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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.
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Conducta del Adolescente , COVID-19 , Fumar Marihuana , Uso de la Marihuana , Trastornos Relacionados con Sustancias , Adolescente , Consumo de Bebidas Alcohólicas/epidemiología , Estudios Transversales , Humanos , Fumar Marihuana/epidemiología , Uso de la Marihuana/epidemiología , Pandemias , Estudiantes , Trastornos Relacionados con Sustancias/epidemiologíaRESUMEN
Given the promise of the web push plus e-mail survey design for providing cost-effective and high-quality data (Patrick et al. 2018, 2019) as an alternative to a paper-and-pencil mailed survey design for the longitudinal Monitoring the Future (MTF) study, the current study sought to further enhance the web push condition. The MTF sample is based on US nationally representative samples of 12th grade students surveyed annually. The MTF control group for the current study included participants who completed the in-school baseline survey in the 12th grade and were selected to participate in their first follow-up survey in 2017 via mailed surveys (N = 1,222). A supplementary sample (N = â¼2,450) was assigned to one of the two sequential mixed-mode conditions. Those in condition 1 (N = 1,198), or mail push, were invited to complete mailed surveys and later given a web survey option. Those in condition 2 (N = 1,173), or enhanced web push, were invited to complete a web survey (the same as in the 2014 study, but with the addition of text messages and quick response (QR) codes and the web survey was optimized for mobile devices) and then later given a mailed survey option. Research aims were to examine response rates across conditions, as well as how responses were distributed across mode (paper, web), devices (computer, smartphone, table), and method of accessing the web survey (hand-entered URL, QR code, e-mail link, SMS link). Response rates differed significantly: the MTF control group was 34.2 percent, mail push was 35.4 percent, and enhanced web push was 42.05 percent. The higher response rate in the enhanced web push condition suggests that the additional strategies were effective at bringing in more respondents. Key estimates produced by the enhanced web push condition did not differ from those of the MTF control group.
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PURPOSE: This study estimated self-reported perceived negative marijuana use consequences among a national sample of U.S. young adults, examining consequence prevalence differences by use frequency, college attendance, living situation, employment, sex, and race/ethnicity; and use frequency/sociodemographic characteristic interactions. METHODS: A subsample of 1,212 respondents from the 2004-2018 class cohorts of 12th grade students participating in the nationally-representative Monitoring the Future study was surveyed up to two times from modal ages 19 through 22 (in 2008-2019). Respondents self-reported negative consequences related to their own past 12-month marijuana use. Bivariate and multivariable models examined subgroup differences in consequence prevalence. RESULTS: Approximately 60% of those using frequently (20+ use occasions in the past 30 days) and 35% of those using non-frequently reported negative consequences. Among all young adult marijuana users, 31.1% reported emotional/physical consequences, 12.9% performance/financial consequences, and 12.3% relational consequences. Use frequency was positively associated with consequence likelihood, excluding regret and unsafe driving. Among college students, frequent use was more strongly associated with any and performance/financial consequences. Controlling for use frequency, men reported more performance/financial consequences; relational consequences were higher among Hispanic (vs. White) respondents, and those living with parents, employed full-time, and not attending 4-year colleges. CONCLUSION: Young adults using marijuana reported a wide range of negative use consequences; likelihood of most consequences increased with higher use frequency. Perceived consequences varied by college attendance, living situation, employment, sex, and race/ethnicity. Efforts to reduce negative marijuana consequences may be strengthened by recognizing and addressing the different types of negative consequences users perceive.
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Fumar Marihuana , Uso de la Marihuana , Trastornos Relacionados con Sustancias , Adulto , Humanos , Masculino , Fumar Marihuana/epidemiología , Uso de la Marihuana/epidemiología , Autoinforme , Estudiantes , Adulto JovenRESUMEN
OBJECTIVE: This study examined past-2-week driving after marijuana use (DMU) and driving after having five or more drinks (D5D) during young adulthood, specifically focusing on associations between within-person change in social roles (living situation, marriage, parenthood, education, employment) and mediators (perceived risk, evenings out, and religiosity) from modal ages 19 to 30. METHOD: Multilevel analyses were conducted using survey data collected from 2013 to 2019 from 1,873 adults (1,060 women; total number of data collection waves = 7,037) participating in the longitudinal Monitoring the Future study. RESULTS: Change across waves from not being married to married was associated with lower DMU likelihood at any particular wave both directly and via mediation through wave-level change in evenings out. Change in employment (not employed to employed full time) was associated with higher D5D likelihood at any particular wave both directly and via mediation through change in evenings out. Wave-level change in other social roles was indirectly associated with DMU/D5D likelihood via wave-level change in evenings out. CONCLUSIONS: Change in all social roles examined was associated with change in evenings out, which appears to be a primary, proximal predictor of young adult DMU/D5D. Improved understanding of how socialization change is associated with driving after substance use may strengthen efforts to reduce the harms associated with such driving behaviors.
