Protective factors relating to decreased risks of adolescent suicidal behaviour.

BACKGROUND: Suicide has been identified as one of the three leading causes of death in adolescents and young adults. No previous study in China has tested the association between protective factors and urban adolescents' suicidal behaviours. In this study we tested the hypothesis that suicidal behaviours would be associated with multiple protective factors. METHODS: A stratified random of 9015 students from 100 junior middle schools in Beijing, Hangzhou, Wuhan and Urumqi completed the Chinese version of Global School-Based Student Health Survey. RESULTS: Overall, 17.4% of students had seriously considered attempting suicide, and 8.1% had made a specific plan to attempt suicide during the 12 months preceding the survey. The students in Wuhan (18.7%) and Urumqi (20.8%) cities were significantly more likely than students in Beijing (14.4%) and Hangzhou (14.4%) to have suicidal ideation (chi2 = 45.9, P < 0.001). Female students were significantly more likely than male students to have suicidal ideation and have made suicide attempts [odds ratio (OR) = 1.4, P < 0.001]. Results indicated that the rates of suicidal ideation and suicide attempts increased with age (OR = 1.44, P < 0.001). Multivariate logistic regression models showed that suicide risk tended to decrease significantly when 'days of missed classes or school without permission were less than one', and when students thought students in their school were kind and helpful most of the time or always', 'parents or guardians checked to see if homework was done most of the time or always', 'parents or guardians understood their problems and worries most of the time or always' and 'parents or guardians really know what they are doing with their free time most of the time or always'. CONCLUSIONS: Adolescent suicide behaviour should be a serious problem. Measures can be taken to prevent suicide by observing the factors significantly linked to suicidal behaviour. Steps can then be taken to identify adolescents who have serious suicidal ideation so that intervention can be taken to reduce the suicidal rate.

Competitive foods and beverages available for purchase in secondary schools--selected sites, United States, 2004.

School Health Profiles is conducted biennially to assess characteristics of school health programs. State and local departments of education and health select either all public secondary schools within their jurisdictions or a systematic, equal-probability sample of public secondary schools to participate in School Health Profiles. At each school, the principal and lead health education teacher were sent questionnaires to be self-administered and returned to the state or local agency conducting the survey. In 2004, a total of 27 states and 11 large urban school districts obtained weighted data from their survey of principals. The findings in this report indicate that the majority of secondary schools in 27 states and 11 large urban school districts allow students to purchase snack foods or beverages from vending machines or at the school store, canteen, or snack bar. The types of competitive foods and beverages available for purchase varied across states and large urban school districts. Overall, fruits or vegetables were less likely to be available for purchase than the other types of foods or beverages. Bottled water and soft drinks, sports drinks, or fruit drinks that are not 100% juice were most likely to be available for purchase.

Prevalence of health-related behaviors among alternative high school students as compared with students attending regular high schools.

PURPOSE: To provide national data on health-risk behaviors of students attending alternative high schools and compare the prevalence of these risk behaviors with data from the 1997 national Youth Risk Behavior Survey. METHODS: The national Youth Risk Behavior Survey uses a three-stage cluster sampling design. Data were collected from 8918 students in alternative high schools in 1998 (ALT-YRBS) and 16,262 students in regular high schools in 1997 (YRBS). The health-risk behaviors addressed include behaviors that contribute to unintentional injuries and violence, tobacco use, alcohol and other drug use, sexual behaviors, unhealthy dietary behaviors, and physical inactivity. A weighing factor was applied to each student record to adjust for nonresponse and varying probabilities of selection. SUDAAN was used to compute 95% confidence intervals, which were considered significant if the 95% confidence intervals did not overlap. RESULTS: Students attending alternative high schools were at significantly greater risk than students in regular high schools for violence-related injury; suicide; human immunodeficiency virus infection or other sexually transmitted diseases; pregnancy; and development of chronic disease related to tobacco use, unhealthy dieting practices, and lack of vigorous activity. CONCLUSIONS: Many students in alternative high schools are at risk for both acute and chronic health problems. Because these youth are still in a school setting, alternative high schools are in a unique position to provide programs to help decrease the prevalence of risk-taking behaviors.

