Nicotine addiction in light smoking African American mothers

The relevance of the unique anatomy of the human prefrontal operculum to the emergence of speech

Identifying the evolutionary origins of human speech remains a topic of intense scientific interest. Here we describe a unique feature of adult human neuroanatomy compared to chimpanzees and other primates that may provide an explanation of changes that occurred to enable the capacity for speech. That feature is the Prefrontal extent of the Frontal Operculum (PFOp) region, which is located in the ventrolateral prefrontal cortex, adjacent and ventromedial to the classical Broca's area. We also show that, in chimpanzees, individuals with the most human-like PFOp, particularly in the left hemisphere, have greater oro-facial and vocal motor control abilities. This critical discovery, when combined with recent paleontological evidence, suggests that the PFOp is a recently evolved feature of human cortical structure (perhaps limited to the genus Homo) that emerged in response to increasing selection for cognitive and motor functions evident in modern speech abilities.

Genomic kinship construction to enhance genetic analyses in the human connectome project data

Imaging genetic analyses quantify genetic control over quantitative measurements of brain structure and function using coefficients of relationship (CR) that code the degree of shared genetics between subjects. CR can be inferred through self-reported relatedness or calculated empirically using genome-wide SNP scans. We hypothesized that empirical CR provides a more accurate assessment of shared genetics than self-reported relatedness. We tested this in 1,046 participants of the Human Connectome Project (HCP) (480 M/566 F) recruited from the Missouri twin registry. We calculated the heritability for 17 quantitative traits drawn from four categories (brain diffusion and structure, cognition, and body physiology) documented by the HCP. We compared the heritability and genetic correlation estimates calculated using self-reported and empirical CR methods Kinship-based INference for GWAS (KING) and weighted allelic correlation (WAC). The polygenetic nature of traits was assessed by calculating the empirical CR from chromosomal SNP sets. The heritability estimates based on whole-genome empirical CR were higher but remained significantly correlated (r ∼0.9) with those obtained using self-reported values. Population stratification in the HCP sample has likely influenced the empirical CR calculations and biased heritability estimates. Heritability values calculated using empirical CR for chromosomal SNP sets were significantly correlated with the chromosomal length (r 0.7) suggesting a polygenic nature for these traits. The chromosomal heritability patterns were correlated among traits from the same knowledge domains; among traits with significant genetic correlations; and among traits sharing biological processes, without being genetically related. The pedigree structures generated in our analyses are available online as a web-based calculator (www.solar-eclipse-genetics.org/HCP).

Variations of cingulate sulcal organization and link with cognitive performance

The sulcal morphology of the human medial frontal cortex has received marked interest because of (1) its remarkable link with the functional organization of this region, and (2) observations that deviations from 'normal' sulcal morphological variability correlate with the prevalence of some psychiatric disorders, cognitive abilities, or personality traits. Unfortunately, background studies on environmental or genetic factors influencing the ontogenesis of the sulcal organization in this region are critically lacking. We analysed the sulcal morphological organization in this region in twins and non-twin siblings, as well as in control subjects for a total of 599 subjects from the Human Connectome Project. The data first confirm significant biases in the presence of paracingulate sulci in left vs right hemispheres in the whole population (twin: p < 2.4.10-9; non-twin: p < 2.10-6) demonstrating a clear general laterality in human subjects. Second, measures of similarity between siblings and estimations of heritability suggest significant environmental factors, in particular in-womb environment, and weak additive genetic factors influencing the presence of a paracingulate sulcus. Finally, we found that relationships between sulcal organization and performance in cognitive, motor, and affective tests depend on the twin status (Twins versus Non-twins). These results provide important new insights to the issue of the significance of sulcal organization in the human medial frontal cortex.

