Adult Marijuana Research Articles

Altered resting state fMRI response in young adult marijuana users and heavy drinkers

Altered resting state fMRI response in young adult marijuana users and heavy drinkers

Contextual Effects of Neighborhoods and Schools on Adolescent and Young Adult Marijuana Use in the United States.

Little is known about the unique contribution of schools vs neighborhoods in driving adolescent marijuana use. This study examined the relative contribution of each setting and the influence of school and neighborhood socioeconomic status on use. We performed a series of cross-classified multilevel logistic models predicting past 30-day adolescent (N = 18 329) and young adult (N = 13 908) marijuana use using data from Add Health. Marijuana use differed by age, sex, race/ethnicity, and public assistance in adjusted models. Variance parameters indicated a high degree of clustering by school (σ2 = 0.30) and less pronounced clustering by neighborhood (σ2 = 0.06) in adolescence when accounting for both levels simultaneously in a cross-classified multilevel model. Clustering by school persisted into young adulthood (σ2 = 0.08). Parental receipt of public assistance increased the likelihood of use during adolescence (odds ratio = 1.39; 95% confidence interval: 1.19–1.59), and higher parental education was associated with increased likelihood of use in young adulthood. These findings indicate that both contexts may be promising locations for intervention.

Time-varying effect modeling to address new questions in behavioral research: Examples in marijuana use.

Time-varying effect modeling (TVEM), a statistical approach that enables researchers to estimate dynamic associations between variables across time, holds enormous potential to advance behavioral research. TVEM can address innovative questions about processes that unfold across different levels of time. We present a conceptual introduction to the approach and demonstrate 4 innovative ways to approach time in TVEM to advance research on the etiology of marijuana use. First, we examine changes in associations across historical time to understand how the link between marijuana use attitudes and marijuana use behavior has shifted from 1976 to present; gender differences in the relevance of attitudes diminished over time and were no longer significant after 2004. Second, we examine age-varying associations between heavy episodic drinking and marijuana use across developmental time and demonstrate that this dynamic association is substantially stronger during ages 14 to 16 compared with later ages. Third, we explore the complex association between age of onset of marijuana use and adult marijuana use to identify precise age ranges during which the onset of use is most risky, and demonstrate how this complex association is more salient for males. Finally, we examine changes in marijuana use as a function of time relative to the birth of first child and show how this transition is more crucial for females. All empirical examples in this methodological demonstration rely on existing data from cross-sectional or panel studies. We conclude with thoughts on future directions for the application and further development of TVEM in behavioral research. (PsycINFO Database Record

The effects of perceived quality on behavioral economic demand for marijuana: A web-based experiment

BackgroundGiven the growing legalization of recreational marijuana use and related increase in its prevalence in the United States, it is important to understand marijuana's appeal. We used a behavioral economic (BE) approach to examine whether the reinforcing properties of marijuana, including “demand” for marijuana, varied as a function of its perceived quality. MethodsUsing an innovative, Web-based marijuana purchase task (MPT), a sample of 683 young-adult recreational marijuana users made hypothetical purchases of marijuana across three qualities (low, mid and high grade) at nine escalating prices per joint, ranging from $0/free to $20. ResultsWe used nonlinear mixed effects modeling to conduct demand curve analyses, which produced separate demand indices (e.g., Pmax, elasticity) for each grade of marijuana. Consistent with previous research, as the price of marijuana increased, marijuana users reduced their purchasing. Demand also was sensitive to quality, with users willing to pay more for higher quality/grade marijuana. In regression analyses, demand indices accounted for significant variance in typical marijuana use. ConclusionsThis study illustrates the value of applying BE theory to young adult marijuana use. It extends past research by examining how perceived quality affects demand for marijuana and provides support for the validity of a Web-based MPT to examine the appeal of marijuana. Our results have implications for policies to regulate marijuana use, including taxation based on the quality of different marijuana products.

Parent and peer pathways linking childhood experiences of abuse with marijuana use in adolescence and adulthood

