Smoking cessation, harm reduction, and biomarkers protocols in the PhenX Toolkit: Tools for standardized data collection.

The use of standard protocols in studies supports consistent data collection, improves data quality, and facilitates cross-study analyses. Funded by the National Institutes of Health, the PhenX (consensus measures for Phenotypes and eXposures) Toolkit is a catalog of recommended measurement protocols that address a wide range of research topics and are suitable for inclusion in a variety of study designs. In 2020, a PhenX Working Group of smoking cessation experts followed a well-established consensus process to identify and recommend measurement protocols suitable for inclusion in smoking cessation and smoking harm reduction studies. The broader scientific community was invited to review and provide feedback on the preliminary recommendation of the Working Group. Fourteen selected protocols for measuring smoking cessation, harm reduction, and biomarkers research associated with smoking cessation were released in the PhenX Toolkit ( https://www.phenxtoolkit.org) in February 2021. These protocols complement existing PhenX Toolkit content related to tobacco regulatory research, substance use and addiction research, and other measures of smoking-related health outcomes. Adopting well-established protocols enables consistent data collection and facilitates comparing and combining data across studies, potentially increasing the scientific impact of individual studies.

Association of State Medicaid Expansion Status With Rates of Suicide Among US Adults.

Importance: In the US, suicide is the 10th leading cause of death and a serious mental health emergency. National programs that address suicide list access to mental health care as key in prevention, and more large-scale policies are needed to improve access to mental health care and address this crisis. The Patient Protection and Affordable Care Act (ACA) Medicaid Expansion Program was implemented in several states with the goal of increasing access to the health care system. Objective: To compare changes in suicide rates in states that expanded Medicaid under the ACA vs states that did not. Design, Setting, and Participants: In this cross-sectional study, state-level mortality rates were obtained from the National Center for Health Statistics for US individuals aged 20 to 64 years from January 1, 2000, to December 31, 2018. Data analysis was performed from April 18, 2021, to April 15, 2022. Exposures: Changes in suicide mortality rates among nonelderly adults before and after Medicaid expansion in expansion and nonexpansion states were compared using adjusted difference-in-differences analyses via hierarchical bayesian linear regression. Main Outcomes and Measures: Suicide rates using death by suicide as the primary measure. Results: Of the total population at risk for suicide, 50.4% were female, 13.3% were Black, 79.5% were White, and 7.2% were of other races. The analytic data set contained suicide mortality data for 2907 state-age-year units covering the general US population. A total of 553 912 deaths by suicide occurred during the study period, with most occurring in White (496 219 [89.6%]) and male (429 580 [77.6%]) individuals. There were smaller increases in the suicide rate after 2014 in Medicaid expansion (2.56 per 100 000 increase) compared with nonexpansion states (3.10 per 100 000 increase). In adjusted difference-in-differences analysis, a significant decrease of -0.40 (95% credible interval, -0.66 to -0.14) suicides per 100 000 individuals was found, translating to 1818 suicides that were averted in 2015 to 2018. Conclusions and Relevance: In this cross-sectional study, although suicide rates increased in both groups, blunting of these rates occurred among nonelderly adults in the Medicaid expansion states compared with nonexpansion states. Because this difference may be linked to increased access to mental health care, policy makers should consider suicide prevention as a benefit of expanding access to health care.

Physicians-in-training are not prepared to prescribe medical marijuana.

