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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]

Background: Little is known regarding what sociodemographic characteristics and reasons for use are associated with adolescent solitary alcohol and marijuana use.Methods: Data from 7845 12th grade students participating in the nationally-representative Monitoring the Future study from 2015 to 2021 were used to examine cross-sectional associations between sociodemographics, heavy drinking/marijuana use, reasons for use, and past 12-month solitary alcohol or marijuana use among past 12-month users. Historical trends and possible differences related to the COVID-19 pandemic also were examined.Results: Solitary use prevalence increased from 2015 to 2021 with no evidence of significant COVID-19 deviations. In 2021, solitary alcohol use was reported by 32.1% (SE 3.01) and solitary marijuana use by 55.8% (4.72) of those reporting past 12-month use. Common and substance-specific sociodemographic risk factors were observed. Binge drinking was associated with solitary alcohol use; frequent marijuana use was associated with solitary marijuana use. Reasons for use related to coping with negative affect were associated with solitary use. Compulsive use reasons were more strongly associated with solitary alcohol than marijuana use. Drinking to have a good time with friends was negatively associated with solitary alcohol use but this association was not seen for solitary marijuana use.Conclusions: The percentage of adolescents who use alcohol or marijuana when they were alone has increased among those who report using each substance. Associations between solitary use and (a) higher levels of consumption and (b) coping with negative affect highlight the importance of solitary use as a risk indicator. [ABSTRACT FROM AUTHOR]

Background: Simultaneous alcohol and marijuana (SAM) use raises significant concern due to the potential for additive or interactive psychopharmacological effects. However, no nationally representative studies are available that document prevalence, trends, or related factors in US youth SAM use.Methods: Nationally representative cross-sectional samples of 12th grade students surveyed in the Monitoring the Future project from 1976 to 2011 provided data on SAM use. Analyses were conducted in 2012.Results: In 2011, 23% of all U.S. high school seniors reported any SAM use. Among seniors reporting any past 12-month marijuana use, 62% reported any SAM use and 13% reported SAM use most or every time they used marijuana. SAM use consistently followed trends for past 30-day alcohol use over time. SAM use showed significant variation by psychosocial and demographic characteristics and was strongly associated with higher substance use levels, but occurred across the substance use spectrum. Certain reasons for alcohol or marijuana use (to increase effects of another drug; I'm hooked) and situations of alcohol or marijuana use (park/beach, car, party) were strongly associated with SAM use.Conclusions: A sizable proportion of US high school seniors reported SAM use, and it appeared to occur frequently in social use situations that could impact both the public as well as youth drug users. SAM use appears to be a complex behavior that is incidental to general substance use patterns as well as associated with (a) specific simultaneous reasons (or expectancies), and (b) heavy substance use and perceived dependence, especially on alcohol. [ABSTRACT FROM AUTHOR]

Abstract: Background: Simultaneous alcohol and marijuana (SAM) use raises significant concern due to the potential for additive or interactive psychopharmacological effects. However, no nationally representative studies are available that document prevalence, trends, or related factors in US youth SAM use. Methods: Nationally representative cross-sectional samples of 12th grade students surveyed in the Monitoring the Future project from 1976 to 2011 provided data on SAM use. Analyses were conducted in 2012. Results: In 2011, 23% of all US high school seniors reported any SAM use. Among seniors reporting any past 12-month marijuana use, 62% reported any SAM use and 13% reported SAM use most or every time they used marijuana. SAM use consistently followed trends for past 30-day alcohol use over time. SAM use showed significant variation by psychosocial and demographic characteristics and was strongly associated with higher substance use levels, but occurred across the substance use spectrum. Certain reasons for alcohol or marijuana use (to increase effects of another drug; I’m hooked) and situations of alcohol or marijuana use (park/beach, car, party) were strongly associated with SAM use. Conclusions: A sizable proportion of US high school seniors reported SAM use, and it appeared to occur frequently in social use situations that could impact both the public as well as youth drug users. SAM use appears to be a complex behavior that is incidental to general substance use patterns as well as associated with (a) specific simultaneous reasons (or expectancies), and (b) heavy substance use and perceived dependence, especially on alcohol. [Copyright &y& Elsevier]

