 75 samples (38 smokers and 37 nonsmokers), and cytokine immunoassay on plasma from 22 males (9 smokers and 13 nonsmokers) who were recruited from the city of Jincheng in China. By comparing the data of the two groups, we discovered a genome-wide methylation landscape of differentially methylated regions (DMRs) associated with smoking. Functional enrichment analyses revealed that both smoking-related hyper-DMR genes (DMGs) and hypo-DMGs were related to synapse-related pathways, whereas the hypo-DMGs were specifically related to cancer and addiction. The differentially expressed genes (DEGs) revealed by RNA-seq analysis were significantly enriched in the "immunosuppression" pathway. Correlation analysis of DMRs with their corresponding gene expression showed that genes affected by tobacco smoking were mostly related to immune system diseases. Finally, by comparing cytokine concentrations between smokers and nonsmokers, we found that vascular endothelial growth factor (VEGF) was significantly upregulated in smokers.

CONCLUSIONS

In sum, we found that smoking-induced DMRs have different distribution patterns in hypermethylated and hypomethylated areas between smokers and nonsmokers. We further identified and verified smoking-related DMGs and DEGs through multi-omics integration analysis of DNA methylome and transcriptome data. These findings provide us a comprehensive genomic map of the molecular changes induced by smoking which would enhance our understanding of the harms of smoking and its relationship with diseases.

National, regional, and global prevalence of cigarette smoking among women/females in the general population: a systematic review and meta-analysis

Background

This systematic and meta-analysis review aimed to provide an updated estimate of the prevalence of ever and current cigarette smoking in women, in geographic areas worldwide, and demonstrate a trend of the prevalence of smoking over time by using a cumulative meta-analysis.

Methods

Following PRISMA guidelines, we conducted a systematic review and meta-analysis of studies published on the prevalence of ever and current cigarette smoking in women. We searched PubMed, Web of Science (ISI), Scopus, and Ovid from January 2010 to April 2020. The reference lists of the studies included in this review were also screened. Data were reviewed and extracted independently by two authors. A random effects model was used to estimate the pooled prevalence of ever and current cigarette smoking in women. Sources of heterogeneity among the studies were determined using subgroup analysis and meta-regression.

Results

The pooled prevalence of ever and current cigarette smoking in women was 28% and 17%, respectively. The pooled prevalence of ever cigarette smoking in adolescent girls/students of the school, adult women, pregnant women, and women with the disease was 23%, 27%, 32%, and 38%, respectively. The pooled prevalence of ever cigarette smoking in the continents of Oceania, Asia, Europe, America, and Africa was 36%, 14%, 38%, 31%, and 32%, respectively.

Conclusions

The prevalence of cigarette smoking among women is very high, which is significant in all subgroups of adolescents, adults, and pregnant women. Therefore, it is necessary to design and implement appropriate educational programs for them, especially in schools, to reduce the side effects and prevalence of smoking among women.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12199-020-00924-y.

Feasibility and Acceptability of a Cognitive Behavioral Therapy-Based Smartphone App for Smoking Cessation in China: A Single-Group Cohort Study

BACKGROUND

Previous research has suggested that mobile phone applications (apps) may potentially increase quit rates. The purpose of this single-group cohort study sought to examine the feasibility and acceptability of a novel smartphone-based smoking cessation app designed for smoking cessation in China: smoking quit rate.

METHODS

A total of 180 smokers from two cities of mainland China with willingness to make a quit attempt were invited to this smoking cessation app program, a cognitive behavioral theory (CBT)-based smoking cessation intervention via a smartphone app. Participants received 37- to 44-day intervention (including 7- to 14-day pre-quit preparation and 33-day intervention from quit date). Feasibility and acceptability of the program, and smoking status were assessed at baseline stage (initial installation), pre-quit stage, and post-quit stage (days 7, 15, and 33 after quit date).

RESULTS

A total of 163 (90.6%) participants completed the study. Among them, 76-89% of the participants logged into the app ≥1 time per day across stages (at baseline, during pre-quit stage, and on days 7, 15, and 33 of post-quit stage); approximately 90% of the participants were satisfied with the app across stages. A significant rise in self-reported overall satisfaction with the app is observed from baseline (93% at Time 1) to the end of the program (98% at Time 2, 33 days after quit date) (p = 0.021). Participants who believed/agreed this app can help them to quit smoking significantly increased from 69% at baseline to 97% at day 33 after quit date (p < 0.001). Participants were satisfied with most (80-90%) of the features, especially the information feature. Intention-to-treat analysis showed that the percentage of 33-day self-reported continuous prevalence abstinence was 63.9%, and 7-day point prevalence abstinence rate was 81.7, 87.2, and 77.8% on days 7, 15, and 33 after quit date, respectively.