Comparison of heritability estimates on resting state fMRI connectivity phenotypes using the ENIGMA analysis pipeline

We measured and compared heritability estimates for measures of functional brain connectivity extracted using the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) rsfMRI analysis pipeline in two cohorts: the genetics of brain structure (GOBS) cohort and the HCP (the Human Connectome Project) cohort. These two cohorts were assessed using conventional (GOBS) and advanced (HCP) rsfMRI protocols, offering a test case for harmonization of rsfMRI phenotypes, and to determine measures that show consistent heritability for in-depth genome-wide analysis. The GOBS cohort consisted of 334 Mexican-American individuals (124M/210F, average age = 47.9 ± 13.2 years) from 29 extended pedigrees (average family size = 9 people; range 5-32). The GOBS rsfMRI data was collected using a 7.5-min acquisition sequence (spatial resolution = 1.72 × 1.72 × 3 mm³ ). The HCP cohort consisted of 518 twins and family members (240M/278F; average age = 28.7 ± 3.7 years). rsfMRI data was collected using 28.8-min sequence (spatial resolution = 2 × 2 × 2 mm³ ). We used the single-modality ENIGMA rsfMRI preprocessing pipeline to estimate heritability values for measures from eight major functional networks, using (1) seed-based connectivity and (2) dual regression approaches. We observed significant heritability (h² = 0.2-0.4, p < .05) for functional connections from seven networks across both cohorts, with a significant positive correlation between heritability estimates across two cohorts. The similarity in heritability estimates for resting state connectivity measurements suggests that the additive genetic contribution to functional connectivity is robustly detectable across populations and imaging acquisition parameters. The overarching genetic influence, and means to consistently detect it, provides an opportunity to define a common genetic search space for future gene discovery studies.

Heritability estimates on resting state fMRI data using ENIGMA analysis pipeline

Big data initiatives such as the Enhancing NeuroImaging Genetics through Meta-Analysis consortium (ENIGMA), combine data collected by independent studies worldwide to achieve more generalizable estimates of effect sizes and more reliable and reproducible outcomes. Such efforts require harmonized image analyses protocols to extract phenotypes consistently. This harmonization is particularly challenging for resting state fMRI due to the wide variability of acquisition protocols and scanner platforms; this leads to site-to-site variance in quality, resolution and temporal signal-to-noise ratio (tSNR). An effective harmonization should provide optimal measures for data of different qualities. We developed a multi-site rsfMRI analysis pipeline to allow research groups around the world to process rsfMRI scans in a harmonized way, to extract consistent and quantitative measurements of connectivity and to perform coordinated statistical tests. We used the single-modality ENIGMA rsfMRI preprocessing pipeline based on modelfree Marchenko-Pastur PCA based denoising to verify and replicate resting state network heritability estimates. We analyzed two independent cohorts, GOBS (Genetics of Brain Structure) and HCP (the Human Connectome Project), which collected data using conventional and connectomics oriented fMRI protocols, respectively. We used seed-based connectivity and dual-regression approaches to show that the rsfMRI signal is consistently heritable across twenty major functional network measures. Heritability values of 20-40% were observed across both cohorts.

Examination of the Involvement of Cholinergic-Associated Genes in Nicotine Behaviors in European and African Americans

Introduction

Cigarette smoking is a physiologically harmful habit. Nicotinic acetylcholine receptors (nAChRs) are bound by nicotine and upregulated in response to chronic exposure to nicotine. It is known that upregulation of these receptors is not due to a change in mRNA of these genes, however, more precise details on the process are still uncertain, with several plausible hypotheses describing how nAChRs are upregulated. We have manually curated a set of genes believed to play a role in nicotine-induced nAChR upregulation. Here, we test the hypothesis that these genes are associated with and contribute risk for nicotine dependence (ND) and the number of cigarettes smoked per day (CPD).

Methods

Studies with genotypic data on European and African Americans (EAs and AAs, respectively) were collected and a gene-based test was run to test for an association between each gene and ND and CPD.

Results

Although several novel genes were associated with CPD and ND at P < 0.05 in EAs and AAs, these associations did not survive correction for multiple testing. Previous associations between CHRNA3, CHRNA5, CHRNB4 and CPD in EAs were replicated.