Sexually antagonistic cytonuclear fitness interactions in Drosophila melanogaster.

Theoretical and empirical studies have shown that selection cannot maintain a joint nuclear-cytoplasmic polymorphism within a population except under restrictive conditions of frequency-dependent or sex-specific selection. These conclusions are based on fitness interactions between a diploid autosomal locus and a haploid cytoplasmic locus. We develop a model of joint transmission of X chromosomes and cytoplasms and through simulation show that nuclear-cytoplasmic polymorphisms can be maintained by selection on X-cytoplasm interactions. We test aspects of the model with a "diallel" experiment analyzing fitness interactions between pairwise combinations of X chromosomes and cytoplasms from wild strains of Drosophila melanogaster. Contrary to earlier autosomal studies, significant fitness interactions between X chromosomes and cytoplasms are detected among strains from within populations. The experiment further demonstrates significant sex-by-genotype interactions for mtDNA haplotype, cytoplasms, and X chromosomes. These interactions are sexually antagonistic--i.e., the "good" cytoplasms in females are "bad" in males--analogous to crossing reaction norms. The presence or absence of Wolbachia did not alter the significance of the fitness effects involving X chromosomes and cytoplasms but tended to reduce the significance of mtDNA fitness effects. The negative fitness correlations between the sexes demonstrated in our empirical study are consistent with the conditions that maintain cytoplasmic polymorphism in simulations. Our results suggest that fitness interactions with the sex chromosomes may account for some proportion of cytoplasmic variation in natural populations. Sexually antagonistic selection or reciprocally matched fitness effects of nuclear-cytoplasmic genotypes may be important components of cytonuclear fitness variation and have implications for mitochondrial disease phenotypes that differ between the sexes.

Recent trends in participation in physical education among US high school students.

To examine recent trends in physical education (PE) enrollment, daily attendance in PE, and being physically active in PE among high school students in the United States, this study analyzed data from the 1991, 1993, 1995, and 1997 national school-based Youth Risk Behavior Surveys (n = 55,734). Logistic regression analyses were conducted to test for significant linear time trends among the total student population and demographic subgroups (gender, race/ethnicity, and grade). Although PE enrollment in the total student population did not change from 1991 (48.9%) to 1997 (48.8%), the prevalence of students who attended PE daily, and the prevalence of students who were physically active > 20 minutes in an average PE class both decreased significantly among nearly all demographic subgroups. The prevalence of students who were physically active > 20 minutes in daily PE classes decreased from 34.2% in 1991 to 21.7% in 1997 (p < 0.001). To reverse current trends, high schools should implement daily PE classes that emphasize participation in lifelong health-related physical activity for all students.

The Youth Risk Behavior Surveillance System: measuring health-risk behaviors.

OBJECTIVE: To measure priority health-riskbehaviors among youth. METHODS: The Youth Risk Behavior Surveillance System (YRBSS) monitors priority health-risk behaviors among youth. RESULTS: In 1999, many high school students practiced behaviors that contribute to leading health problems--16.4% rarely or never wore safety belts and, during the past 30 days, 17.3% carried a weapon, 34.8% smoked cigarettes, and 26.7% used marijuana. Also, 49.9% had had sexual intercourse. One quarter (26.0%) were at risk for becoming overweight or were overweight. CONCLUSION: YRBSS data are used to improve policies and programs to reduce priority health-risk behaviors among youth.

Initial sequencing and analysis of the human genome.

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

Gene flow versus local adaptation in the northern acorn barnacle, Semibalanus balanoides: insights from mitochondrial DNA variation.

In reciprocal transplant experiments, Bertness and Gaines (1993) found that Semibalanus balanoides juveniles that had settled in an upper Narragansett Bay estuary survived better in that estuary that did juveniles from coastal localities. The observed pattern of survivorship led to the claim that local adaptation may result from a combination of limited gene flow between and strong selection within these habitats. Here we test the hypothesis that limited gene flow has led to habitat-specific population differentiation using sequence and restriction fragment length polymorphism analyses of the mitochondrial DNA D-loop region of S. balanoides. Samples were analyzed from replicated coastal and estuary localities in both Narragansett Bay, Rhode Island, and Damariscotta River, Maine. The patterns of F(ST) indicate that gene flow between coast and estuary is extensive (Nm > 100) and is not lower in the estuary with lower flushing rates (Narragansett Bay). Given the high estimate of genetic exchange, adaptations for unpredictable environments seem more likely than local adaptation in this species because loci that respond to selection in one generation are essentially homogenized by the next seasons' settlement. Nevertheless, these estimates of neutral gene flow can help identify the strength of selection necessary for local adaptation to accumulate in Semibalanus.