BACKGROUND: While medical marijuana use is legal in more than half of U.S. states, evidence is limited about the preparation of physicians-in-training to prescribe medical marijuana. We asked whether current medical school and graduate medical educational training prepare physicians to prescribe medical marijuana. METHODS: We conducted a national survey of U.S. medical school curriculum deans, a similar survey of residents and fellows at Washington University in St. Louis, and a query of the Association of American Medical Colleges (AAMC) Curriculum Inventory database for keywords associated with medical marijuana. RESULTS: Surveys were obtained from 101 curriculum deans, and 258 residents and fellows. 145 schools were included in the curriculum search. The majority of deans (66.7%) reported that their graduates were not at all prepared to prescribe medical marijuana, and 25.0% reported that their graduates were not at all prepared to answer questions about medical marijuana. The vast majority of residents and fellows (89.5%) felt not at all prepared to prescribe medical marijuana, while 35.3% felt not at all prepared to answer questions, and 84.9% reported receiving no education in medical school or residency on medical marijuana. Finally, only 9% of medical school curriculums document in the AAMC Curriculum Inventory database content on medical marijuana. CONCLUSIONS: Our study highlights a fundamental mismatch between the state-level legalization of medical marijuana and the lack of preparation of physicians-in-training to prescribe it. With even more states on the cusp of legalizing medical marijuana, physician training should adapt to encompass this new reality of medical practice.

Twitter chatter about marijuana.

PURPOSE: We sought to examine the sentiment and themes of marijuana-related chatter on Twitter sent by influential Twitter users and to describe the demographics of these Twitter users. METHODS: We assessed the sentiment and themes of a random sample (n = 7,000) of influential marijuana-related tweets (sent from February 5, 20114, to March 5, 2014). Demographics of the users tweeting about marijuana were inferred using a social media analytics company (Demographics Pro for Twitter). RESULTS: Most marijuana-related tweets reflected a positive sentiment toward marijuana use, with pro-marijuana tweets outnumbering anti-marijuana tweets by a factor of greater than 15. The most common theme of pro-marijuana tweets included the Tweeter stating that he/she wants/plans to use marijuana, followed by tweeting about frequent/heavy/or regular marijuana use, and that marijuana has health benefits and/or should be legalized. Tweeters of marijuana-related content were younger and a greater proportion was African-American compared with the Twitter average. CONCLUSIONS: Marijuana Twitter chatter sent by influential Twitter users tends to be pro-marijuana and popular among African-Americans and youth/young adults. Marijuana-related harms may afflict some individuals; therefore, our findings should be used to inform online and offline prevention efforts that work to target individuals who are most at risk for harms associated with marijuana use.

Maternal age and risk of labor and delivery complications.

We utilized an updated nationally representative database to examine associations between maternal age and prevalence of maternal morbidity during complications of labor and delivery. We used hospital inpatient billing data from the 2009 United States Nationwide Inpatient Sample, part of the Healthcare Cost and Utilization Project. To determine whether the likelihood that maternal morbidity during complications of labor and delivery differed among age groups, separate logistic regression models were run for each complication. Age was the main independent variable of interest. In analyses that controlled for demographics and clinical confounders, we found that complications with the highest odds among women, 11-18 years of age, compared to 25-29 year old women, included preterm delivery, chorioamnionitis, endometritis, and mild preeclampsia. Pregnant women who were 15-19 years old had greater odds for severe preeclampsia, eclampsia, postpartum hemorrhage, poor fetal growth, and fetal distress. Pregnant women who were ≥35 years old had greater odds for preterm delivery, hypertension, superimposed preeclampsia, severe preeclampsia, and decreased risk for chorioamnionitis. Older women (≥40 years old) had increased odds for mild preeclampsia, fetal distress, and poor fetal growth. Our findings underscore the need for pregnant women to be aware of the risks associated with extremes of age so that they can watch for signs and symptoms of such complications.

Monitoring of non-cigarette tobacco use using Google Trends.