Conclusions

Our hypothesis-driven approach avoided many of the limitations inherent in pathway analyses and provided nominal evidence for association between cholinergic-related genes and nicotine behaviors.

Implications

We evaluated the evidence for association between a manually curated set of genes and nicotine behaviors in European and African Americans. Although no genes were associated after multiple testing correction, this study has several strengths: by manually curating a set of genes we circumvented the limitations inherent in many pathway analyses and tested several genes that had not yet been examined in a human genetic study; gene-based tests are a useful way to test for association with a set of genes; and these genes were collected based on literature review and conversations with experts, highlighting the importance of scientific collaboration.

Polymorphisms in HTR2A and DRD4 Predispose to Smoking and Smoking Quantity

BACKGROUND

Genes encoding the receptors involved in the dopaminergic and serotonergic pathways are potential candidates in the mechanisms of nicotine addiction.

AIMS

To identify genetic variants in the promoter regions and exons of the DRD4 and HTR2A genes associated with tobacco smoking and the degree of nicotine addiction in Mexican mestizos.

METHODS

The study included 438 non-smokers (NS) and 1,157 current smokers, ranked based on their consumption of cigarettes per day (cpd): 574 heavy smokers (HS, >20 cpd) and 583 light smokers (LS, 1-10 cpd). Genotyping was performed for 4 and 8 single nucleotide polymorphisms (SNPs) in the DRD4 and HTR2A genes, respectively.

RESULTS

The C allele of rs1800955 in DRD4 was found to be associated with cigarette smoking in the HS vs. NS and LS vs. NS comparisons (p = 2.34E-03 and p = 1.13E-03, respectively); the association was maintained in the homozygous CC genotype (p = 5.00E-04 and p = 2.00E-04, respectively). The T allele of rs6313 in HTR2A was significantly associated with cigarette smoking and a greater degree of nicotine addiction (p = 4.77E-03, OR = 1.55); the association was maintained in the homozygous genotype (TT) (p = 4.90E-03, OR = 1.96). The A allele of rs6313 was associated with cigarette smoking in the HS vs. NS comparison (p = 1.53E-02, OR = 1.36); the risk was nearly doubled in the homozygous AA genotype (p = 1.30E-03, OR = 1.83) compared with the heterozygous GA genotype (OR = 1.38).

CONCLUSIONS

Among Mexican mestizos, the C allele of rs1800955 in the DRD4 gene and the A allele of rs6311 in the HTR2A gene are associated with cigarette smoking, whereas the T allele of rs6313 in HTR2A is associated with cigarette smoking and the degree of nicotine addiction.

The common genetic influence over processing speed and white matter microstructure: Evidence from the Old Order Amish and Human Connectome Projects

Speed with which brain performs information processing influences overall cognition and is dependent on the white matter fibers. To understand genetic influences on processing speed and white matter FA, we assessed processing speed and diffusion imaging fractional anisotropy (FA) in related individuals from two populations. Discovery analyses were performed in 146 individuals from large Old Order Amish (OOA) families and findings were replicated in 485 twins and siblings of the Human Connectome Project (HCP). The heritability of processing speed was h(2)=43% and 49% (both p<0.005), while the heritability of whole brain FA was h(2)=87% and 88% (both p<0.001), in the OOA and HCP, respectively. Whole brain FA was significantly correlated with processing speed in the two cohorts. Quantitative genetic analysis demonstrated a significant degree to which common genes influenced joint variation in FA and brain processing speed. These estimates suggested common sets of genes influencing variation in both phenotypes, consistent with the idea that common genetic variations contributing to white matter may also support their associated cognitive behavior.