CONCLUSIONS

This study demonstrated the feasibility and acceptability of the smartphone app intervention for smoking cessation and introduced a new digital treatment model, which is expected to overcome barriers facing accessing traditional in-person smoking cessation services and extend nationwide smoking cessation services in China.

Genetic and Epigenetic Analysis Revealing Variants in the NCAM1-TTC12-ANKK1-DRD2 Cluster Associated Significantly With Nicotine Dependence in Chinese Han Smokers

BACKGROUNDS

Although studies have demonstrated that the NCAM1-TTC12-ANKK1-DRD2 gene cluster plays essential roles in addictions in subjects of European and African origin, study of Chinese Han subjects is limited. Further, the underlying biological mechanisms of detected associations are largely unknown.

METHODS

Sixty-four single-nucleotide polymorphisms (SNPs) in this cluster were analyzed for association with Fagerstrőm Test for Nicotine Dependence score (FTND) and cigarettes per day (CPD) in male Chinese Han smokers (N = 2616). Next-generation bisulfite sequencing was used to discover smoking-associated differentially methylated regions (DMRs). Both cis-eQTL and cis-mQTL analyses were applied to assess the cis-regulatory effects of these risk SNPs.

RESULTS

Association analysis revealed that rs4648317 was significantly associated with FTND and CPD (p = .00018; p = .00072). Moreover, 14 additional SNPs were marginally significantly associated with FTND or CPD (p = .05-.01). Haplotype-based association analysis showed that one haplotype in DRD2, C-T-A-G, formed by rs4245148, rs4581480, rs4648317, and rs11214613, was significantly associated with CPD (p = .0005) and marginally associated with FTND (p = .003). Further, we identified four significant smoking-associated DMRs, three of which are located in the DRD2/ANKK1 region (p = .0012-.00005). Finally, we found five significant CpG-SNP pairs (p = 7.9 × 10-9-6.6 × 10-6) formed by risk SNPs rs4648317, rs11604671, and rs2734849 and three methylation loci.

CONCLUSIONS

We found two missense variants (rs11604671; rs2734849) and an intronic variant (rs4648317) with significant effects on ND and further explored their mechanisms of action through expression and methylation analysis. We found the majority of smoking-related DMRs are located in the ANKK1/DRD2 region, indicating a likely causative relation between non-synonymous SNPs and DMRs.

IMPLICATIONS

This study shows that there exist significant association of variants and haplotypes in ANKK1/DRD2 region with ND in Chinese male smokers. Further, this study also shows that DNA methylation plays an important role in mediating such associations.

Association of Cigarette Smoking With Cerebrospinal Fluid Biomarkers of Neurodegeneration, Neuroinflammation, and Oxidation

IMPORTANCE

Cigarette smoking has been associated with risk of neurodegenerative disorders, such as Alzheimer disease. The association between smoking and biomarkers of changes in human cerebrospinal fluid (CSF) is not fully understood.

OBJECTIVE

To investigate the association of cigarette smoking with CSF biomarkers of neurodegeneration, neuroinflammation, oxidation, and neuroprotection.

DESIGN, SETTING, AND PARTICIPANTS

In this case-control study of 191 adult men in China, biomarkers in the CSF of participants with and without significant cigarette exposure were examined. Participants who did not smoke and had no history of substance use disorder or dependence were assigned to the nonsmoking group. The active smoking group included participants who consumed at least 10 cigarettes per day for 1 year. Five-milliliter samples of CSF were obtained from routine lumbar puncture conducted before anterior cruciate ligament reconstruction surgery. Data collection took place from September 2014 to January 2016, and analysis took place from January to February 2016.

EXPOSURES

Cigarette smoking.

MAIN OUTCOMES AND MEASURES

CSF levels of β-amyloid 42 (Aβ42), which has diagnostic specificity for Alzheimer disease, tumor necrosis factor alpha (TNFα), brain-derived neurotrophic factor (BDNF), total superoxide dismutase (SOD), and nitric oxide synthase (NOS) were measured. Sociodemographic data and history of smoking were obtained.