BACKGROUND: Google Trends is an innovative monitoring system with unique potential to monitor and predict important phenomena that may be occurring at a population level. We sought to validate whether Google Trends can additionally detect regional trends in youth and adult tobacco use. METHODS: We compared 2011 Google Trends relative search volume data for cigars, cigarillos, little cigars and smokeless tobacco with state prevalence of youth (grades 9-12) and adult (age 18 and older) use of these products using data from the 2011 United States state-level Youth Risk Behaviors Surveillance System and the 2010-2011 United States National Survey on Drug Use and Health (NSDUH), respectively. We used the Pearson correlation coefficient to measure the associations. RESULTS: We found significant positive correlations between state Google Trends cigar relative search volume and prevalence of cigar use among youth (r=0.39, R(2) = 0.154, p=0.018) and adults (r=0.49, R(2) = 0.243, p<0.001). Similarly, we found that the correlations between state Google Trends smokeless tobacco relative search volume and prevalence of smokeless tobacco use among youth and adults were both positive and significant (r=0.46, R(2) = 0.209, p=0.003 and r=0.48, R(2) = 0.226, p<0.001, respectively). CONCLUSIONS: The results of this study validate that Google Trends has the potential to be a valuable monitoring tool for tobacco use. The near real-time monitoring features of Google Trends may complement traditional surveillance methods and lead to faster and more convenient monitoring of emerging trends in tobacco use.

Youth tobacco use type and associations with substance use disorders.

AIMS: To examine the associations between youth poly-tobacco use and substance use disorders. DESIGN: Analysis of data from the 2007-11 US National Survey on Drug Use and Health. SETTING: Randomly selected, household-dwelling adolescents from the non-institutionalized, civilian population of the United States. PARTICIPANTS: A total of 91 152 adolescents (aged 12-17 years). METHODS: Logistic regression models were used to examine the associations between type of tobacco user (non-user, users of alternative tobacco products only, users of cigarettes only and users of cigarettes plus alternative tobacco products) with past year alcohol, marijuana or other illicit drug use disorders, adjusting for demographic and social variables. FINDINGS: Compared with non-users of tobacco, the greatest risk for substance use disorders was among users of cigarettes plus alternative tobacco products [alcohol disorder adjusted odds ratio (aOR) = 18.3, 95% confidence interval (CI) = 16.2-20.6; marijuana disorder aOR = 37.2, 95% CI = 32.5-42.7; other drug disorder aOR = 18.4, 95% CI = 15.4-21.8], followed by users of cigarettes only (alcohol disorder aOR = 9.6, 95% CI = 8.8-10.6; marijuana disorder aOR = 20.4, 95% CI = 18.1-23.0; other drug disorder aOR = 9.4, 95% CI = 7.8-11.4), then users of alternative tobacco products only (alcohol disorder aOR = 8.1, 95% CI = 6.7-9.6; marijuana disorder aOR = 9.2, 95% CI = 7.5-11.4; other drug disorder aOR = 3.2, 95% CI = 2.4-4.3). CONCLUSIONS: Tobacco use in adolescence is associated with higher rates of substance use disorders across all tobacco users, especially among those who use cigarettes plus other tobacco products.

CHRNA5 variant predicts smoking cessation in patients with acute myocardial infarction.

INTRODUCTION: While smoking is a major modifiable risk factor for secondary prevention of myocardial infarction (MI), active smoking is common among patients hospitalized with acute MI. Recent studies suggest that nicotinic receptor variants, and specifically the high-risk CHRNA5 rs16969968 A allele, are associated with cessation failure among noncardiac patients. This study investigates the association between CHRNA5 rs16969968 and smoking cessation in patients hospitalized with acute MI. METHODS: Using data from the TRIUMPH study, we ascertained smoking status at the time of index hospitalization for acute MI and 1 year after hospitalization. After adjusting for age and sex, we used logistic regression to model the association between smoking cessation and CHRNA5 rs16969968. RESULTS: At index admission, 752 Caucasian subjects were active smokers and 699 were former smokers. Among these ever-smokers, the A allele was associated with significantly decreased abstinence (45.0% abstinence for A allele carriers vs. 51.7% for GG homozygotes; odds ratio [OR] = 0.70, 95% confidence interval [CI] = 0.56-0.88, p = .0027). The A allele was also significantly associated with decreased abstinence at 1 year (69.1% abstinence for A allele carriers vs. 76.0% for GG homozygotes; OR = 0.70, 95% CI = 0.53-0.94, p = .0185). CONCLUSIONS: Among patients who have smoked and who are hospitalized with acute MI, the high-risk CHRNA5 allele was associated with lower likelihood of quitting before hospitalization and significantly less abstinence 1 year after hospitalization with MI. The CHRNA5 rs16969968 genotype may therefore identify patients who would benefit from aggressive, personalized smoking cessation intervention.

