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Background: This descriptive study identified latent classes of longitudinal marijuana use from ages 18 through 50 among a national sample; examined covariate associations with class membership regarding use/non-use, use intensity, and use duration; and described associations between identified latent classes and age 50 health outcomes.Methods: The study involved collection and primary analysis of data from 9831 individuals first surveyed as 12th graders in the national Monitoring the Future study and followed through modal age 50. Repeated measures latent class analysis was used to identify latent classes based on self-reported past 12-month marijuana use.Results: Seven latent classes of marijuana use from ages 18 to 50 were identified including Non-users (44%), two classes characterized by shorter-term use patterns (totaling 28%), and four classes characterized by longer-term moderate or heavy use (totaling 28%). Use reduction appeared particularly likely during early and late 20s. Gender, parental education, alcohol/cigarette use, religious commitment, and marital status differentiated use/non-use, use intensity, and use duration after high school. In non-causal models controlling for covariates, longer-term marijuana use classes (where use extended into the late 20s or beyond) were associated with significantly higher odds of negative health outcomes at age 50.Conclusions: Approximately 28% of the national sample reported longer-term moderate/heavy marijuana use, which was associated with negative health outcomes at age 50. The early and late 20s may be especially important periods for marijuana use prevention and intervention efforts, which may be strengthened by recognition of characteristics that appear to have significant associations with persistent use. [ABSTRACT FROM AUTHOR]

Objectives. To examine a potential increase in marijuana initiation among US college students as compared with their age peers not in college before and after 2013, a watershed year for increasing tolerance of marijuana use in the United States. Methods. Data come from the Monitoring the Future study, which has followed longitudinal panels drawn from annual nationally representative, baseline samples of 12th-grade students starting with the class of 1976. We studied panel members aged 19 to 22 years who had never used marijuana by 12th grade between 1977 and 2015. Results. College as a risk factor for marijuana initiation has increased significantly since 2013. The increased probability of past-year marijuana use for those enrolled versus not enrolled in college was 51% in 2015, 41% in 2014, and 31% in 2013; it averaged 17% to 22% from 1977 to 2012 among youths who had never used marijuana by 12th grade. Conclusions. College has grown as a risk factor for marijuana initiation since 2013. Public Health Implications. College students are in position to usher in new increase [ABSTRACT FROM AUTHOR]

Aims To test, among US students: (1) whether perceived harmfulness of marijuana has changed over time, (2) whether perceived harmfulness of marijuana changed post-passage of state medical marijuana laws (MML) compared with pre-passage; and (3) whether perceived harmfulness of marijuana statistically mediates and/or modifies the relation between MML and marijuana use as a function of grade level. Design Cross-sectional nationally representative surveys of US students, conducted annually, 1991-2014, in the Monitoring the Future study. Setting Surveys conducted in schools in all coterminous states; 21 states passed MML between 1996 and 2014. Participants The sample included 1 134 734 adolescents in 8th, 10th and 12th grades. Measurements State passage of MML; perceived harmfulness of marijuana use (perceiving great or moderate risk to health from smoking marijuana occasionally versus slight or no risk); and marijuana use (prior 30 days). Data were analyzed using time-varying multi-level regression modeling. Findings The perceived harmfulness of marijuana has decreased significantly since 1991 (from an estimated 84.0% in 1991 to 53.8% in 2014, P < 0.01) and, across time, perceived harmfulness was lower in states that passed MML [odds ratio (OR) = 0.86, 95% confidence interval (CI) = 0.75-0.97]. In states with MML, perceived harmfulness of marijuana increased among 8th graders after MML passage (OR = 1.21, 95% CI = 1.08-1.36), while marijuana use decreased (OR = 0.81, 95% CI = 0.72-0.92). Results were null for other grades, and for all grades combined. Increases in perceived harmfulness among 8th graders after MML passage was associated with ~33% of the decrease in use. When adolescents were stratified by perceived harmfulness, use in 8th graders decreased to a greater extent among those who perceived marijuana as harmful. Conclusions While perceived harmfulness of marijuana use appears to be decreasing nationally among adolescents in the United States, the passage of medical marijuana laws (MML) is associated with increases in perceived harmfulness among young adolescents and marijuana use has decreased among those who perceive marijuana to be harmful after passage of MML. [ABSTRACT FROM AUTHOR]