Prevalence of health risk behaviors among Asian American/Pacific Islander high school students.

PURPOSE: [corrected] To compare the prevalence of selected risk behaviors among Asian American/Pacific Islander (AAPI) students and white, black, and Hispanic high school students in the United States. METHODS: The national Youth Risk Behavior Survey conducted in 1991, 1993, 1995, and 1997 by the Centers for Disease Control and Prevention produced nationally representative samples of students in grades 9 through 12 in all 50 states and the District of Columbia. To generate a sufficient sample of AAPI students, data from these four surveys were combined into one dataset yielding a total sample size of 55, 734 students. RESULTS: In the month preceding the survey, AAPI students were significantly less likely than black, Hispanic, or white students to have drunk alcohol or used marijuana. AAPI students also were significantly less likely than white, black, or Hispanic students to have had sexual intercourse; however, once sexually active, AAPI students were as likely as other racial or ethnic groups to have used alcohol or drugs at last intercourse or to have used a condom at last intercourse. AAPI students were significantly less likely than white, black, or Hispanic students to have carried a weapon or fought but were as likely as any of the other groups to have attempted suicide. CONCLUSIONS: A substantial percentage of AAPI students engage in risk behaviors that can affect their current and future health. Prevention programs should address the risks faced by AAPI students using culturally sensitive strategies and materials. More studies are needed to understand the comparative prevalence of various risk behaviors among AAPI subgroups.

Surveillance for characteristics of health education among secondary schools--school health education profiles, 1998.

PROBLEM/CONDITION: School health education (e.g., classroom instruction) is an essential component of school health programs; such education promotes the health of youth and improves overall public health. REPORTING PERIOD: February-May 1998. DESCRIPTION OF SYSTEM: The School Health Education Profiles monitor characteristics of health education in middle or junior high schools and senior high schools in the United States. The Profiles are school-based surveys conducted by state and local education agencies. This report summarizes results from 36 state surveys and 10 local surveys conducted among representative samples of school principals and lead health education teachers. The lead health education teacher coordinates health education policies and programs within a middle/junior high school or senior high school. RESULTS: During the study period, most schools in states and cities that conducted Profiles required health education in grades 6-12. Of these, a median of 91.0% of schools in states and 86.2% of schools in cities taught a separate health education course. The median percentage of schools in each state and city that tried to increase student knowledge in selected topics (i.e., prevention of tobacco use, alcohol and other drug use, pregnancy, human immunodeficiency virus [HIV] infection, other sexually transmitted diseases, violence, or suicide; dietary behaviors and nutrition; and physical activity and fitness) was >73% for each of these topics. The median percentage of schools with a health education teacher who coordinated health education was 38.7% across states and 37.6% across cities. A median of 41.8% of schools across states and a median of 31.0% of schools across cities had a lead health education teacher with professional preparation in health and physical education, whereas a median of 6.0% of schools across states and a median of 5.5% of schools across cities had a lead health education teacher with professional preparation in health education only. A median of 19.3% of schools across states and 21.2% of schools across cities had a school health advisory council. The median percentage of schools with a written school or school district policy on HIV-infected students or school staff members was 69.7% across states and 84.4% across cities. INTERPRETATION: Many middle/junior high schools and senior high schools require health education to help provide students with knowledge and skills needed for adoption of a healthy lifestyle. However, these schools might not be covering all important topic areas or skills sufficiently. The number of lead health education teachers who are academically prepared in health education and the number of schools with school health advisory councils needs to increase. PUBLIC HEALTH ACTION: The Profiles data are used by state and local education officials to improve school health education.

Youth Risk Behavior Surveillance--United States, 1999. State and local YRBSS Coordinators.