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Conducción de Automóvil , Cannabis , Fumar Marihuana , Uso de la Marihuana , Adulto , Consumo de Bebidas Alcohólicas , Humanos , Uso de la Marihuana/epidemiología , Encuestas y Cuestionarios , Adulto JovenRESUMEN
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.
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COVID-19 , Preparaciones Farmacéuticas , Trastornos Relacionados con Sustancias , Vapeo , Adolescente , Humanos , Pandemias , Distanciamiento Físico , Políticas , Prevalencia , SARS-CoV-2 , Trastornos Relacionados con Sustancias/epidemiologíaRESUMEN
OBJECTIVE: This study examined age-related change in alcohol use, marijuana use, and the association between the two, from ages 18 to 55, in a national longitudinal sample. METHOD: Data were from national Monitoring the Future study participants (N = 11,888) who were high school seniors in 1976-1980 and were eligible to respond to the age 55 survey in 2013-2017. Time-varying effect modeling was used to model past-30-day prevalence and associations between alcohol and marijuana across ages 18-55, overall and by sex, race/ethnicity, and college attendance. RESULTS: Marijuana prevalence peaked at age 18 and was lowest in the late 40s; alcohol prevalence peaked at age 22 and was lowest in the early 40s. Associations between alcohol and marijuana use were strongest at age 18. Significant differences were observed by sex, race/ethnicity, and college attendance (e.g., women's use was lower and decreased faster in the late 30s than men's; White respondents' alcohol and marijuana use were higher and peaked before Black respondents'; compared with non-attenders, college attenders' use was higher for alcohol but lower for marijuana). The alcohol and marijuana use association was strongest at ages 18-20 for most subgroups, except Black respondents, for whom the association was strongest at age 30. CONCLUSIONS: Longitudinal data showed patterns of alcohol and marijuana use across adulthood. Such patterns highlight sociodemographic risk factors across the life span, ages that should be targeted for clinician awareness and intervention efforts, and populations at particular risk of harm from alcohol and marijuana co-use during adulthood.
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Consumo de Bebidas Alcohólicas/epidemiología , Uso de la Marihuana/epidemiología , Adolescente , Adulto , Negro o Afroamericano/estadística & datos numéricos , Etnicidad/estadística & datos numéricos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Factores de Riesgo , Universidades , Población Blanca/estadística & datos numéricos , Adulto JovenRESUMEN
Importance: US adolescent nicotine vaping increased at a record pace from 2017 to 2019, prompting new national policies to reduce access to flavors of vaping products preferred by youth. Objective: To estimate prevalence, perceived harm, and accessibility of nicotine vaping products among US adolescents from 2017 to 2020. Design, Setting, and Participants: This survey study includes data from Monitoring the Future, which conducted annual, cross-sectional, school-based, nationally representative surveys from 2017 to 2020 of 10th- and 12th-grade students (results pooled grades, n = 94â¯320) about vaping and other topics. Main Outcomes and Measures: Prevalence of self-reported nicotine vaping; vaping brand and flavor used most often; perceived risk of nicotine vaping; and perceived ease of getting vaping devices, nicotine solutions for vaping, and flavored solutions. Results: In 2020, Monitoring the Future surveyed 8660 students in 10th and 12th grade, of whom 50.6% (95% CI, 47%-54%) were female, 13% (95% CI, 8%-21%) were non-Hispanic Black, 29% (95% CI, 21%-40%) were Hispanic, and 53% (95% CI, 42%-63%) were non-Hispanic White. Nicotine vaping prevalence in 2020 was 22% (95% CI, 19%-25%) for past 30-day use, 32% (95% CI, 28%-37%) for past 12-month use, and 41% (95% CI, 37%-46%) for lifetime use; these levels did not significantly change from 2019. Daily nicotine vaping (use on ≥20 days of the last 30 days) significantly declined from 9% (95% CI, 8%-10%) to 7% (95% CI, 6%-9%) over 2019 to 2020. JUUL brand prevalence in the past 30 days decreased from 20% (95% CI, 18%-22%) in 2019 to 13% (95% CI, 11%-15%) in 2020, while use of other brands increased. Among youth who vaped in the past 30 days in 2020, the most often used flavor was fruit at 59% (95% CI, 55%-63%), followed by mint at 27% (95% CI, 24%-30%) and menthol at 7% (95% CI, 5%-9%); significantly fewer reported easy access to vaping devices and nicotine solutions compared with 2019; and 80% (95% CI, 75%-84%) reported they could easily get a vaping flavor other than tobacco or menthol. Among all youth, perceived risk of both occasional and regular nicotine vaping increased from 2019 to 2020. Conclusions and Relevance: Increasing US adolescent nicotine vaping trends from 2017 to 2019 halted in 2020, including a decline in daily vaping. Decreases in perceived accessibility of some vaping products, as well as increases in perceived risk of nicotine vaping, occurred from 2019 to 2020. Yet, adolescent nicotine vaping remains highly prevalent, flavors remain highly accessible, and declines in JUUL use were countered by increased use of other brands.