IntroductionThe social developmental processes by which child maltreatment increases risk for marijuana use are understudied. This study examined hypothesized parent and peer pathways linking preschool abuse and sexual abuse with adolescent and adult marijuana use. MethodsAnalyses used data from the Lehigh Longitudinal Study. Measures included child abuse (physical abuse, emotional abuse, domestic violence, and neglect) in preschool, sexual abuse up to age 18, adolescent (average age=18years) parental attachment and peer marijuana approval/use, as well as adolescent and adult (average age=36years) marijuana use. ResultsConfirming elevated risk due to child maltreatment, path analysis showed that sexual abuse was positively related to adolescent marijuana use, whereas preschool abuse was positively related to adult marijuana use. In support of mediation, it was found that both forms of maltreatment were negatively related to parental attachment, which was negatively related, in turn, to having peers who use and approve of marijuana use. Peer marijuana approval/use was a strong positive predictor of adolescent marijuana use, which was a strong positive predictor, in turn, of adult marijuana use. ConclusionsResults support social developmental theories that hypothesize a sequence of events leading from child maltreatment experiences to lower levels of parental attachment and, in turn, higher levels of involvement with pro-marijuana peers and, ultimately, to both adolescent and adult marijuana use. This sequence of events suggests developmentally-timed intervention activities designed to prevent maltreatment as well as the initiation and progression of marijuana use among vulnerable individuals.

Marijuana Use Is Associated with Behavioral Approach and Depressive Symptoms in Adolescents and Emerging Adults.

BackgroundRepeated CB1 binding due to THC results in downregulation of the endocannabinoid system in cortex and limbic regions, perhaps disrupting frontolimbic functioning. This is particularly a concern in young adults who are still undergoing neurodevelopment in frontal and limbic regions. Such disruptions may be linked to increased depressive symptoms, anxiety symptoms, and executive dysfunction, and decreased behavioral approach.ObjectivesHere we examine the influence of young adult marijuana use on anxiety, depressive symptoms, behavioral approach, and executive dysfunction. The influence of alcohol and gender were also assessed.Methods84 participants (42 MJ, 42 controls) aged 18–25 were balanced for gender (39 F). Exclusion criteria included: MRI contraindications, left handed, comorbid Axis-I disorders, major medical or neurologic disorders, prenatal issues, or prenatal alcohol/illicit drug exposure, or excessive other drug use. Participants completed the FrsBE, BIS/BAS, State-Trait Anxiety Inventory (State), and BDI-II. Multiple regressions were run to predict anxiety, depressive symptoms, behavioral approach, and executive dysfunction from MJ group status, past year alcohol use, gender, and MJ*gender interactions, controlling for cotinine and ecstasy.ResultsMJ group predicted increased depressive symptoms (p =.049). Decreased fun-seeking (p =.04), reward response (p =.01), and BAS total (p =.01) were predicted by MJ group. Gender predicted decreased reward responsiveness in females (p =.049) and decreased BIS in females (p =.03). Female marijuana users had increased anxiety symptoms (p =.04) and increased disinhibition (p =.04). Increased cotinine predicted increased drive (p =.046), reward responsiveness (p =.008) and BAS Total (p =.02). Apathy and Executive Dysfunction were not predicted by any measures. All results had small effect sizes.Conclusions/ImportanceDepressive symptoms were greater in MJ users, while behavioral approach was decreased. Cotinine levels predicted increased behavioral approach. Female MJ users also had greater anxiety and disinhibition. In sum, these findings suggest sub-clinical threshold deficits related to regular marijuana use that are indicative of a need to prevent marijuana use in adolescents and young adults.

Marijuana Legalization and Parents' Attitudes, Use, and Parenting in Washington State

PurposeThe recent legalization of nonmedical marijuana use in several U.S. states has unknown implications for those who are actively parenting. This study examined parents' reactions to marijuana legalization and changes in attitudes and behaviors over time. MethodsData were from a gender-balanced, ethnically diverse sample of 395 parents in Washington State who were participating in the longitudinal Seattle Social Development Project. Participants were interviewed 15 times between 1985 (age 10) and 2014 (age 39). Adult nonmedical marijuana use was legalized in Washington in 2012 and retail outlets opened in 2014. ResultsResults showed (1) one third of parents incorrectly believed the legal age of nonmedical marijuana use to be 18; (2) significant increase in approval of adult marijuana use and decrease in perceived harm of regular use; (3) wide opposition to teen use and use around one's children; and (4) substantial increases in frequency of use and marijuana use disorder among parents who used. ConclusionsDespite increased acceptance and frequency of adult use, parents remain widely opposed to teen use but need facts and strategies for talking with their children about marijuana.