RESULTS

Of 191 participants, 87 (45.5%) were included in the active smoking group and 104 (54.4%) in the nonsmoking group. Compared with the active smoking group, the nonsmoking group was younger (mean [SD] age, 34.4 [10.5] years vs 29.6 [9.5] years; P = .01), had more education (mean [SD] duration of education, 11.9 [3.1] years vs 13.2 [2.6] years; P = .001), and had lower body mass index (mean [SD], 25.9 [3.6] vs 24.9 [4.0]; P = .005). Comparing the nonsmoking group with the smoking group, mean (SD) CSF levels of Aβ42 (38.0 [25.9] pg/mL vs 52.8 [16.5] pg/mL; P < .001) and TNFα (23.0 [2.5] pg/mL vs 28.0 [2.0] pg/mL; P < .001) were significantly lower, while BDNF (23.1 [3.9] pg/mL vs 13.8 [2.7] pg/mL; P < .001), total SOD (15.7 [2.6] U/L vs 13.9 [2.4] U/L; P < .001), total NOS (28.3 [7.2] U/L vs 14.7 [5.6] U/L; P < .001), inducible NOS (16.0 [5.4] U/L vs 10.3 [2.7] U/L; P < .001), and constitutive NOS (12.4 [6.9] U/mL vs 4.4 [3.9] U/mL) were higher. In addition, in participants in the smoking group who were aged 40 years or older, total SOD levels were negatively correlated with Aβ42 levels (r = -0.57; P = .02). In those who smoked at least 20 cigarettes per day, TNFα levels were positively correlated with Aβ42 levels (r = 0.51; P = .006). The association of TNFα with Aβ42 production was stronger than that of total SOD with Aβ42 production (z = -4.38; P < .001).

CONCLUSIONS AND RELEVANCE

This case-control study found that cigarette smoking was associated with at-risk biomarkers for Alzheimer disease, as indicated by higher Aβ42 levels, excessive oxidative stress, neuroinflammation, and impaired neuroprotection found in the CSF of participants in the active smoking group.

Active smoking, sleep quality and cerebrospinal fluid biomarkers of neuroinflammation

BACKGROUNDS

Cigarette smoking has been shown to be associated with sleep disorders and the related neuropathogenesis including neuroinflammation. Previous studies showed that pro- and anti-inflammatory cytokines are physiologically important in maintaining circadian function. In addition, sleep deprivation leads to immune dysregulations. However, no study has been published yet by using cerebrospinal fluid (CSF) biomarkers of neuroinflammation to investigate the relationship between active cigarette smoking and sleep disorders.

METHODS

CSF tissues from subjects of 191 male subjects (non-smokers n = 104; active smokers n = 87) receiving local anesthesia before surgery for anterior cruciate ligament injuries were obtained after the assessment of clinical information and Pittsburgh Sleep Quality Index (PSQI). The levels of tumor necrosis factor alpha (TNFα), Interleukin (IL) 1 beta (IL1β), IL2, IL4, IL6 and IL10 were measured using radioimmunoassay and ELISA.

RESULTS

PSQI scores were significantly higher in active smokers than that in non-smokers (p < 0.001, Cohen's d = 0.63). Significantly higher levels of CSF TNFα were found in active smokers compared to non-smokers (28 ± 1.97 vs. 22.97 ± 2.48, p < 0.05, Cohen's d = 2.23). There was a positive correlation between CSF IL1β levels and PSQI scores in non-smokers (r = 0.31, p = 0.01, adjustment R-Squared = 0.11).

DISCUSSION

This is the first study to reveal the association between higher CSF TNFα levels and poorer sleep quality in active smoking. In addition, CSF IL1β levels might be a potential biomarker in central nervous system for circadian dysregulation.

Expression of SARS-CoV-2 entry receptors in the respiratory tract of healthy individuals, smokers and asthmatics

SARS-CoV-2 is causing a pandemic with currently > 29 million confirmed cases and > 900,000 deaths worldwide. The locations and mechanisms of virus entry into the human respiratory tract are incompletely characterized. We analyzed publicly available RNA microarray datasets for SARS-CoV-2 entry receptors and cofactors ACE2, TMPRSS2, BSG (CD147) and FURIN. We found that ACE2 and TMPRSS2 are upregulated in the airways of smokers. In asthmatics, ACE2 tended to be downregulated in nasal epithelium, and TMPRSS2 was upregulated in the bronchi. Furthermore, respiratory epithelia were negative for ACE-2 and TMPRSS2 protein expression while positive for BSG and furin, suggesting a possible alternative entry route for SARS-CoV-2.