Priority health-risk behaviors, which contribute to the leading causes of mortality and morbidity among youth and adults, often are established during youth, extend into adulthood, are interrelated, and are preventable. The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health-risk behaviors among youth and young adults--behaviors that contribute to unintentional and intentional injuries; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs) (including human immunodeficiency virus [HIV] infection); unhealthy dietary behaviors; and physical inactivity. The YRBSS includes a national school-based survey conducted by CDC as well as state, territorial, and local school-based surveys conducted by education and health agencies. This report summarizes results from the national survey, 33 state surveys, and 16 local surveys conducted among high school students during February through May 1999. In the United States, approximately three fourths of all deaths among persons aged 10-24 years result from only four causes: motor-vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1999 national Youth Risk Behavior Survey demonstrate that numerous high school students engage in behaviors that increase their likelihood of death from these four causes--16.4% had rarely or never worn a seat belt; during the 30 days preceding the survey, 33.1% had ridden with a driver who had been drinking alcohol; 17.3% had carried a weapon during the 30 days preceding the survey; 50.0% had drunk alcohol during the 30 days preceding the survey; 26.7% had used marijuana during the 30 days preceding the survey; and 7.8% had attempted suicide during the 12 months preceding the survey. Substantial morbidity and social problems among young persons also result from unintended pregnancies and STDs, including HIV infection. In 1999, nationwide, 49.9% of high school students had ever had sexual intercourse; 42.0% of sexually active students had not used a condom at last sexual intercourse; and 1.8% had ever injected an illegal drug. Two thirds of all deaths among persons aged > or = 25 years result from only two causes--cardiovascular disease and cancer. The majority of risk behaviors associated with these two causes of death are initiated during adolescence. In 1999, 34.8% of high school students had smoked cigarettes during the 30 days preceding the survey; 76.1% had not eaten > or = 5 servings/day of fruits and vegetables during the 7 days preceding the survey; 16.0% were at risk for becoming overweight; and 70.9% did not attend physical education class daily. These YRBSS data are already being used by health and education officials at national, state, and local levels to analyze and improve policies and programs to reduce priority health-risk behaviors among youth. The YRBSS data also are being used to measure progress toward achieving 16 national health objectives for 2010 and 3 of the 10 leading health indicators.

Use of birth control pills, condoms, and withdrawal among U.S. high school students.

PURPOSE: To examine the use of contraception at last sexual intercourse among currently sexually active adolescents. METHODS: We analyzed data from national school-based Youth Risk Behavior Surveys (YRBS) conducted in 1991, 1993, 1995, and 1997. The YRBS is a self-administered, anonymous survey which uses a national probability sample of U.S. students in public and private schools from grades 9 through 12. RESULTS: From 1991 to 1997, condom use significantly increased (from 46% to 57%), birth control pill use decreased (from 21% to 17%), and use of withdrawal significantly decreased (from 18% to 13%). In 1997, although more students were using condoms, 13% reported using withdrawal and 15% reported using no method to prevent pregnancy at last sexual intercourse. In 1997, condom use among females was significantly lower in the 9th grade than in the 12th grade (p <.001), whereas birth control pill use was higher (p <.001) and use of withdrawal remained stable. Among males, condom use and withdrawal use remained stable from 9th to 12th grade, whereas birth control pill use by their partner increased (p <.001). CONCLUSIONS: Inadequate contraceptive use among sexually active adolescents continues to be a major public health problem in the United States. For young people who will not remain sexually abstinent, families, health care providers, schools, and other influential societal institutions should promote the correct and continued use of condoms as essential protection against sexually transmitted diseases and human immunodeficiency virus infection.

Contextual influences on school provision of health services.

PURPOSE: To examine contextual factors that may facilitate or impede the provision of school health services. METHODS: Using a composite database derived primarily from the National Longitudinal Study of Adolescent Health, we used logistic regression to examine how selected characteristics of communities, schools, and state-level policies are related to the provision of specific health services by high schools. RESULTS: Schools whose students experienced more health risks were generally more likely to provide related services than schools whose students experienced fewer risks. State policies and requirements for health-related programs and services were associated with greater school-based provision of services. Availability of health care services within the community was associated with a reduced likelihood that schools provided similar services on-site; however, for some health services, the reverse was true. In general, more affluent communities were more likely to provide school health services than less affluent communities. Public schools were more likely to offer health services than private schools. CONCLUSIONS: Certain characteristics of communities, schools, and state-level policies are associated with the provision of school health services. These contextual factors appear to operate by creating a demand for services and by creating the opportunity for schools to provide health services.

