Adult Marijuana Use Research Articles

Novel approaches for teen alcohol, young adult marijuana use

Alcoholism & Drug Abuse WeeklyVolume 29, Issue 45 p. 5-6 Articles Novel approaches for teen alcohol, young adult marijuana use Alison Knopf, Alison KnopfSearch for more papers by this author Alison Knopf, Alison KnopfSearch for more papers by this author First published: 19 November 2017 https://doi.org/10.1002/adaw.31782Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume29, Issue4520 November 2017Pages 5-6 RelatedInformation

Loose regulation of medical marijuana programs associated with higher rates of adult marijuana use but not cannabis use disorder.

Most US states have passed medical marijuana laws (MMLs), with great variation in program regulation impacting enrollment rates. We aimed to compare changes in rates of marijuana use, heavy use and cannabis use disorder across age groups while accounting for whether states enacted medicalized (highly regulated) or non-medical mml programs. Difference-in-differences estimates with time-varying state-level MML coded by program type (medicalized versus non-medical). Multi-level linear regression models adjusted for state-level random effects and covariates as well as historical trends in use. Nation-wide cross-sectional survey data from the US National Survey of Drug Use and Health (NSDUH) restricted use data portal aggregated at the state level. Participants comprised 2004-13 NSDUH respondents (n~67 500/year); age groups 12-17, 18-25 and 26+ years. States had implemented eight medicalized and 15 non-medical MML programs. Primary outcome measures included (1) active (past-month) marijuana use; (2) heavy use (>300days/year); and (3) cannabis use disorder diagnosis, based on DSM-IV criteria. Covariates included program type, age group and state-level characteristics throughout the study period. Adults 26+ years of age living in states with non-medical MML programs increased past-month marijuana use 1.46% (from 4.13 to 6.59%, P=0.01), skewing towards greater heavy marijuana by 2.36% (from 14.94 to 17.30, P=0.09) after MMLs were enacted. However, no associated increase in the prevalence of cannabis use disorder was found during the study period. Our findings do not show increases in prevalence of marijuana use among adults in states with medicalized MML programs. Additionally, there were no increases in adolescent or young adult marijuana outcomes following MML passage, irrespective of program type. Non-medical marijuana laws enacted in US states are associated with increased marijuana use, but only among adults aged 26+ years. Researchers and policymakers should consider program regulation and subgroup characteristics (i.e. demographics) when assessing for population level outcomes. Researchers and policymakers should consider program regulation and subgroup characteristics (i.e. demographics) when assessing for population level outcomes.

Predictors of Adult Marijuana Use Among Parents and Nonparents.

The current study examined predictors of marijuana use among adults, including subsamples of adults who are actively parenting (i.e., have regular face-to-face contact with a child) and those who have no children. Participants were a community sample of 808 adults and two subsamples drawn from the full group: 383 adults who were actively parenting and 135 who had no children. Multilevel models examined predictors of marijuana use in these three groups from ages 27 to 39. Becoming a parent was associated with a decrease in marijuana use. Regular marijuana use in young adulthood (ages 21-24), partner marijuana use, and pro-marijuana attitudes increased the likelihood of past-year marijuana use among all participants. Being a primary caregiver (among parents) was associated with less marijuana use. Overall, predictors of marijuana use were similar for all adults, regardless of parenting status. Study results suggest that the onset of parenthood alone may be insufficient to reduce adult marijuana use. Instead, preventive intervention targets may include changing adult pro-marijuana attitudes and addressing marijuana use behaviors of live-in partners. Lastly, universal approaches targeting parents and nonparents may be effective for general adult samples.

Relationship Between Frequent Recreational Cannabis (Marijuana and Hashish) Use and Periodontitis in Adults in the United States: National Health and Nutrition Examination Survey 2011 to 2012.

Recreational use of cannabis, following its legalization in some countries, poses emergent oral and periodontal health concerns. The objective of this study is to examine the relationship between frequent recreational cannabis (FRC) (marijuana and hashish) use and periodontitis prevalence among adults in the United States. Data from the National Health and Nutrition Examination Survey (NHANES) 2011 to 2012 were analyzed. Primary outcome (periodontitis) was defined using the Centers for Disease Control and Prevention/American Academy of Periodontology classification as well as continuous measurements of probing depth (PD) and clinical attachment loss (AL). Exposure of interest was self-reported cannabis use, defined as "FRC use" versus "non-FRC use." Bivariate and multivariable regression models were performed using the entire analytical sample (model 1) as well as those who had never used tobacco (never-users) (model 2). Of 1,938 participants with available cannabis use data and essential covariates, 26.8% were FRC users. Mean number of sites per participant with PD ≥4, ≥6, and ≥8 mm and AL ≥3, ≥5, and ≥8 mm was significantly higher among FRC users than among non-FRC users (mean difference in number of PD sites: 6.9, 5.6, and 5.6; P <0.05; mean difference in number of AL sites: 12.7, 7.6, and 5.6; P <0.05). Average AL was higher among FRC users than among non-FRC users (1.8 versus 1.6 mm; P = 0.004). Bivariate analysis revealed positive (harmful) association between FRC use and severe periodontitis in the entire sample (odds ratio [OR]: 1.7, 95% confidence interval [CI]: 1.3 to 2.4; P = 0.002) as well as in never-smokers (OR: 2.0, 95% CI: 1.2 to 3.5; P = 0.01). This association was retained in multivariable models adjusted for demographics (age, sex, race/ethnicity, and income level), alcohol and tobacco use, diabetes mellitus, and past periodontal treatment (model 1: adjusted OR [aOR]: 1.4, 95% CI: 1.1 to 1.9; P = 0.07; model 2: aOR: 1.9, 95% CI: 1.1 to 3.2; P = 0.03). FRC use is associated with deeper PDs, more clinical AL, and higher odds of having severe periodontitis.