Genome-wide DNA methylation analysis reveals significant impact of long-term ambient air pollution exposure on biological functions related to mitochondria and immune response

Exposure to long-term ambient air pollution is believed to have adverse effects on human health. However, the mechanisms underlying these impacts are poorly understood. DNA methylation, a crucial epigenetic modification, is susceptible to environmental factors and likely involved in these processes. We conducted a whole-genome bisulfite sequencing study on 120 participants from a highly polluted region (HPR) and a less polluted region (LPR) in China, where the HPR had much higher concentrations of five air pollutants (PM_2.5, PM₁₀, SO₂, NO₂, and CO) (fold difference 1.6 to 6.6 times; P value 1.80E-07 to 3.19E-23). Genome-wide methylation analysis revealed 371 DMRs in subjects from the two areas and these DMRs were located primarily in gene regulatory elements such as promoters and enhancers. Gene enrichment analysis showed that DMR-related genes were significantly enriched in diseases related to pulmonary disorders and cancers and in biological processes related to mitochondrial assembly and cytokine production. Further, HPR participants showed a higher mtDNA copy number. Of those identified DMRs, 15 were significantly correlated with mtDNA copy number. Finally, cytokine assay indicated that an increased plasma interleukin-5 level was associated with greater air pollution. Taken together, our findings suggest that exposure to long-term ambient air pollution can lead to alterations in DNA methylation whose functions relate to mitochondria and immune responses.

Prediction of Smoking Behavior From Single Nucleotide Polymorphisms With Machine Learning Approaches

Smoking is a complex behavior with a heritability as high as 50%. Given such a large genetic contribution, it provides an opportunity to prevent those individuals who are susceptible to smoking dependence from ever starting to smoke by predicting their inherited predisposition with their genomic profiles. Although previous studies have identified many susceptibility variants for smoking, they have limited power to predict smoking behavior. We applied the support vector machine (SVM) and random forest (RF) methods to build prediction models for smoking behavior. We first used 1,431 smokers and 1,503 non-smokers of African origin for model building with a 10-fold cross-validation and then tested the prediction models on an independent dataset consisting of 213 smokers and 224 non-smokers. The SVM model with 500 top single nucleotide polymorphisms (SNPs) selected using logistic regression (p<0.01) as the feature selection method achieved an area under the curve (AUC) of 0.691, 0.721, and 0.720 for the training, test, and independent test samples, respectively. The RF model with 500 top SNPs selected using logistic regression (p<0.01) achieved AUCs of 0.671, 0.665, and 0.667 for the training, test, and independent test samples, respectively. Finally, we used the combined logistic (p<0.01) and LASSO (λ=10^-3) regression to select features and the SVM algorithm for model building. The SVM model with 500 top SNPs achieved AUCs of 0.756, 0.776, and 0.897 for the training, test, and independent test samples, respectively. We conclude that machine learning methods are promising means to build predictive models for smoking.

Association of Cigarette Smoking with Sleep Disturbance and Neurotransmitters in Cerebrospinal Fluid

BACKGROUND

Cigarette smoking has shown to be associated with sleep disturbance, especially prolonged sleep onset latency (SOL). Cigarette smoking stimulates the release of dopamine (DA) and serotonin (5-HT), which might promote awakening and inhibit rapid eye movement sleep. Dopamine transporter (DAT) and serotonin transporter play a key role in the reuptake of DA and 5-HT from the synaptic cleft into presynaptic neurons. However, the relationship among cigarette smoking, sleep disturbance and neurotransmitters has never been investigated in human cerebrospinal fluid (CSF).

METHODS

A total of 159 Chinese male subjects (81 active smokers and 78 non-smokers) who would undergo lumbar puncture before the surgery of anterior cruciate ligament reconstruction were recruited and 5mL-CSF samples were collected incidentally. CSF levels of DA, DAT, 5-HT, and serotonin transporter were measured using radioimmunoassay and ELISA. Sociodemographic data and the Pittsburgh Sleep Quality Index (PSQI) scale were collected before surgery.

RESULTS

PSQI global scores, SOL, and CSF DA levels were significantly higher in active smokers compared to non-smokers (2.00 [1.00-4.75] scores vs 4.00 [3.00-6.00] scores, p = 0.001; 10.00 [5.00-15.00] minutes vs 15.00 [10.00-30.00] minutes, p = 0.002; 87.20 [82.31-96.06]ng/mL vs 107.45 [92.78-114.38] ng/mL, p < 0.001), while CSF DAT levels were significantly lower in active smokers (0.35 [0.31-0.39] ng/mL vs 0.29 [0.26-0.34] ng/mL, p < 0.001).