Hazards of new media: youth's exposure to tobacco Ads/promotions.

BACKGROUND: A gap in knowledge exists about the youth's exposure to protobacco campaigns via new electronic media outlets. In response, we use national data to delineate the associations between tobacco ads/promotions delivered through new media outlets (i.e., social network sites and text messages) and youth attitudes/beliefs about tobacco and intent to use (among youth who had not yet used tobacco). METHODS: Data were derived from the 2011 National Youth Tobacco Survey, a nationally representative sample of U.S. youth enrolled in both public and private schools (N = 15,673). Logistic regression models were used to examine associations between demographic characteristics and reported exposure to tobacco ads/promotions via social networking sites and text messages. Logistic regression models were also used to investigate associations between exposure tobacco ads/promotions and attitudes toward tobacco. RESULTS: We found that highly susceptible youth (i.e., minorities, very young youth, and youth who have not yet used tobacco) have observed tobacco ads/promotions on social networking sites and text messages. These youth are more likely to have favorable attitudes toward tobacco, including the intention to use tobacco among those who had not yet used tobacco. CONCLUSIONS: Our findings underscore the need for policy strategies to more effectively monitor and regulate tobacco advertising via new media outlets.

A glimpse into the future - Personalized medicine for smoking cessation.

The devastating consequences of tobacco smoking for individuals and societies motivate studies to identify and understand the biological pathways that drive smoking behaviors, so that more effective preventions and treatments can be developed. Cigarette smokers respond to nicotine in different ways, with a small number of smokers remaining lifelong low-level smokers who never exhibit any symptoms of dependence, and a larger group becoming nicotine dependent. Whether or not a smoker transitions to nicotine dependence has clear genetic contributions, and variants in the genes encoding the α5-α3-ß4 nicotinic receptor subunits most strongly contribute to differences in the risk for developing nicotine dependence among smokers. More recent work reveals a differential response to pharmacologic treatment for smoking cessation based on these same genetic variants in the α5-α3-ß4 nicotinic receptor gene cluster. We anticipate a continuing acceleration of the translation of genetic discoveries into more successful treatment for smoking cessation. Given that over 400,000 people in the United States and over 5 million people world-wide die each year from smoking related illnesses, an improved understanding of the mechanisms underlying smoking behavior and smoking cessation must be a high public health priority so we can best intervene at both the public health level and the individual level. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Differential effects of cigarette price changes on adult smoking behaviours.

BACKGROUND: Raising cigarette prices through taxation is an important policy approach to reduce smoking. Yet, cigarette price increases may not be equally effective in all subpopulations of smokers. PURPOSE: To examine differing effects of state cigarette price changes with individual changes in smoking among smokers of different intensity levels. METHODS: Data were derived from the National Epidemiologic Survey on Alcohol and Related Conditions, a nationally representative sample of US adults originally interviewed in 2001-2002 (Wave 1) and re-interviewed in 2004-2005 (Wave 2): 34 653 were re-interviewed in Wave 2, and 7068 smokers defined at Wave 1 were included in our study. Mixed effects linear regression models were used to assess whether the effects of changes in state cigarette prices on changes in daily smoking behaviour differed by level of daily smoking. RESULTS: In the multivariable model, there was a significant interaction between change in price per pack of cigarettes from Wave 1 to Wave 2 and the number of cigarettes smoked per day (p=0.044). The more cigarettes smoked per day at baseline, the more responsive the smokers were to increases in price per pack of cigarettes (ie, number of cigarettes smoked per day was reduced in response to price increases). CONCLUSIONS: Our findings that heavier smokers successfully and substantially reduced their cigarette smoking behaviours in response to state cigarette price increases provide fresh insight to the evidence on the effectiveness of higher cigarette prices in reducing smoking.