Background: This study examines the extent to which the developmental pattern of frequent marijuana use prevalence from ages 18 to 30 (overall and by gender) has varied across historical time (cohort groups) using data from a national sample of US young adults.Methods: Self-reported data on frequent marijuana use (use on 20+ occasions in the past 30 days) from modal ages 18 to 30 were obtained from 58,059 individuals from 29 sequential cohorts (graduating high school classes of 1976-2004) participating in the Monitoring the Future study. Time-varying effect modeling was used to model cohort group differences in developmental patterns of frequent use overall and by gender.Results: Developmental patterns of frequent marijuana use prevalence varied meaningfully across cohort groups. Frequent use at age 18 differed significantly across cohort groups as expected based on national data. Among earlier cohort groups (reaching age 30 during 1987-2008), developmental patterns converged by age 30 to relatively low frequent marijuana use prevalence. In contrast, among cohort groups reaching age 30 during 2008-2016, frequent marijuana use at age 30 was significantly higher than all previous cohort groups. Observed cohort differences did not vary significantly by gender.Conclusions: Cross-cohort convergence in developmental patterns of frequent marijuana use prevalence by age 30 was not observed among recent cohort groups, among whom age 30 frequent marijuana use prevalence was at the highest levels observed since the study began. Higher frequent marijuana use prevalence in late young adulthood has meaningful health risk and service provision implications. [ABSTRACT FROM AUTHOR]

Background: More United States adolescents now report high-frequency marijuana use than similar use levels of alcohol or tobacco. Increased high-frequency use raises questions such as (a) is frequent use likelihood growing among adolescents who experiment with use? (b) Is such change observed equally across sex and racial/ethnic subgroups? (c) Have sociodemographic and other covariate associations with frequent use changed over time?Methods: Data were obtained from 649,505 12th grade students participating in the cross-sectional, nationally-representative Monitoring the Future study from 1976 to 2019. Historical trends were modeled for any and frequent (20+ occasions) past 30-day marijuana use among all students and lifetime users, and lifetime user sex and racial/ethnic subgroups. Multivariable logistic regression estimates from 1989 to 1993 (lowest prevalence years) versus 2015-2019 (most recent years) were compared to examine covariate association changes with frequent use.Results: Among all students, recent linear trends in any and frequent marijuana use were not significantly different from zero (0.023 [SE 0.156] and 0.036 [0.073], respectively); frequent use among lifetime users increased (0.233 [0.107], p = 0.048). Among lifetime users, the increase was stronger for male than female students, and for minority versus White students. Significant association changes with race/ethnicity, parental education, and perceived risk were observed.Conclusions: The proportion of adolescent lifetime marijuana users reporting current frequent marijuana use increased, and is now at near-record levels. Increases were particularly strong among males and minority students. There appears to be an increasing likelihood that adolescents who experiment with marijuana use may progress to frequent 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]

Background National trends in adolescent’s marijuana risk perceptions are traditionally used as a predictor of concurrent and future trends in adolescent marijuana use. We test the validity of this practice during a time of rapid marijuana policy change. Methods Two repeated cross-sectional U.S. nationally-representative surveys of 8th, 10th, and 12th-graders: Monitoring the Future (MTF) (1991–2015; N = 1,181,692) and National Survey on Drug Use and Health (NSDUH) (2002–2014; N = 113,317). We examined trends in the year-to-year prevalence of perceiving no risk of harm in using marijuana regularly, and prevalence of regular marijuana use within the previous month. A piecewise linear regression model tested for a change in the relationship between trends. Similar analyses examined any past-month use and controlled for demographic characteristics. Results Among MTF 12th-graders, the prevalence of regular marijuana use and risk perceptions changed similarly between 1991 and 2006 but diverged sharply afterward. The prevalence of regular marijuana use increased by ∼1 percentage point to 6.03% by 2015. In contrast, the proportion of 12th-graders that perceived marijuana as posing no risk increased over 11 percentage points to 21.39%. A similar divergence was found among NSDUH 12th-graders and other grades, for any past month marijuana use, and when controlling demographic characteristics. Conclusions An increase in adolescent marijuana use has not accompanied recent rapid decreases in marijuana risk perceptions. Policy makers may consider broader prevention strategies in addition to targeting marijuana risk perceptions. Further monitoring of predictors of marijuana use trends is needed as states legalize recreational marijuana use. [ABSTRACT FROM AUTHOR]

Background: National trends in adolescent's marijuana risk perceptions are traditionally used as a predictor of concurrent and future trends in adolescent marijuana use. We test the validity of this practice during a time of rapid marijuana policy change.Methods: Two repeated cross-sectional U.S. nationally-representative surveys of 8th, 10th, and 12th-graders: Monitoring the Future (MTF) (1991-2015; N = 1,181,692) and National Survey on Drug Use and Health (NSDUH) (2002-2014; N = 113,317). We examined trends in the year-to-year prevalence of perceiving no risk of harm in using marijuana regularly, and prevalence of regular marijuana use within the previous month. A piecewise linear regression model tested for a change in the relationship between trends. Similar analyses examined any past-month use and controlled for demographic characteristics.Results: Among MTF 12th-graders, the prevalence of regular marijuana use and risk perceptions changed similarly between 1991 and 2006 but diverged sharply afterward. The prevalence of regular marijuana use increased by ∼1 percentage point to 6.03% by 2015. In contrast, the proportion of 12th-graders that perceived marijuana as posing no risk increased over 11 percentage points to 21.39%. A similar divergence was found among NSDUH 12th-graders and other grades, for any past month marijuana use, and when controlling demographic characteristics.Conclusions: An increase in adolescent marijuana use has not accompanied recent rapid decreases in marijuana risk perceptions. Policy makers may consider broader prevention strategies in addition to targeting marijuana risk perceptions. Further monitoring of predictors of marijuana use trends is needed as states legalize recreational marijuana use. [ABSTRACT FROM AUTHOR]