CONCLUSION

Cigarette smoking was indeed associated with sleep disturbance, shown by prolonged SOL, higher DA levels and lower DAT levels in CSF of active smokers.

Meta-analytic method reveal a significant association of theBDNF Val66Met variant with smoking persistence based on a large samples

Although numerous genetic studies have reported the link between Val66Met in BDNF gene with smoking, the findings remain controversial, mainly due to small-to-moderate sample sizes. The main aim of current investigation is to explore whether the variant of Val66Met has any genetic functions in the progress of smoking persistence. The Val-based dominant genetic model considering Val/* (namely, Val/Val + Val/Met) and Met/Met as two genotypes with comparison of the frequency of each genotype in current smokers and never smokers. There were seven genetic association articles including eight independent datasets with 10,160 participants were chosen in current meta-analytic investigation. In light of the potent effects of ethnicity on homogeneity across studies, we carried out separated meta-analyses according to the ancestry origin by using the wide-used tool of Comprehensive Meta-analysis software (V 2.0). Our meta-analyses results indicated that the Val66Met polymorphism was significantly linked with smoking persistence based on either all the chosen samples (N = 10,160; Random and fixed models: pooled OR = 1.23; 95% CI = 1.03–1.46; P value = 0.012) or Asian samples (N = 2,095; Fixed model: pooled OR = 1.25; 95% CI = 1.01–1.54; P value = 0.044; Random model: pooled OR = 1.25; 95% CI = 1.001–1.56; P value = 0.049). No significant clue of bias in publications or heterogeneity across studies was detected. Thus, we conclude that the Val66Met (rs6265) variant conveys genetic susceptibility to maintaining smoking, and smokers who carry Val/* genotypes have a higher possibility of maintaining smoking than those having Met/Met genotype.

Ethnic disparities in prevalence and patterns of smoking and nicotine dependence in rural southwest China: a cross-sectional study

OBJECTIVES

This study examines ethnic disparities in prevalence and patterns of smoking and nicotine dependence in rural southwest China.

DESIGN

This was a cross-sectional design.

SETTING

This study was conducted in rural Yunnan Province of China.

PARTICIPANTS

7027 consenting individuals aged ≥35 years among Han majority and four ethnic minority groups (Na Xi, Li Shu, Dai and Jing Po) participated in this study. Information about participants' demographic characteristics as well as smoking habits and an assessment of nicotine dependence with the Fagerstrom Test for Nicotine Dependence (FTND) was obtained using a standard questionnaire.

RESULTS

Males had significantly higher prevalence of current smoking than females (64.8% and 44.4%, p<0.01). Among current smokers, the prevalence of nicotine dependence was significantly higher in males compared with females (19.9% and 7.1%, p<0.01). Jing Po men and women had the highest prevalence of current smokers (72.2% vs 23.1%, p<0.01), whereas the highest prevalence of nicotine dependence was found in male Dai current smokers and female Li Shu current smokers (44.8% vs 32.5%, p<0.01). Filtered cigarettes were the most popular form of tobacco used across all five ethnic groups. Over 75% of tobacco users initiated smoking and regularly smoked during adolescence, and those of minority ethnicity smoked regularly at a younger age than those of Han descent (p<0.05). Individuals in all five ethnic groups with higher levels of education had a lower probability of current smoking status (p<0.05), whereas a negative association of level of education with nicotine dependence was only observed in current smokers in the Han majority and Dai ethnic minority groups. Among Han majority current smokers, higher annual household income was associated with a higher risk of nicotine dependence (p<0.05).

CONCLUSION

Future interventions to control tobacco use should be tailored to address ethnicity and socioeconomic factors.

CSF glutamate level decreases in heavy smokers and negatively correlates with BDI scores

Glutamate is involved in mental disorders and nicotine addiction. The aim of the present study was to evaluate the relationship between cerebrospinal fluid (CSF) glutamate levels and mental status in Chinese heavy smokers. Participants comprised 41 non-smokers and 77 heavy smokers (n = 118). Cerebrospinal fluid was extracted and glutamate levels were measured. We recorded age, years of education, BMI, the Barratt impulsiveness scale (BIS), the Beck Depression Inventory (BDI) and the Self-Rating Anxiety Scale (SAS). BIS action scores, total scores and BDI scores were significantly different between the groups. Partial correlation analyses with age and education years as covariates found that CSF glutamate levels negatively correlated with BDI scores, but did not correlate with SAS scores in heavy smokers. No correlation was found between CSF glutamate levels and BDI or SAS scores in non-smokers. In conclusion, heavy smokers had more impulsivity had lower levels of CSF glutamate and higher BDI scores. CSF glutamate levels negatively correlated with BDI scores in heavy smokers.