Mostly Smokers: Identifying Subtypes of Emerging Adult Substance Users

ABSTRACTBackground: The concurrent use of marijuana and other substances among emerging adults (ages 18–25) is a major public health problem. This study examined if there are distinct subtypes of emerging adult marijuana users and if these are associated with demographic and substance use variables. Methods: The design was a cross-sectional interview with a community sample of 1,503 emerging adults in the northeastern U.S. who reported last month marijuana use. We used latent class analysis (LCA) to identify distinct subtypes of emerging adults who used additional substances and examined predictors of the latent classes. Results: We identified three distinct classes of emerging adults who use substances: “mostly smokers” (those who primarily use marijuana and nicotine), “moderate users” (those who primarily use marijuana and/or heavy episodic alcohol), and “polysubstance users.” Polysubstance users had higher probabilities of use of all assessed substances (e.g. cocaine, opiates, sleep medications, stimulants, synthetic marijuana, and inhalants) than the other two groups. Not being currently enrolled in school and male gender were associated with mostly smokers and polysubstance users group status. Conclusions: We identified a distinct group of emerging adult marijuana users who primarily smoke marijuana and cigarettes, suggesting that there could be a shared vulnerability for risk of co-occurrence.

Examination of the Divergence in Trends for Adolescent Marijuana Use and Marijuana-Specific Risk Factors in Washington State

PurposeAs marijuana laws have become more permissive, survey data on adolescents in the United States have shown an increase in marijuana-specific risk factors, particularly in the proportion of youth who do not perceive marijuana use as harmful. Prevalence of marijuana use among youth, however, has changed little. Using representative data from Washington State, which has legalized medical and nonmedical marijuana for adults, we examined two competing hypotheses to account for this divergence in population trends. MethodsData were from 2000 to 2014 biennial Washington State surveys of 10th-grade students. First, we assessed whether associations between marijuana use and marijuana-specific risk factors have weakened over time. Second, we examined whether decreases in alcohol and cigarette use can account for the lack of expected increase in marijuana use prevalence. ResultsDespite stability in marijuana use prevalence, there were increases in marijuana-specific risk factors of low perceived harm, youth favorable attitudes about use, and perceived community attitudes favorable to use. Associations between marijuana use and marijuana use predictors varied little across time; if anything, the positive association between low perceived harm and marijuana use grew stronger. Decreases in prevalence of alcohol and cigarette use largely accounted for stability in marijuana use during a period when marijuana risk factors increased. ConclusionsDecreases in other types of substance use or in the underlying, common risk for substance use may have mitigated effects of increases in marijuana-specific risk factors.

Normalising desistance: contextualising marijuana and cocaine use careers in young adults.

Although there is a vast literature on drug use and addiction, there is little work that addresses the long-term use of drugs within the general population. We take a more contextual look in examining longitudinal drug use patterns over the course of 14years for a representative sample of young adults in their late teens and early twenties in the United States using the National Longitudinal Survey of Youth (NLSY). We use a growth trajectory modelling approach for cocaine and marijuana users to determine general use careers. Using contextual and life-course variables, we then estimate a multinomial logistic regression model to predict group membership. In addition to establishing general use career groups, we ask how well mainstream theories comport with our findings and how the different chemical makeup of cocaine and marijuana influence our findings. We find four general use career groups: (i) high use/late desistance; (ii) peaked use/strong desistance; (iii) low use; and (iv) stable use/gradual desistance. Our results suggest similar careers for users of both drugs, with desistance over time as the rule for all groups. We also find some support for life-course and contextual factors in drug using patterns, but our findings challenge other psychological and criminological theories.

Research round-up

Research round-up

Altered Neural Processing to Social Exclusion in Young Adult Marijuana Users

BackgroundPrevious studies have reported that peer groups are one of the most important predictors of adolescent and young adult marijuana use, and yet the neural correlates of social processing in marijuana users have not been studied. MethodsIn the current study, marijuana-using young adults (n = 20) and nonusing control subjects (n = 22) participated in a neuroimaging social exclusion task called Cyberball, a computerized ball-tossing game in which the participant is excluded from the game after a predetermined number of ball tosses. ResultsControl subjects, but not marijuana users, demonstrated significant activation in the insula, a region associated with negative emotion, when being excluded from the game. Both groups demonstrated activation of the ventral anterior cingulate cortex, a region associated with affective monitoring, during peer exclusion. Only the marijuana group showed a correlation between ventral anterior cingulate cortex activation and scores on a self-report measure of peer conformity. ConclusionsThis study indicates that marijuana users show atypical neural processing of social exclusion. This differential activation may have preexisted and may have contributed to the onset of marijuana use, and/or it may have developed as a result of marijuana exposure.