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Conducta del Adolescente/psicología , Actitud Frente a la Salud , Conducta Peligrosa , Vapeo/epidemiología , Vapeo/psicología , Adolescente , Estudios Transversales , Femenino , Humanos , Modelos Logísticos , Masculino , Prevalencia , Riesgo , Autoinforme , Estados Unidos/epidemiología , Vapeo/efectos adversosAsunto(s)
Conducta del Adolescente/psicología , Consumo de Bebidas Alcohólicas/epidemiología , Uso de la Marihuana/epidemiología , Adolescente , Consumo de Bebidas Alcohólicas/psicología , Estudios Transversales , Femenino , Humanos , Masculino , Uso de la Marihuana/psicología , Prevalencia , Autoinforme , Factores Sexuales , Estados Unidos/epidemiologíaRESUMEN
OBJECTIVE: This study estimated the percentage of age 35 and 55 adults reporting using medical marijuana intended for someone else (diverted use) and compared demographics and health status of such users with respondents reporting recommended use (i.e., individuals with a medical marijuana recommendation for their own health conditions) and to respondents using marijuana not intended for medical use (nonmedical marijuana [NMM] use). METHOD: Cross-sectional analyses were conducted using complex sample survey data collected from 2013 to 2018 from 12,138 adults (6,998 women) at modal ages 35 or 55 participating in the U.S. national Monitoring the Future study. RESULTS: Diverted use was reported by 72.9% [95% CI, 66.4, 79.4] and 64.3% [56.0, 72.7] of age 35 and 55 past-12-month medical marijuana users, respectively. Age 35 diverted users were more likely than recommended users to not work full time and have no postsecondary education. Age 55 recommended users were more likely than NMM users to be retired. Age 35 diverted users were less likely than recommended users to report poor physical health (odds ratio [OR] = 0.40 [0.17, 0.94]). Age 55 diverted users were less likely than recommended users to report three or more poor health conditions (OR = 0.22 [0.09, 0.55]) and any qualifying conditions (OR = 0.21 [0.08, 0.58]). Prevalence of these conditions was similar between diverted and NMM users. CONCLUSIONS: Results indicated a substantial degree of nonmedical (i.e., recreational) marijuana use. Diverted and NMM users reported generally similar levels of health conditions, whereas diverted users had fewer indicators of poor health than recommended users.
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Abuso de Marihuana/epidemiología , Uso de la Marihuana/epidemiología , Marihuana Medicinal/administración & dosificación , Adulto , Estudios Transversales , Femenino , Estado de Salud , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Encuestas y Cuestionarios , Estados UnidosRESUMEN
This study (a) examined changes in marijuana and cigarette initiation sequencing and (b) considered implications of such changes for prevention efforts by examining associations between initiation sequencing and current adolescent substance use. Analyses used 2000-2019 cross-sectional data from the national Monitoring the Future (MTF) study (78,252 U.S. 12th grade students). Models examined trends in six distinct patterns of initiation order, and multivariable associations between order of initiation and 30-day cigarette and marijuana use prevalence, cigarette and marijuana use frequency among users, and nicotine and marijuana vaping prevalence. While the percentage of students initiating neither cigarettes nor marijuana increased, increases also were observed in marijuana-only initiation (the fastest-growing pattern) and initiation of marijuana before cigarettes; these increases were accompanied by a significant decrease in cigarette-only initiation. Cigarette use prevalence and frequency were highest among students initiating cigarettes before marijuana; marijuana use prevalence and frequency were highest among students initiating marijuana before cigarettes. Cigarette and marijuana prevalence, as well as marijuana frequency, were lowest among students initiating only a single substance. Nicotine vaping was less prevalent among students initiating a single substance versus both substances, but no significant differences were observed in nicotine vaping prevalence between those initiating only cigarettes versus only marijuana. Implications of these findings for prevention efforts are discussed in the frameworks of both the common liability model and route of administration model.