Association and cis-mQTL analysis of variants in serotonergic genes associated with nicotine dependence in Chinese Han smokers

Variants in serotonergic genes are implicated in nicotine dependence (ND) in subjects of European and African origin, but their involvement with smoking in Asians is largely unknown. Moreover, mechanisms underlying the ND risk-associated single-nucleotide polymorphisms (SNPs) in these genes are rarely investigated. The Fagerström Test for Nicotine Dependence (FTND) score was used to assess ND in 2616 male Chinese Han smokers. Both association and interaction analysis were used to examine the association of variants in the serotonergic genes with FTND. Further, expression and methylation quantitative trait loci (cis-mQTL) analysis was employed to determine the association of individual SNPs with the extent of methylation of each CpG locus. Individual SNP-based association analysis revealed that rs1176744 in HTR3B was marginally associated with FTND (p = 0.042). Haplotype-based association analysis found that one major haplotype, T-T-A-G, formed by SNPs rs3758987-rs4938056-rs1176744-rs2276305, located in the 5' region of HTR3B, showed a significant association with FTND (p = 0.00025). Further, a significant genetic interactive effect affecting ND was detected among SNPs rs10160548 in HTR3A, and rs3758987, rs2276305, and rs1672717 in HTR3B (p = 0.0074). Finally, we found four CpG sites (CpG_4543549, CpG_4543464, CpG_4543682, and CpG_4546888) to be significantly associated with three cis-mQTL SNPs (i.e., rs3758987, rs4938056, and rs1176744) located in our detected haplotype within HTR3B. In sum, we showed SNP rs1176744 (Tyr129Ser) to be associated with ND. Together with the SNPs rs3758987 and rs4938056 in HTR3B, they formed a major haplotype, which had significant association with ND. We further showed these SNPs contribute to ND through four methylated sites in HTR3B. All these findings suggest that variants in the serotonergic system play an important role in ND in the Chinese Han population. More importantly, these findings demonstrated that the involvement of this system in ND is through gene-by-gene interaction and methylation.

All-Cause and Cancer Mortality Trends in Macheng, China (1984⁻2013): An Age-Period-Cohort Analysis

The aim was to study the variation trends of all-cause and cancer mortality during 1984⁻2013 in Macheng City, China. The mortality data were collected from Macheng City disease surveillance points system and Hubei Center for Disease Control and Prevention. The model life table system was used to adjust mortality rates due to an under-reporting problem. An age-period-cohort model and intrinsic estimator algorithm were used to estimate the age effect, period effect, and cohort effect of all-cause mortality and cancer mortality for males and females. Age effect of all-cause mortality for both sexes increased with age, while the age effect of cancer mortality for both sexes reached a peak at the age group of 55⁻59 years old and then decreased. The relative risks (RRs) of all-cause mortality for males and females declined with the period and decreased by 51.13% and 63.27% during the whole study period, respectively. Furthermore, the period effect of cancer mortality in both sexes decreased at first and then increased. The cohort effect of all-cause and cancer mortality for both sexes born after 1904 presented the pattern of "rise first and then fall," and decreased by 82.18% and 90.77% from cohort 1904⁻1908 to 1989⁻1993, respectively; especially, the risk of all-cause and cancer mortality for both sexes born before 1949 was much higher than that for those born after 1949.

A retrospective study of smoking cessation intervention among university students

This retrospective study investigated the effect of smoking cessation intervention (SCI) among university students in China.Around 192 eligible smokers among university students were included, and were assigned to an intervention group (n = 100), and a control group (n = 92). All included subjects in both groups were recommended to increase fruits and vegetables consumptions. Additionally, participants in the intervention group also underwent SCI therapy for a total of 4 weeks. The outcome measurements consisted of a number of students quit smoking, daily cigarettes, quit attempts, mean days of smoking in the past 30 days, and also stage of change.After 4-week treatment, SCI neither can decrease the number of students quit smoking (P = .21), daily cigarettes (P = .21), quit attempts (P = .07), and mean days of smoking in past 30 days (P = .77), nor can enhance the stage of change (precontemplation, P = .18; contemplation, P = .59; preparation, P = .46).The results of this study showed that after 4-week therapy, SCI may be ineffective for smokers among university students in Chinese.