Metabolic Syndrome Among Marijuana Users in the United States: An Analysis of National Health and Nutrition Examination Survey Data

BackgroundResearch on the health effects of marijuana use in light of its increased medical use and the current obesity epidemic is needed. Our objective was to explore the relationship between marijuana use and metabolic syndrome across stages of adulthood. MethodsAn analysis of 20- to 59-year-olds (n = 8478) who completed the 2005-2010 National Health and Nutrition Examination Surveys was conducted. Marijuana use was categorized as: never used, past use (used previously but not within the last 30 days), and current use (≥1 day in the last 30 days). Metabolic syndrome was defined as ≥3 of the following: elevated fasting glucose, high triglycerides, low high-density-lipoprotein cholesterol, elevated systolic/diastolic blood pressure, and increased waist circumference. An age-stratified analysis was conducted to examine the relationship between marijuana use and metabolic syndrome among emerging adults (20-30 years), adults (31-44 years), and middle-aged adults (45-59 years). ResultsFourteen percent (13.8%) of current marijuana users and 17.5% of past marijuana users presented with metabolic syndrome, compared with 19.5% of never users (P = .0003 and P = .03, respectively). Current marijuana users had lower odds of presenting with metabolic syndrome than never users (adjusted odds ratio [AOR] 0.69; 95% confidence interval [CI], 0.47-1.00; P = .05). Among emerging adults, current marijuana users were 54% less likely than never users to present with metabolic syndrome. Current (AOR 0.49; 95% CI, 0.25-0.97) and past (AOR 0.61; 95% CI, 0.40-0.91) middle-aged adult marijuana users were less likely to have metabolic syndrome than never users. ConclusionsCurrent marijuana use is associated with lower odds of metabolic syndrome across emerging and middle-aged US adults. Future studies should examine the biological pathways of this relationship.

Up in Smoke: Neighborhood Contexts of Marijuana Use from Adolescence Through Young Adulthood.

The current understanding of the neighborhood contexts wherein adolescent substance use emerges remains limited by conflicting findings regarding geographic variation in, and neighborhood effects on, both the prevalence of and risk factors for such use. Using four waves of longitudinal data from the National Longitudinal Study of Adolescent to Adult Health [n = 18,697 (51% female, 54% White, 24% Black, 16 % Hispanic, 7% Asian, 2% American Indian/Other)], latent class analysis, and growth curve modeling, this study identified distinct neighborhood types--patterned by race/ethnicity, socioeconomic class, and geography--and explored how trajectories of adolescent and young adult marijuana use differed across neighborhood types. The results demonstrated complexity in neighborhood contexts, illustrating variation in trajectories of marijuana use across neighborhood types heretofore unobserved in neighborhoods research, and largely unexplained by key individual, family, and peer risk and protective factors. This approach highlights how social structural forces intersect and anchor trajectories of youth substance-using risk behavior

Contextual risks linking parents’ adolescent marijuana use to offspring onset

ObjectiveWe studied the extent to which parent marijuana use in adolescence is associated with marijuana use onset in offspring through contextual family and peer risks. MethodFathers assessed (n=93) since childhood, their 146 offspring (n=83 girls), and offspring's mothers (n=85) participated in a longitudinal study. Using discrete-time survival analysis, fathers’ (prospectively measured) and mothers’ (retrospective) adolescent marijuana use was used to predict offspring marijuana use onset through age 19 years. Parental monitoring, child exposure to marijuana use, peer deviance, peer marijuana use, and perceptions of parent disapproval of child use were measured before or concurrent with onset. ResultsParents’ adolescent marijuana use was significantly associated with less monitoring, offspring alcohol use, the peer behaviors, exposure to adult marijuana use, and perceptions of less parent disapproval. Male gender and the two peer behaviors were positively associated with children's marijuana use onset, controlling for their alcohol use. Parents’ adolescent marijuana use had a significant indirect effect on child onset through children's deviant peer affiliations and a composite contextual risk score. ConclusionsParents’ histories of marijuana use may contribute indirectly to children's marijuana use onset through their influence on the social environments children encounter; specifically, those characterized by more liberal use norms, exposure to marijuana use and deviant and marijuana-using peers, and less adult supervision. Given that alcohol use onset was controlled, findings suggest that the contextual factors identified here confer unique risk for child marijuana use onset.

Assessing the overlap between tobacco and marijuana: Trends in patterns of co-use of tobacco and marijuana in adults from 2003–2012