Physical activity, food choice, and weight management goals and practices among US college students.

INTRODUCTION: Physical activity and a healthy diet have been recommended to help reverse the increasing prevalence of overweight among adolescents and adults in the United States. METHODS: Data is from the 1995 National College Health Risk Behavior Survey. A representative sample of US undergraduate college students (n = 4609) were analyzed to examine associations of physical activity and food choice with weight management goals and practices. RESULTS: Based on self-reported height and weight, 35% of students were overweight or obese (body mass index > or = 25.0). Nearly half (46%) of all students reported they were trying to lose weight. Female students were less likely than male students to be overweight, but more likely to be trying to lose weight. Among female and male students, using logistic regression to control for demographics, trying to lose weight was associated with participation in vigorous physical activity and strengthening exercises, and consumption of < or = 2 servings/ day of high-fat foods. Female and male students who reported using exercise to lose weight or to keep from gaining weight were more likely than those who did not to participate in vigorous, strengthening, and moderate physical activity, and were more likely to eat > or = 5 servings/day of fruits and vegetables and < or = 2 servings/day of high-fat foods. Among students who were trying to lose weight, only 54% of females and 41% of males used both exercise and diet for weight control. CONCLUSION: Colleges should implement programs to increase student awareness of healthy weight management methods and the importance of physical activity combined with a healthy diet.

Youth risk behavior surveillance. National Alternative High School Youth Risk Behavior Survey, United States, 1998.

Alternative high schools serve approximately 280,000 students nationwide who are at high risk for failing or dropping out of regular high school or who have been expelled from regular high school because of illegal activity or behavioral problems. Such settings provide important opportunities for delivering health promotion education and services to these youth and young adults. However, before this survey, the prevalence of health-risk behaviors among students attending alternative high schools nationwide was unknown. The Youth Risk Behavior Surveillance System (YRBSS) monitors the following six categories of priority health-risk behaviors among youth and young adults: behaviors that contribute to unintentional and intentional injuries; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs) (including human immunodeficiency virus [HIV] infection); unhealthy dietary behaviors; and physical inactivity. The national Alternative High School Youth Risk Behavior Survey (ALT-YRBS) is one component of the YRBSS; it was conducted in 1998 to measure priority health-risk behaviors among students at alternative high schools. The 1998 ALT-YRBS used a three-stage cluster sample design to produce a nationally representative sample of students in grades 9-12 in the United States who attend alternative high schools. The school response rate was 81.0%, and the student response rate was 81.9%, resulting in an overall response rate of 66.3%. This report summarizes results from the 1998 ALT-YRBS. The reporting period is February-May 1998. In the United States, 73.6% of all deaths among youth and young adults aged 10-24 years results from only four causes--motor vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1998 ALT-YRBS demonstrate that many students at alternative high schools engage in behaviors that increase their likelihood of death from these four causes. During the 30 days preceding the survey, 51.9% had ridden with a driver who had been drinking alcohol, 25.1% had driven a vehicle after drinking alcohol, 32.9% had carried a weapon, 64.5% had drunk alcohol, and 53.0% had used marijuana. During the 12 months preceding the survey, 15.7% had attempted suicide, and 29.0% had rarely or never worn a seat belt. Substantial morbidity among school-aged youth and young adults also results from unintended pregnancies and STDs, including HIV infection. ALT-YRBS results indicate that in 1998, a total of 87.8% of students at alternative high schools had had sexual intercourse, 54.1% of sexually active students had not used a condom at last sexual intercourse, and 5.7% had ever injected an illegal drug. Among adults aged > or = 25 years, 66.5% of all deaths result from two causes--cardiovascular disease and cancer. Most risk behaviors associated with these causes of death are initiated during adolescence. In 1998, a total of 64.1% of students at alternative high schools had smoked cigarettes during the 30 days preceding the survey, 38.3% had smoked a cigar during the 30 days preceding the survey, 71.2% had not eaten > or = 5 servings of fruits and vegetables during the day preceding the survey, and 81.0% had not attended physical education (PE) class daily. Comparing ALT-YRBS results with 1997 national YRBS results demonstrates that the prevalence of most risk behaviors is higher among students attending alternative high schools compared with students at regular high schools. Some risk behaviors are more common among certain sex and racial/ethnic subgroups of students. ALT-YRBS data can be used nationwide by health and education officials to improve policies and programs designed to reduce risk behaviors associated with the leading causes of morbidity and mortality among students attending alternative high schools.