Characteristics of sexually active teenage girls who would be pleased with becoming pregnant.

To investigate factors associated with favorable pregnancy attitudes among teenage girls. Participants were sexually active teenage girls aged 15-18 years old (n = 965) who took part in the 2002 or 2006-2010 National Survey of Family Growth (NSFG). Multinomial multivariable logistic regression was used to assess the likelihood of being pleased with a teenage pregnancy. Sixteen percent of sexually active teenage girls (n = 164) would be pleased (11 % a little pleased, 5 % very pleased) if they became pregnant. In a multivariable model, participants who had not yet discussed sexual health topics (i.e., how to say no to sexual intercourse or birth control) or had only discussed birth control with a parent were more likely to be very pleased with a teenage pregnancy than participants who had discussed both topics with a parent. Prior pregnancy, racial/ethnic group status, older age, and having parents with a high school education or less also increased the odds of being pleased with a teenage pregnancy. Being pleased with a teenage pregnancy was correlated with a lack of discussion of sexual health topics with parents, prior pregnancy, and sociodemographic factors (having less educated parents, racial/ethnic group status). Pregnancy prevention efforts can be improved by acknowledging the structural and cultural factors that shape teenage pregnancy attitudes.

Convergence of genome-wide association and candidate gene studies for alcoholism.

BACKGROUND: Genome-wide association (GWA) studies have led to a paradigm shift in how researchers study the genetics underlying disease. Many GWA studies are now publicly available and can be used to examine whether or not previously proposed candidate genes are supported by GWA data. This approach is particularly important for the field of alcoholism because the contribution of many candidate genes remains controversial. METHODS: Using the Human Genome Epidemiology (HuGE) Navigator, we selected candidate genes for alcoholism that have been frequently examined in scientific articles in the past decade. Specific candidate loci as well as all the reported single nucleotide polymorphisms (SNPs) in candidate genes were examined in the Study of Addiction: Genetics and Environment (SAGE), a GWA study comparing alcohol-dependent and nondependent subjects. RESULTS: Several commonly reported candidate loci, including rs1800497 in DRD2, rs698 in ADH1C, rs1799971 in OPRM1, and rs4680 in COMT, are not replicated in SAGE (p > 0.05). Among candidate loci available for analysis, only rs279858 in GABRA2 (p = 0.0052, OR = 1.16) demonstrated a modest association. Examination of all SNPs reported in SAGE in over 50 candidate genes revealed no SNPs with large frequency differences between cases and controls, and the lowest p-value of any SNP was 0.0006. CONCLUSIONS: We provide evidence that several extensively studied candidate loci do not have a strong contribution to risk of developing alcohol dependence in European and African ancestry populations. Owing to the lack of coverage, we were unable to rule out the contribution of other variants, and these genes and particular loci warrant further investigation. Our analysis demonstrates that publicly available GWA results can be used to better understand which if any of previously proposed candidate genes contribute to disease. Furthermore, we illustrate how examining the convergence of candidate gene and GWA studies can help elucidate the genetic architecture of alcoholism and more generally complex diseases.

Interplay of genetic risk factors (CHRNA5-CHRNA3-CHRNB4) and cessation treatments in smoking cessation success.