Background Effective policies that can reduce alcohol use behaviors and impaired driving among young people at a population level are needed. Graduated driver licensing ( GDL) laws increase the driving privileges of young novice drivers as they age and gain more driving experience. In this study, we seek to determine the effects of GDLs on risky driving behaviors of youth and to assess if GDLs have an unintended effect on underage drinking behaviors. Methods We utilized 2000 to 2013 data on 12th grade students from the Monitoring the Future ( MTF) study, an ongoing, annual national survey (since 1975) that studies the substance use behaviors of adolescents, as well as data on GDL laws obtained via the Insurance Institute for Highway Safety ( IIHS). We conducted a series of regular logistic regression models that included fixed effects for year and state, and adjusted for demographic characteristics, school characteristics, and other state alcohol policies. Results Total weighted sample size was 129,289 12th graders. Past month alcohol use and binge drinking (i.e., ≥5 drinks on one occasion) in the past 2 weeks were 45 and 26%, respectively. Seventeen percent of respondents reported riding with a driver who drank alcohol. Nearly 12% reported driving in the past 2 weeks after drinking alcohol, and 7% reported driving after binge drinking. Over half of the students lived in a state with a 'good' GDL law. The logistic regression models suggest a link between restrictive GDL policies and a reduction of alcohol use behaviors and risky driving behaviors among youth. Conclusions Our findings indicate that the effects of GDLs extend beyond driving-related risks and into other drinking-related behaviors that pose immediate or delayed health risks for young people. We speculate that GDLs may dictate social norms and expectations for youth risk behaviors, and should be maximized throughout the United States. [ABSTRACT FROM AUTHOR]

The article discusses a study that examines associations between sleep and substance use among middle and high school students in the U.S., trends in associations over time, and the comparative impact of select covariates on association strength. Topics covered include individual attributes linked with sleep and substance use, full multivariate correlation path analysis model, and trends in the frequency of getting at least seven hours of sleep among the students from 1991 to 2014.

Aims To measure changes over time in cigarette smoking uptake prevalence and timing during young adulthood (ages 19-26 years), and associations between time-invariant/-varying characteristics and uptake prevalence/timing. Design Discrete-time survival modeling of data collected from United States high school seniors (modal age 17/18) enrolled in successive graduating classes from 1976 to 2005 and participating in four follow-up surveys (to modal age 25/26). Setting The longitudinal component of the Monitoring the Future study. Participants A total of 10 758 individuals reporting no life-time smoking when first surveyed as high school seniors. Measurements Smoking uptake (any, experimental, occasional and regular); socio-demographic variables; marital, college and work status; time spent socializing. Findings The percentage of young adults moving from non-smoker to experimental smoking [slope estimate 0.11, standard error (SE) = 0.04, P = 0.005] or occasional smoking (slope estimate 0.17, SE = 0.03, P < 0.001) increased significantly across graduating classes; the percentage moving from non-smoker to regular smoker remained stable. All forms of smoking uptake were most likely to occur at age 19/20, but uptake prevalence at older ages increased over time [e.g. cohort year predicting occasional uptake at modal age 25/26 adjusted hazard odds ratio (AHOR) = 1.05, P = 0.002]. Time-invariant/-varying characteristics had unique associations with the timing of various forms of smoking uptake (e.g. at modal age 21/22, currently attending college increased occasional uptake risk (AHOR = 2.11, P < 0.001) but decreased regular uptake risk (AHOR = 0.69, P = 0.026). Conclusions Young adult occasional and experimental smoking uptake increased in the United States for non-smoking high school seniors graduating from 1976 to 2005. Smoking uptake for these cohorts remained most likely to occur at age 19/20, but prevalence of uptake at older ages increased. [ABSTRACT FROM AUTHOR]