Youth risk behavior surveillance--United States, 1999.

PROBLEM/CONDITION: Priority health-risk behaviors, which contribute to the leading causes of mortality and morbidity among youth and adults, often are established during youth, extend into adulthood, are interrelated, and are preventable. REPORTING PERIOD: February-May 1999. DESCRIPTION OF THE SYSTEM: The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health-risk behaviors among youth and young adults --behaviors that contribute to unintentional and intentional injuries; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs) (including human immunodeficiency virus [HIV] infection); unhealthy dietary behaviors; and physical inactivity. The YRBSS includes a national school-based survey conducted by CDC as well as state, territorial, and local school-based surveys conducted by education and health agencies. This report summarizes results from the national survey, 33 state surveys, and 16 local surveys conducted among high school students during February-May 1999. RESULTS AND INTERPRETATION: In the United States, approximately three fourths of all deaths among persons aged 10-24 years result from only four causes: motor-vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1999 national Youth Risk Behavior Survey demonstrate that numerous high school students engage in behaviors that increase their likelihood of death from these four causes--16.4% had rarely or never worn a seat belt; during the 30 days preceding the survey, 33.1% had ridden with a driver who had been drinking alcohol; 17.3% had carried a weapon during the 30 days preceding the survey; 50.0% had drunk alcohol during the 30 days preceding the survey; 26.7% had used marijuana during the 30 days preceding the survey; and 7.8% had attempted suicide during the 12 months preceding the survey. Substantial morbidity and social problems among young persons also result from unintended pregnancies and STDs, including HIV infection. In 1999, nationwide, 49.9% of high school students had ever had sexual intercourse; 42.0% of sexually active students had not used a condom at last sexual intercourse; and 1.8% had ever injected an illegal drug. Two thirds of all deaths among persons aged > or = 25 years result from only two causes--cardiovascular disease and cancer. The majority of risk behaviors associated with these two causes of death are initiated during adolescence. In 1999, 34.8% of high school students had smoked cigarettes during the 30 days preceding the survey; 76.1% had not eaten > or = 5 servings/day of fruits and vegetables during the 7 days preceding the survey; 16.0% were at risk for becoming overweight; and 70.9% did not attend physical education class daily. ACTIONS TAKEN: These YRBSS data are already being used by health and education officials at national, state, and local levelsto analyze and improve policies and programs to reduce priority health-risk behaviors among youth. The YRBSS data also are being used to measure progress toward achieving 16 national health objectives for 2010 and 3 of the 10 leading health indicators.

Initiation of cigarette smoking and subsequent smoking behavior among U.S. high school students.

BACKGROUND: Most adult smokers report trying their first cigarette before age 18 years. Understanding the impact of smoking initiation at young ages may help public health policy makers and practitioners improve strategies to prevent or delay adolescent cigarette smoking. METHODS: This paper examined age of initiation of cigarette smoking and subsequent patterns of smoking among U.S. high school students 16 years of age and older (N = 13,858). We used data from the 1991-1997 national Youth Risk Behavior Surveys, conducted by the Centers for Disease Control and Prevention. RESULTS: The majority of students 16 years of age and older (60.4%) reported ever having smoked a whole cigarette, and 11.1% initiated smoking at age 10 years or younger. Age of smoking initiation was significantly related to current frequent smoking, daily smoking, and whether students had ever smoked daily. A younger age of smoking initiation was associated with smoking more cigarettes per day than was initiating at an older age. CONCLUSIONS: Delaying the onset of smoking may affect the likelihood of becoming addicted to nicotine and smoking heavily. For students who are already addicted to nicotine, smoking cessation programs are needed.