Heritability of fractional anisotropy in human white matter: a comparison of Human Connectome Project and ENIGMA-DTI data

The degree to which genetic factors influence brain connectivity is beginning to be understood. Large-scale efforts are underway to map the profile of genetic effects in various brain regions. The NIH-funded Human Connectome Project (HCP) is providing data valuable for analyzing the degree of genetic influence underlying brain connectivity revealed by state-of-the-art neuroimaging methods. We calculated the heritability of the fractional anisotropy (FA) measure derived from diffusion tensor imaging (DTI) reconstruction in 481 HCP subjects (194/287 M/F) consisting of 57/60 pairs of mono- and dizygotic twins, and 246 siblings. FA measurements were derived using (Enhancing NeuroImaging Genetics through Meta-Analysis) ENIGMA DTI protocols and heritability estimates were calculated using the SOLAR-Eclipse imaging genetic analysis package. We compared heritability estimates derived from HCP data to those publicly available through the ENIGMA-DTI consortium, which were pooled together from five-family based studies across the US, Europe, and Australia. FA measurements from the HCP cohort for eleven major white matter tracts were highly heritable (h(2)=0.53-0.90, p<10(-5)), and were significantly correlated with the joint-analytical estimates from the ENIGMA cohort on the tract and voxel-wise levels. The similarity in regional heritability suggests that the additive genetic contribution to white matter microstructure is consistent across populations and imaging acquisition parameters. It also suggests that the overarching genetic influence provides an opportunity to define a common genetic search space for future gene-discovery studies. Uniquely, the measurements of additive genetic contribution performed in this study can be repeated using online genetic analysis tools provided by the HCP ConnectomeDB web application.

Predictors of cessation in African American light smokers enrolled in a bupropion clinical trial

BACKGROUND

This is the first study to examine predictors of successful cessation in African American (AA) light smokers treated within a placebo-controlled trial of bupropion.

METHODS

We analyzed data from a randomized, double-blind, placebo-controlled trial of bupropion and health education for 540 African American light smokers. African American light smokers (≤10 cigarettes per day, cpd) were randomly assigned to receive 150mg bid bupropion SR (n=270) or placebo (n=270) for 7weeks. All participants received health education counseling at weeks 0, 1, 3, 5 and 7. Using chi-square tests, two sample t-tests, and multiple logistic regression analyses, we examined baseline psychosocial and smoking characteristics as predictors of cotinine-verified 7-day point prevalence smoking abstinence among study participants at the end treatment (Week 7) and at the end of follow-up (Week 26).

RESULTS

Participants who received bupropion were significantly more likely to quit smoking compared to those who received placebo (OR=2.72, 95% CI=1.60-4.62, P=0.0002). Greater study session attendance (OR=2.47, 95% CI=1.76-3.46, P=0.0001), and smoking non-menthol cigarettes increased the likelihood of quitting (OR=1.84, 95% CI=1.01-3.36, P=0.05); while longer years of smoking (OR=0.98, 95% CI=0.96-1.00, P=0.05) and higher baseline cotinine (OR=0.97, 95% CI=0.95-0.99, P=0.002) significantly reduced the odds of quitting at Week 7. Conversely, at the end of follow-up (Week 26), treatment with bupropion vs. placebo (OR=1.14, 95% CI=0.65-2.02, P=0.64) was not significantly associated with quitting and type of cigarette smoked (menthol vs. non-menthol) did not appear in the final logistic regression model. Greater study session attendance (OR=1.96, 95% CI=1.44-2.66, P=0.0001); BMI (OR=1.03, 95% CI=1.00-1.07, P=0.04); and weight efficacy (OR=1.03, 95% CI=1.01-1.05, P=0.01) increased the likelihood of quitting at Week 26. Similar to our findings at Week 7, longer years of smoking (OR=0.96, 95% CI=0.94-0.99, P=0.01) and higher baseline cotinine (OR=0.97, 95% CI=0.95-0.99, P=0.02) significantly reduced the odds of quitting at Week 26.

CONCLUSIONS

Baseline cotinine levels, number of years smoked and study session attendance are associated with both short- and long-term smoking cessation, while bupropion and the type of cigarette smoked were associated with quitting on short term only.

