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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]

Objective: The study describes the most common reasons for using vaporizers (such as e-cigarettes) among US adolescents and investigates how reasons for use differ by grade, lifetime cigarette use, frequency of vaporizer use, gender, race/ethnicity, and parent education.Method: Data were collected from 4066 students in the 8th, 10th, and 12th grades in 2015 as part of the Monitoring the Future study, a cross-sectional and nationally representative US survey.Results: Common reasons for vaporizer use reported by respondents who had ever used a vaporizer were experimentation (53.0%), taste (37.2%), boredom (23.5%), having a good time (22.4%), and relaxation (21.6%). Reasons differed little across grades or parent education; reasons differed by lifetime use of regular cigarettes, frequency of vaping, gender, and race/ethnicity.Conclusions: Overall, results suggest that decisions to vape are based on curiosity, taste, and pleasure, rather than for reasons such as quitting regular cigarettes or substituting for regular cigarette smoking. [ABSTRACT FROM AUTHOR]

Aims: Preference for risky activities is an important developmentally graded predictor of substance use. Population-level trends in adolescent risk preference, as well as the way in which risk preference may be a conduit to risk behavior, have never been documented. The present study examines population-level trends in risk preference among U.S. high school seniors for the 36 years from 1976 to 2011, as well as trends in the association between risk preference and substance use and other problem behaviors.Methods: Data were drawn from yearly nationally representative cross-sectional surveys of US high school seniors (N=91,860). Risk preference was measured consistently with two items. Marijuana and cocaine use, binge drinking, and conduct problems were assessed. Trends were tested using JoinPoint software.Results: The mean level of reported risk preference among US 12th graders has increased over time, especially in the 1980s. For example, the proportion of high school females who reported enjoying activities that were "a little dangerous" more than doubled, from 4.9% in 1976 to 10.8% in 1988. While risk preference reports among adolescent males leveled off in 1992, risk preference reports among females show a continued positive overall slope through 2011. The magnitude of the association between risk preference and marijuana use has increased over time.Conclusions: Reported preference for risky activities has increased among adolescents in the US, especially among young women. Reported risk preference is increasingly associated with a higher use of marijuana. Our findings argue for the importance of placing risk preference within a multi-level framework that attends to historical variation. [ABSTRACT FROM AUTHOR]