OBJECTIVE: Smoking is highly intractable, and the genetic influences on cessation are unclear. Identifying the genetic factors affecting smoking cessation could elucidate the nature of tobacco dependence, enhance risk assessment, and support development of treatment algorithms. This study tested whether variants in the nicotinic receptor gene cluster CHRNA5-CHRNA3-CHRNB4 predict age at smoking cessation and relapse after an attempt to quit smoking. METHOD: In a community-based, crosssectional study (N=5,216) and a randomized comparative effectiveness smoking cessation trial (N=1,073), the authors used Cox proportional hazard models and logistic regression to model the relationships of smoking cessation (self-reported quit age in the community study and point-prevalence abstinence at the end of treatment in the clinical trial) to three common haplotypes in the CHRNA5-CHRNA3-CHRNB4 region defined by rs16969968 and rs680244. RESULTS: The genetic variants in the CHRNA5-CHRNA3-CHRNB4 region that predict nicotine dependence also predicted a later age at smoking cessation in the community sample. In the smoking cessation trial, haplotype predicted abstinence at end of treatment in individuals receiving placebo but not among individuals receiving active medication. Haplotype interacted with treatment in affecting cessation success. CONCLUSIONS: Smokers with the high-risk haplotype were three times as likely to respond to pharmacologic cessation treatments as were smokers with the low-risk haplotype. The high-risk haplotype increased the risk of cessation failure, and this increased risk was ameliorated by cessation pharmacotherapy. By identifying a high-risk genetic group with heightened response to smoking cessation pharmacotherapy, this work may support the development of personalized cessation treatments.

Associations between selected state laws and teenagers' drinking and driving behaviors.

BACKGROUND: We examined the associations between selected state-level graduated driving licensing (GDL) laws and use-and-lose laws (laws that allow for the suspension of a driver's license for underage alcohol violations including purchase, possession, or consumption) with individual-level alcohol-related traffic risk behaviors among high school youth. METHODS: Logistic regression models with fixed effects for state were used to examine the associations between the selected state-level laws and drinking and driving behaviors youth aged 16 to 17 years (obtained from the Youth Risk Behavior Surveillance System (YRBSS); responses dichotomized as "0 times" or "1 or more times") over an extended period of time (1999 to 2009). RESULTS: A total of 11.7% of students reported having driven after drinking any alcohol and 28.2% reported riding in a car with a driver who had been drinking on 1 or more occasions in the past 30 days. Restrictive GDL laws and use-and-lose laws were associated with decreased driving after drinking any alcohol and riding in a car with a driver who had been drinking alcohol. CONCLUSIONS: Restrictive GDL and use-and-lose laws may help to bolster societal expectations and values about the hazards of drinking and driving behaviors and are therefore partly responsible for the decline in these alcohol-related traffic risk behaviors.

Brief report: Pregnant by age 15 years and substance use initiation among US adolescent girls.

We examined substance use onset and associations with pregnancy by age 15 years. Participants were girls ages 15 years or younger (weighted n = 8319) from the 1999-2003 Youth Risk Behavior Surveillance System (YRBS). Multivariable logistic regression examined pregnancy as a function of substance use onset (i.e., age 10 years or younger, 11-12, 13-14, and age 15 years) for alcohol, cigarettes and marijuana, controlling for race/ethnicity and metropolitan location. Of girls pregnant by age 15 years (3% of the sample, weighted n = 243), 16% had smoked marijuana by age 10 years and over 20% had smoked cigarettes and initiated alcohol use by age 10 years. In the multivariable analysis, marijuana use by age 14 years and/or cigarette smoking by age 12 years clearly distinguished girls who became pregnant by age 15 years and is perhaps due to a common underlying risk factor.

Associations between sexuality education in schools and adolescent birthrates: a state-level longitudinal model.