Differences in time to onset of smoking and nicotine dependence by race/ethnicity in a Midwestern sample of adolescents and young adults from a high risk family study

OBJECTIVE

The objective of this study was to determine whether race/ethnicity was associated with time to smoking initiation and time from first cigarette to onset of DSM-IV nicotine dependence (ND) after adjusting for familial and individual psychosocial risk factors.

METHODS

Cox proportional hazards models with time-dependent covariates were used to analyze data from 1376 offspring aged 12-33 years from 532 families at high risk for substance use problems due to paternal alcohol problems and 235 low risk families. Fifty-six percent of the sample self-identified as African-American (AA) and 44% were mainly of European descent.

RESULTS

Controlling for covariates, AAs began smoking at older ages (HR=0.58; 95% CI: 0.48-0.70) and had longer times between smoking initiation and onset of ND compared to non-AAs (HR=0.25, 95% CI: 0.16-0.39 for ND onset occurring <18 years and HR=0.49, 95% CI: 0.30-0.80 for ND onsets ≥ age 18). After additionally controlling for number of cigarettes smoked daily, the racial/ethnic effects for onset of ND were attenuated, but remained statistically significant for ND onset <18 (HR=0.34, 95% CI: 0.19-0.61); however, the estimate was no longer significant for later ND onset (HR=0.84, 95% CI: 0.50-1.41).

CONCLUSIONS

AA adolescents and young adults initiate smoking at older ages and have longer transition periods between initiation and onset of ND compared to non-AAs, even after controlling for many relevant psychiatric and psychosocial covariates; however, racial/ethnic differences in time to onset of nicotine dependence in late adolescence and young adulthood may be explained by differences in daily quantity smoked.

The Human Connectome Project: a data acquisition perspective

The Human Connectome Project (HCP) is an ambitious 5-year effort to characterize brain connectivity and function and their variability in healthy adults. This review summarizes the data acquisition plans being implemented by a consortium of HCP investigators who will study a population of 1200 subjects (twins and their non-twin siblings) using multiple imaging modalities along with extensive behavioral and genetic data. The imaging modalities will include diffusion imaging (dMRI), resting-state fMRI (R-fMRI), task-evoked fMRI (T-fMRI), T1- and T2-weighted MRI for structural and myelin mapping, plus combined magnetoencephalography and electroencephalography (MEG/EEG). Given the importance of obtaining the best possible data quality, we discuss the efforts underway during the first two years of the grant (Phase I) to refine and optimize many aspects of HCP data acquisition, including a new 7T scanner, a customized 3T scanner, and improved MR pulse sequences.

Sociodemographic and substance use correlates of tobacco use in a large, multi-ethnic sample of emergency department patients

Strong evidence suggests marked disparities among ethnic minorities in relation to tobacco use. To date, a majority of the data available discusses tobacco use in the general population. Using a sample of Latino, non-Latino Black (NLB), and non-Latino White (NLW) patients presenting to the emergency departments, the present study examined sociodemographic and substance use correlates of past 3-month tobacco use. Over 48,000 patients were interviewed as part of a screening and brief intervention program in southern California. Overall, although NLB adults reported the greatest prevalence of tobacco use compared to NLWs and Latinos (43% vs. 34% and 22% respectively), associations between tobacco use, demographics and substance use were similar across groups. Males, younger individuals, those with lower income, and being at higher risk for alcohol and drug use were more likely to report recent tobacco use. Future tobacco interventions in emergency settings should highlight these specific risk factors for Latinos, NLBs, and NLWs.

Ethnoracial differences in emergency department patients' tobacco use

INTRODUCTION

This study examined ethnoracial differences in lifetime and recent tobacco use and related problems in a large convenience sample of Latino, Black, and Non-Latino White emergency department (ED) patients. In addition, ED patients' use rates were compared with those of a statewide sample.

METHODS

Trained bilingual/bicultural health educators screened almost 53,000 ED patients in 8 ED/trauma units throughout San Diego County over a 2-year period. Measures included sociodemographic characteristics and tobacco use measures from the Alcohol, Smoking, and Substance Involvement Screening Test brief screening instrument.