ABSTRACT BACKGROUND The 2013-2014 school year involved preparation for implementing the new US Department of Agriculture ( USDA) competitive foods nutrition standards. An awareness of associations between commercial supplier involvement, food vending practices, and food vending item availability may assist schools in preparing for the new standards. METHODS Analyses used 2007-2012 questionnaire data from administrators of 814 middle and 801 high schools in the nationally representative Youth, Education, and Society study to examine prevalence of profit from and commercial involvement with vending machine food sales, and associations between such measures and food availability. RESULTS Profits for the school district were associated with decreased low-nutrient, energy-dense ( LNED) food availability and increased fruit/vegetable availability. Profits for the school and use of company suppliers were associated with increased LNED availability; company suppliers also were associated with decreased fruit/vegetable availability. Supplier 'say' in vending food selection was associated with increased LNED availability and decreased fruit/vegetable availability. CONCLUSIONS Results support (1) increased district involvement with school vending policies and practices, and (2) limited supplier 'say' as to what items are made available in student-accessed vending machines. Schools and districts should pay close attention to which food items replace vending machine LNED foods following implementation of the new nutrition standards. [ABSTRACT FROM AUTHOR]

Polysubstance use in adolescence is a known precursor to chronic substance misuse. Identifying risk factors for polysubstance use is necessary to inform its prevention. The present study examined the association of elevated levels of multiple mental health symptoms with adolescents' engagement in polysubstance use (past month use of alcohol, cigarettes, and marijuana). In a US national sample of 8th, 10th, and 12th grade students from Monitoring the Future surveys, we estimated probability of polysubstance use associated with high levels of depressive symptoms (DS), conduct problems (CP), or both. DS and CP, alone and particularly in combination, were associated with drastically elevated probability of polysubstance use. Adolescents with high levels of both DS and CP had the highest probability of polysubstance use. Among 8th and 10th graders, probability of polysubstance use associated with co-occurring mental health problems was significantly higher for girls than boys. [ABSTRACT FROM AUTHOR]

Aims To examine non-medical use of prescription opioids ( NMUPO) patterns during the transition from adolescence to adulthood, and assess individual characteristics and other substance use behaviors associated with longitudinal patterns of NMUPO. Design Nationally representative samples of high school seniors in the United States (wave 1: modal age 18 years) were followed longitudinally across three biennial follow-up waves (waves 2, 3 and 4: modal ages 19/20, 21/22 and 23/24 years). Setting Data were collected via self-administered questionnaires to high school seniors and young adults. Participants The longitudinal sample consisted of 27 268 individuals in 30 cohorts (high school senior years 1976-2005) who participated in all four waves. Measurements Self-reports of NMUPO and other substance use behaviors. Findings Approximately 11.6% [95% confidence interval ( CI) = 11.2%, 12.0%] of the sample reported past-year NMUPO in at least one of the four waves. Among those who reported past-year NMUPO in at least one wave, 69.0% (67.6%, 70.4%), 20.5% (19.3%, 21.7%), 7.8% (7.1%, 8.6%) and 2.7% (2.3%, 3.1%) reported NMUPO at one, two, three and four waves, respectively. Several wave 1 variables were associated with greater odds of multiple waves of NMUPO and individuals who reported more waves of NMUPO had greater odds of other substance use behaviors. Conclusions Although most non-medical use of prescription opioids among 18-year-olds in the United States appears to be non-continuing, approximately one-third of the sample reporting non-medical use of prescription opioids appear to continue use beyond age 18 and have elevated odds of other substance use behaviors at ages 23/24. [ABSTRACT FROM AUTHOR]

Objective: Young adults in the USA have one of the highest smoking prevalence rates of any age group, and young adulthood is a critical time period of targeting by the tobacco industry. The authors examined relationships between potential exposure to tobacco-related media campaigns from a variety of sponsors and 2-year smoking change measures among a longitudinal sample of US adults aged 20-30 years from 2001 to 2008. Methods: Self-report data were collected from a longitudinal sample of 12 931 US young adults from age 20 to 30. These data were merged with tobacco-related advertising exposure data from Nielsen Media Research. Two-year measures of change in smoking were regressed on advertising exposures. Results: Two-year smoking uptake was unrelated to advertising exposure. The odds of quitting among all smokers and reduction among daily smokers in the 2 years between the prior and current survey were positively related to anti-tobacco advertising, especially potential exposure levels of 104-155 ads over the past 24 months. Tobacco company advertising (including corporate image and anti-smoking) and pharmaceutical industry advertising were unrelated to quitting or reduction. Conclusion: Continued support for sustained, public health-based well-funded anti-tobacco media campaigns may help reduce tobacco use among young adults. [ABSTRACT FROM AUTHOR]