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Fumar Marihuana/epidemiología , Fumar Marihuana/tendencias , Fumar/epidemiología , Fumar/tendencias , Vapeo/epidemiología , Vapeo/tendencias , Adolescente , Estudios Transversales , Humanos , Prevalencia , Encuestas y Cuestionarios , Estados Unidos/epidemiologíaRESUMEN
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.
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Conducta del Adolescente/psicología , Bases de Datos Factuales/tendencias , Uso de la Marihuana/epidemiología , Uso de la Marihuana/psicología , Estudiantes/psicología , Adolescente , Estudios Transversales , Femenino , Humanos , Masculino , Uso de la Marihuana/tendencias , Autoinforme , Estados Unidos/epidemiologíaRESUMEN
OBJECTIVE: Adolescent cigarette smoking declined steadily and substantially from 2000 to 2018. This paper considers the potential consequences of this 'great decline' for the prevalence of other drug use among adolescents. METHODS: Data are annual, cross-sectional, nationally representative Monitoring the Future surveys of more than 1.2 million US students in 12th, 10th and 8th grades from 2000 to 2018. Analyses include trends in the past 12 months' non-medical amphetamine, tranquillisers and opioid use overall, among ever and never cigarette smokers, and projected if adolescent cigarette smoking levels had remained at 2000 levels. RESULTS: Within groups of ever and never cigarette smokers, the prevalence for each of the three substances has either changed little or overall increased in 2018 as compared with 2000. When the two groups were combined into one pool, the overall prevalence for each of the drugs declined by about half. The decline resulted from the growing group of never smokers, whose levels of non-medical drug use over the study period were at least four times lower than the levels of ever smokers. CONCLUSIONS: The results support the 'gateway' prediction that declines in cigarette smoking among adolescents pull downward their non-medical use of amphetamines, tranquillisers and opioids. Continuing to reduce adolescent smoking through policy and programmatic prevention efforts should have further positive spillover effects on adolescent drug use.
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Fumar Cigarrillos , Sistemas Electrónicos de Liberación de Nicotina , Preparaciones Farmacéuticas , Adolescente , Estudios Transversales , Humanos , Prevalencia , Fumar/epidemiología , Estudiantes , Encuestas y CuestionariosRESUMEN
This study examines the two-year follow up (data collected in 2016 at modal age 21/22) of an original mixed-mode longitudinal survey experiment (data collected at modal age 19/20 in 2014). The study compares participant retention in the experimental conditions to retention in the standard Monitoring the Future (MTF) control condition (participants who completed an in-school baseline survey in 12th grade in 2012 or 2013 and were selected to participate in the first follow-up survey by mail in 2014, N=2,451). A supplementary sample who completed the 12th grade baseline survey in 2012 or 2013 but were not selected to participate in the main MTF follow-up (N=4,950) were recruited and randomly assigned to one of three experimental conditions: 1: Mail Push, 2: Web Push, 3: Web Push + Email in 2014 and again in 2016. Results from the first experiment indicated that Condition 3 (Web Push + Email) was promising based on similar response rates and lower costs (Patrick et al. 2018). The current study examines how experimental condition and type of 2014 response were associated with response in 2016, the extent to which response mode and device type changed from 2014 to 2016, and cumulative cost comparisons across conditions. Results indicated that responding via web in 2014 was associated with greater odds of participation again in 2016 regardless of condition; respondents tended to respond in the same mode although the "push" condition did move respondents toward web over paper; device type varied between waves; and the cumulative cost savings of Web Push + Email grew larger compared to the MTF Control. The web push strategy is therefore promising for maintaining respondent engagement while reducing cost.