RESULTS

A consistent finding was the lower prevalence of tobacco use among Latino patients compared with Black and Non-Latino White patients. Compared with their general population counterparts, Non-Latino White, Latino, and Black patients were more likely to have used tobacco in their lifetime and on a daily basis.

CONCLUSIONS

Results indicate the high tobacco risk status of ED patients, regardless of ethnicity. More work is needed to develop effective approaches for ED-initiated tobacco interventions for patients in various racial/ethnic groups. Offering tobacco cessation support in opportune venues such as the ED holds great potential to improve accessibility to public health interventions for many underserved communities who may not have regular interaction with a primary care provider.

Self-reported tobacco smoking practices among medical students and their perceptions towards training about tobacco smoking in medical curricula: A cross-sectional, questionnaire survey in Malaysia, India, Pakistan, Nepal, and Bangladesh

Background

Tobacco smoking issues in developing countries are usually taught non-systematically as and when the topic arose. The World Health Organisation and Global Health Professional Student Survey (GHPSS) have suggested introducing a separate integrated tobacco module into medical school curricula. Our aim was to assess medical students' tobacco smoking habits, their practices towards patients' smoking habits and attitude towards teaching about smoking in medical schools.

Methods

A cross-sectional questionnaire survey was carried out among final year undergraduate medical students in Malaysia, India, Nepal, Pakistan, and Bangladesh. An anonymous, self-administered questionnaire included items on demographic information, students' current practices about patients' tobacco smoking habits, their perception towards tobacco education in medical schools on a five point Likert scale. Questions about tobacco smoking habits were adapted from GHPSS questionnaire. An 'ever smoker' was defined as one who had smoked during lifetime, even if had tried a few puffs once or twice. 'Current smoker' was defined as those who had smoked tobacco product on one or more days in the preceding month of the survey. Descriptive statistics were calculated.

Results

Overall response rate was 81.6% (922/1130). Median age was 22 years while 50.7% were males and 48.2% were females. The overall prevalence of 'ever smokers' and 'current smokers' was 31.7% and 13.1% respectively. A majority (> 80%) of students asked the patients about their smoking habits during clinical postings/clerkships. Only a third of them did counselling, and assessed the patients' willingness to quit. Majority of the students agreed about doctors' role in tobacco control as being role models, competence in smoking cessation methods, counseling, and the need for training about tobacco cessation in medical schools. About 50% agreed that current curriculum teaches about tobacco smoking but not systematically and should be included as a separate module. Majority of the students indicated that topics about health effects, nicotine addiction and its treatment, counselling, prevention of relapse were important or very important in training about tobacco smoking.

Conclusion

Medical educators should consider revising medical curricula to improve training about tobacco smoking cessation in medical schools. Our results should be supported by surveys from other medical schools in developing countries of Asia.

Early drinking and its association with adolescents' participation in risky behaviors

BACKGROUND

Adolescent alcohol use is a significant public health problem. Drinking before 13 years of age is correlated to the use of illicit drugs and other risky behaviors, such as cigarette smoking.

OBJECTIVE

The purpose of this research was to examine the relationship between adolescents' early alcohol use and participation in risky behaviors such as smoking marijuana and cigarettes, as well as risky sexual behaviors.

STUDY DESIGN

Respondents for this cross-sectional secondary analysis came from a sample of 809 racially diverse adolescents in a community-based study examining familial influences on offspring outcomes.

RESULTS

Early-onset drinking, compared with nondrinking, was significantly related to participating in many of the risky behaviors. Many of the relationships persisted in the multivariable models that adjusted for demographic characteristics.

CONCLUSIONS

Early drinking was associated with participation in various risky behaviors (e.g., multiple sexual partners, unprotected intercourse), which may negatively alter an adolescent's future. Screening should focus on the co-occurrence of such behaviors.