BackgroundAs marijuana legalization and acceptability increase in the U.S., it is important to understand the potential impact on tobacco use. Accordingly, we assessed prevalence, correlates, and ten-year trends in co-use of marijuana and tobacco among U.S. adults. MethodsData came from 378,459 adults participating in the 2003–2012 National Survey on Drug Use and Health, an annual, cross-sectional, household survey. Data from 2011–2012 were used to compute the most recent prevalence of past 30-day marijuana and tobacco use (co-use). Data from 2003–2012 were used to compute demographic correlates of co-use, overall trends in co-use, and trends by age, race, and sex. We also assessed trends in tobacco use among marijuana users and marijuana use among tobacco users. ResultsFrom 2011 to 2012, 5.2% of participants were past month co-marijuana and tobacco users, 24.0% were tobacco-only users, and 2.3% were marijuana-only users. From 2003 to 2012, prevalence of co-use increased overall (p<.0001), and among males and females (p<.001, p<.05), those ages 26–34 (p<.001) and 50+years (p<.0001), and Whites (p<.01), Blacks (p<.05), and Hispanics (p<.01); there were no changes among adults 18–25years. Tobacco use among marijuana users decreased between 2003 and 2012 (from 74.3% to 69.6%, p<.0001), while marijuana use increased among tobacco users (from 14.2% to 17.8, p<.0001). ConclusionsCo-use of tobacco and marijuana increased from 2003–2012, with marijuana use increasing among past-month tobacco users and tobacco use declining among past-month marijuana users. Improved surveillance of co-use is needed as marijuana legalization policies expand and become more integrated in communities.

Prefrontal and parietal volumes and cognition in emerging adult marijuana users

Prefrontal and parietal volumes and cognition in emerging adult marijuana users

Longitudinal family effects on substance use among an at-risk adolescent sample

ObjectiveAdult and peer factors may influence whether adolescents use alcohol and other drugs (AOD). This longitudinal study examined the direct effects of adult monitoring, perceived adult AOD use, and cultural values on adolescent AOD use. MethodsParticipants were 193 at-risk adolescents referred to a California diversion program called Teen Court for a first-time AOD offense. We assessed youth reports of past 30day AOD use (any alcohol use, heavy drinking, marijuana use), demographics, changes in parental monitoring and family values (from baseline to follow-up 180days later), as well as family structure and perceived adult substance use at follow-up. ResultsAdolescents who reported that a significant adult in their life used marijuana were more likely to have increased days of drinking, heavy drinking, and marijuana use at follow-up. Higher levels of familism (importance the teen places on their family's needs over their own needs) and being in a nuclear family served as protective factors for future alcohol use. Additionally, poor family management was associated with increased alcohol use and heavy drinking. ConclusionFindings highlight how family management and perceptions of adult marijuana use influence subsequent adolescent AOD use, and how an increase in familism over time is associated with a decrease in adolescent drinking. Tailoring interventions, by including the teen's family and/or providing support to adults who use AOD may be crucial for improving interventions for adolescent AOD use.

Neighborhood environment and marijuana use in urban young adults.

Risk factors for marijuana use in older adolescents and young adults have focused primarily on family environment and peer affiliation. A growing body of work has examined the relationship between environmental context and young adult substance use. This study builds on previous research linking neighborhood environment to young adult marijuana use by exploring two distinct features of neighborhoods, namely the physical (e.g., broken windows) and social environment (e.g., adults watching youth). Data were obtained from a longitudinal sample of 398 predominately African American young adults living in an urban environment. The data also included observational measures of physical and social order and disorder collected on the young adult's residential block. Exploratory structural equation modeling (ESEM) was utilized to test hypothesized relationships between these two features of the neighborhood environment and past year young adult marijuana use. A two-factor model of neighborhood environment with good fit indices was selected (CFI = 0.97, RMSEA = 0.037). There was a positive and significant direct effect from neighborhood physical disorder to marijuana use (0.219, p < 0.05) controlling for gender, race, and free and reduced price meal (FARPM) status. The direct effect from neighborhood social environment to marijuana use was not significant. These results converge with previous research linking vacant housing with young adult marijuana use but do not provide empirical support for the neighborhood social environment as a determinant of drug taking. Better explication of the social environment is needed to understand its relationship to drug use.

Getting Higher: Co-Occurring Drug Use Among Marijuana-Using Emerging Adults

The most widely used illicit drug in the United States continues to be marijuana, and its use among emerging adults continues to increase. Marijuana use can result in a range of negative consequences and has been associated with other drug use in adolescents and emerging adults. This study examined the relationship between marijuana use frequency and the use of six other drug classes (opiates, cocaine, stimulants, hallucinogens, inhalants, and sleep medications) among emerging adults. A cross-sectional interview design was used with a community sample of 1,075 emerging adults in the northeastern United States. Using logistic regression analysis controlling for age, ethnicity, gender, and frequency of binge alcohol, daily marijuana use was found to be associated with a significant increase in the expected odds of opiate, cocaine, stimulant, hallucinogen, inhalant, and tobacco use. The findings identify a subgroup of emerging adult marijuana users—those who use daily—that may be vulnerable to additional negative consequences associated with polysubstance use.