Background: How adolescent substance use and perceived availability of substances have changed during the COVID-19 pandemic remain largely unknown. Substantial reduction in availability of substances would present a unique opportunity to consider the supply-side hypothesis that reductions in drug availability will lead to reductions in drug prevalence.Methods: Longitudinal data come from Monitoring the Future and are based on responses from 582 adolescents who were originally surveyed as part of a national sample of 12th grade students in early 2020, one month before social distancing policies began. They were surveyed again after social distancing policies were implemented, in the summer of 2020.Results: Perceived availability of marijuana and alcohol declined across the two survey waves at the largest levels ever recorded in the 46 years of the project, by an absolute 17 %, p < .01 and 24 %, p < .01, respectively. Despite these declines, prevalence levels did not significantly change across the two waves for marijuana use in the past 30 days or for binge drinking in the past two weeks. Perceived availability of vaping devices significantly declined, from 73 % to 63 %, as did nicotine vaping prevalence in the past 30 days, from 24 % to 17 %.Conclusions: Perceived availability of marijuana, alcohol, and vaping devices declined at historic rates during the pandemic of 2020. Lack of accompanying reductions in prevalence for marijuana and binge drinking demonstrates the substantial challenges facing a supply-side approach to the reduction of adolescent use of these substances. [ABSTRACT FROM AUTHOR]

Abstract: Background: This study uses large nationally representative samples of White, Black, Mexican American, Puerto Rican, Other Latina, Asian American, and American Indian 8th-grade girls to examine racial/ethnic differences and similarities in patterns, trends, and socioeconomic correlates of cigarette use. Methods: The data are drawn from the University of Michigan''s Monitoring the Future study. Prevalence and trend data (from 1991 to 2007) in girls’ cigarette use were examined by racial/ethnic subgroup. Logistic regression analyses were conducted to determine the extent to which socioeconomic factors predict girls’ cigarette use, and whether the relationships between socioeconomic status (SES) and smoking differed across racial/ethnic subgroup. Results: Cigarette use was highest among American Indian girls; at an intermediate level among Mexican American, Puerto Rican, Other Latinas, and White girls; and lowest among Black and Asian American girls. Trend data show that cigarette use has declined for all racial/ethnic subgroups, and that small but consistent racial/ethnic differences in girls’ cigarette use have persisted. Generally, girls who did not live in two-parent households, whose parents had lower levels of educational attainment, who attended lower SES schools, and who had more disposable income were more likely than their peers to smoke. That said, however, the relationships between smoking and parental education and school SES were, on average, stronger for White girls than for Black or Hispanic (Mexican American, Other Latina, Puerto Rican) girls. Conclusions: Future research should seek to understand the mechanisms by which low SES impacts smoking. [Copyright &y& Elsevier]

Background: This study uses large nationally representative samples of White, Black, Mexican American, Puerto Rican, Other Latina, Asian American, and American Indian 8th-grade girls to examine racial/ethnic differences and similarities in patterns, trends, and socioeconomic correlates of cigarette use.Methods: The data are drawn from the University of Michigan's Monitoring the Future study. Prevalence and trend data (from 1991 to 2007) in girls' cigarette use were examined by racial/ethnic subgroup. Logistic regression analyses were conducted to determine the extent to which socioeconomic factors predict girls' cigarette use, and whether the relationships between socioeconomic status (SES) and smoking differed across racial/ethnic subgroup.Results: Cigarette use was highest among American Indian girls; at an intermediate level among Mexican American, Puerto Rican, Other Latinas, and White girls; and lowest among Black and Asian American girls. Trend data show that cigarette use has declined for all racial/ethnic subgroups, and that small but consistent racial/ethnic differences in girls' cigarette use have persisted. Generally, girls who did not live in two-parent households, whose parents had lower levels of educational attainment, who attended lower SES schools, and who had more disposable income were more likely than their peers to smoke. That said, however, the relationships between smoking and parental education and school SES were, on average, stronger for White girls than for Black or Hispanic (Mexican American, Other Latina, Puerto Rican) girls.Conclusions: Future research should seek to understand the mechanisms by which low SES impacts smoking. [ABSTRACT FROM AUTHOR]