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INTRODUCTION: This study presents the first nationally-representative estimates of adolescent nicotine prevalence that take into account adolescent reports of substances vaped. These reports allow nicotine estimates that consider the impact of the newly-emerged group of adolescents who report vaping only non-nicotine substances such as flavoring and/or marijuana and do not use nicotine in any form - a group typically treated as nicotine users. METHODS: Data come from Monitoring the Future and are a randomly-selected subsample of 2231 U.S. 12th grade students who answered surveys with detailed questions on tobacco use and vaping in 2017. RESULTS: Among 12th grade students 24.7% used nicotine in the last 30â¯days. This estimate does not include the 3.8% of students who vaped only non-nicotine substances and did not use nicotine in any other form. These students more closely resemble their peers who do not use nicotine than those who do, in terms of perceived risk and disapproval of cigarettes, as well as percentage of friends who use cigarettes. CONCLUSIONS: A decline in nicotine prevalence was statistically significant, but not strikingly large, after taking into account students who vape non-nicotine substances and do not use nicotine in any form. These students are largely similar to their peers who do not use nicotine, which underscores the importance of efforts to alert youth that they may be vaping nicotine unknowingly, and prevent them from doing so.
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BACKGROUND: Mental health problems and mental health related mortality have increased among adolescents, particularly girls. These trends have implications for etiology and prevention and suggest new and emerging risk factors in need of attention. The present study estimated age, period, and cohort effects in depressive symptoms among US nationally representative samples of school attending adolescents from 1991 to 2018. METHODS: Data are drawn from 1991 to 2018 Monitoring the Future yearly cross-sectional surveys of 8th, 10th, and 12th grade students (N = 1,260,159). Depressive symptoms measured with four questions that had consistent wording and data collection procedures across all 28 years. Age-period-cohort effects estimated using the hierarchical age-period-cohort models. RESULTS: Among girls, depressive symptoms decreased from 1991 to 2011, then reversed course, peaking in 2018; these increases reflected primarily period effects, which compared to the mean of all periods showed a gradual increase starting in 2012 and peaked in 2018 (estimate = 1.15, p < 0.01). Cohort effects were minimal, indicating that increases are observed across all age groups. Among boys, trends were similar although the extent of the increase is less marked compared to girls; there was a declining cohort effect among recently born cohorts, suggesting that increases in depressive symptoms among boys are slower for younger boys compared to older boys in recent years. Trends were generally similar by race/ethnicity and parental education, with a positive cohort effect for Hispanic girls born 1999-2004. CONCLUSIONS: Depressive symptoms are increasing among teens, especially among girls, consistent with increases in depression and suicide. Population variation in psychiatric disorder symptoms highlight the importance of current environmental determinants of psychiatric disorder risk, and provide evidence of emerging risk factors that may be shaping a new and concerning trend in adolescent mental health.
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Depresión/epidemiología , Salud Mental/tendencias , Estudiantes/psicología , Adolescente , Estudios Transversales , Depresión/etnología , Etnicidad/psicología , Femenino , Hispánicos o Latinos/psicología , Humanos , Masculino , Factores de Riesgo , Suicidio/tendencias , Estados Unidos/epidemiologíaRESUMEN
BACKGROUND AND AIMS: Long-term frequent marijuana use is associated with significant negative outcomes, yet little is known about the longitudinal course of marijuana use among those who start frequent use during adolescence. Objectives are (a) to identify latent patterns of within-person marijuana use from ages 19-30 years among 12th graders reporting frequent marijuana use, (b) to examine if membership in identified patterns has changed across historical time and (c) to examine if key covariates differentiate class membership. DESIGN, SETTING, PARTICIPANTS: Longitudinal, national US panel data from 4423 individuals [53.4% of the eligible sample; 2744 (62%) males] who reported frequent marijuana use in 12th grade (modal age 18 years; senior year cohorts 1976-2006) followed biennially from ages 19/20 to 29/30. MEASUREMENTS: Self-reported past 30-day marijuana use (frequent use defined as use on 20+ occasions), demographics, college graduation, marriage and parenthood. FINDINGS: Repeated-measures latent class analysis (RMLCA) identified five latent classes of past 30-day marijuana use from ages 19/20 to 29/30: continued frequent users (estimated membership 23.4%); frequent to non-frequent users (15.5%); consistent non-frequent users (18.4%); non-frequent users to discontinuers (19.5%); and discontinuers (23.2%). In multivariable models, membership in the highest-risk latent class (continued frequent users) versus one or more of the lower-risk latent classes was more likely for recent cohorts (P = 0.038 to <0.001), as well as those who did not marry (P = 0.039 to < 0.001) or become parents (P = 0.001) by modal age 29/30. CONCLUSIONS: Nearly one in four 12th grade (modal age 18 years) frequent marijuana users in the US continues to report high frequency use to age 30; the proportion continuing high frequency use across young adulthood has increased among more recent cohorts.