OBJECTIVE: To examine the impact of sexuality education practices on adolescent birthrates while controlling for demographic characteristics and religious/political factors at a state level. DESIGN: Prospective cohort study. SETTING: Twenty-four states, from 1997 through 2005. PARTICIPANTS: Girls aged 15 to 17 years. MAIN EXPOSURE: The state sexuality education practices (ie, sexually transmitted disease prevention, pregnancy prevention, condom efficacy) for 1996 through 2004 from the Centers for Disease Control and Prevention School Health Profiles Survey. MAIN OUTCOME MEASURES: State birthrates for girls aged 15 to 17 years for 1997 through 2005 from the Centers for Disease Control and Prevention. RESULTS: In a longitudinal, unadjusted model, our findings provide evidence that increased sexuality education within school curricula is associated with lower adolescent birthrates (average sexuality education topics ß = -0.61; P = .001). However, the effect of sexuality education disappeared when taking into consideration the demographic characteristics, religiosity, and abortion policies of the state (average sexuality education topics ß = -0.12; P = .26). States with higher religiosity rankings and greater political conservatism had higher adolescent birthrates. CONCLUSIONS: The effects of sexuality education were constrained by state characteristics and do not independently explain the considerable variations in adolescent birthrates found across states. Our findings underscore the strong influence of state characteristics on adolescent birthrates above and beyond sexuality education, which must be considered when evaluating the efficacy of sexuality education programs.

Substance use and the risk for sexual intercourse with and without a history of teenage pregnancy among adolescent females.

OBJECTIVE: The present study examined the associations between initiation and intensity of substance use and with sexual experience with and without a history of teenage pregnancy. METHOD: Participants were high school females (weighted n = 3,451) who participated in the 1999-2003 Youth Risk Behavior Surveillance System, a cross-sectional, nationally representative survey. Multinomial multivariable logistic regression was used to assess the likelihood of being sexually experienced (but never pregnant) and teenage pregnancy (reference group: never had sexual intercourse) as a function of age at substance use initiation (i.e., age 12 or younger, 13-14 years of age, and age 15 or older) and intensity of substance use (i.e., nonuser, experimental/ new or nondaily, nonexperimental/daily user) for alcohol, cigarettes, and marijuana, while controlling for race/ethnicity, metropolitan location, symptoms of depression, and illegal drug availability at school. RESULTS: A major finding of our study is that substance use behaviors across each substance (alcohol, cigarettes, and marijuana) independently contributed to an increased risk in sexual intercourse experience with and without a history of teenage pregnancy (vs. nonsexually experienced females). A dose-response relationship was also observed between an increased likelihood of a teenage pregnancy and marijuana behaviors. Furthermore, the risk for teenage pregnancy was compounded for daily cigarette smokers who initiated use at age 12 or younger. CONCLUSIONS: Screening substance use behaviors can help to identify girls who may benefit from pregnancy prevention strategies. Targeting cigarette and marijuana behaviors as early as age 12 or younger may provide an added benefit. Prevention strategies should also consider the role of race above and beyond substance use behaviors.

Genetic vulnerability and susceptibility to substance dependence.

The development of substance dependence requires the initiation of substance use and the conversion from experimental use to established use before development of dependence. Numerous large twin studies have indicated a significant genetic contribution to this process. Genetic studies to date have been most successful at identifying genetic factors that influence the transition from regular use to dependence. The availability of large cohort samples for nicotine and alcohol dependence has resulted in significant progress being made in understanding at least some of the genetic contributions to these addictions. Fewer studies have replicated specific genetic contributions to illicit drug use, though it is clear that there is a strong genetic component involved here as well. Substance dependence can be thought of as a pharmacogenetic illness, and most likely hundreds and more probably thousands of genetic variants will be required to fully explain the genetic input to this disease.

Number of sexual partners and associations with initiation and intensity of substance use.

We dissected associations between initiation and intensity of substance use and number of sexual partners using pooled data from high school seniors (weighted n = 13,580) who participated in the 1999-2007 Youth Risk Behavior Surveillance System (YRBS), a cross-sectional, nationally representative survey. In multinomial multivariable logistic regressions, number of sexual partners steadily increased as substance use intensified from never use to experimental/new user to heavy use across all substances for both male and females. Severity of substance use is more closely related to, and thus a better indicator of, higher number of sexual partners than age of substance use onset.