Prevalence and Patterns of Marijuana Use in Young Adults With Inflammatory Bowel Disease.

Recent studies in adults report symptom relief with marijuana use in patients with inflammatory bowel disease (IBD). We assessed the prevalence, pattern, effects, and adverse effects of marijuana use in young adults with IBD. We conducted a prospective questionnaire survey study at a pediatric IBD clinic. All patients (18-21 years of age) answered anonymous questionnaires about demographics, IBD, medications, and marijuana use. Fifty-three patients (mean age 18.7 years, 32 boys) were enrolled. Thirty-seven patients (70%) reported using marijuana currently or in the past. There was no statistically significant difference between the users and nonusers of marijuana regarding demographics, disease activity, or medications. Despite prolonged use of marijuana, 70% of patients did not discuss it with their gastroenterologists. Twenty-four patients used marijuana medicinally for IBD symptoms in addition to medical therapy. Although majority found marijuana to be moderately/very helpful, complete relief of symptoms such as abdominal pain, poor appetite, nausea, and diarrhea was seen in 29%, 37%, 14%, and 10% of patients, respectively. Only half of patients reported knowledge of possible adverse effects of marijuana and 19% of patients reported mild neuropsychiatric adverse effects. Overall, 98% of patients supported legalization of marijuana and 85% were interested in using medical marijuana if it became legally available. We found a high rate of marijuana use in our cohort of young adults with IBD. Majority of users report symptom improvement but do not inform physicians. Future well-controlled studies are necessary to assess role of marijuana in IBD therapy.

Marijuana use in adults with sickle cell disease

Marijuana use in adults with sickle cell disease

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

Perceived safety and controllability of events: Markers of risk for marijuana use in young adults?

Drawing on constructs from the trauma literature, the current study evaluated perceptions of safety and controllability of events as potential markers of risk for marijuana use. In addition, we characterized these perceptions in relation to individual level substance abuse risk factors (marijuana expectancies, impulsivity, depression, and anxiety), gender, and race. Data were collected via web survey from college students at two northeastern universities (n=228, 82.0% female). Controllability of events (CE) was rated significantly higher by Blacks than Whites. Safety/vulnerability (SV) and CE were associated with impulsivity, depression, and anxiety. CE was also associated with marijuana expectancies. Logistic regression analyses revealed a modest but significant association between SV and lifetime use even after adjusting for race, gender, age, and individual level substance abuse risk factors (odds ratio=1.10, 95% confidence intervals:1.02–1.18). No association between SV and past 3month frequency of use or between CE and either marijuana outcome was found. Findings support a link between perceptions of safety and ever using marijuana. They further demonstrate overlap of both perceived safety and controllability of events with substance use related risk factors, and suggest that they differ by race. Additional studies that assess substance use more broadly and query trauma history, using larger, more diverse samples, are needed to more fully grasp the relevance of these constructs to substance use, including their potential as targets for substance abuse prevention efforts.

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.

The Impact of Marijuana Legalization on Adolescent Use, Consequences, and Perceived Risk

ABSTRACTBackground: Currently, only four states have legalized recreational marijuana use for adults over 21 years of age. Therefore, little is known about the influence that legalization will have on adolescent marijuana use. Objectives: This study examines how marijuana legalization has impacted the frequency and consequences of adolescent use in a sample of participants in a school-based, substance use intervention. We hypothesized that adolescents enrolled in the intervention in years after marijuana legalization would present with more problematic use compared to those enrolled prior, and that changes in the perceived risk of marijuana would be a mechanism of problematic use. Methods: Participants were 262 students enrolled in a school-based substance use intervention in 2010 to 2015. The Customary Drinking and Drug Use Record, Alcohol and Drug Use Consequences Questionnaire, and a decisional balance matrix were used to assess marijuana frequency, negative consequences, and perceived risk of use. A mediation model was used to test the degree to which marijuana legalization may lead to increased frequency and consequences of use through perceived risk. Results: Findings indicated a significantly positive correlation between marijuana-related consequences and perceived risk post legalization. Despite relatively equal use between both groups, adolescents in the legalization group experienced higher levels of perceived risk and increased negative consequences. Conclusions/Importance: Due to the rising legalization status of marijuana in the United States, it is imperative that psychoeducation is provided to adults and adolescents about the consequences of underage marijuana use.

Marijuana use and use disorders in adults in the USA, 2002–14: analysis of annual cross-sectional surveys

The study of marijuana use disorders is urgently needed because of increasing marijuana legalisation in multiple jurisdictions, the effect of marijuana use on future risk of psychiatric disorders, and deleterious effects of marijuana exposure. Thus, understanding trends of marijuana use and use disorders and examining factors that might drive these trends (eg, perceptions of harms from marijuana use) is essential. We analysed data from US civilians aged 18 years or older who participated in annual, cross-sectional US National Surveys on Drug Use and Health from 2002 to 2014. The sample in each US state was designed to be approximately equally distributed between participants aged 12-17 years, 18-25 years, and 26 years or older. For each survey year, we estimated prevalence of marijuana use and use disorders, initiation of marijuana use, daily or near daily use, perception of great or no risk of harm from smoking marijuana, perception of state legalisation of medical marijuana use, and mean number of days of marijuana use in the previous year. Descriptive analyses, multivariable logistic regressions, and zero-truncated negative binomial regressions were applied. 596 500 adults participated in the 2002-14 surveys. Marijuana use increased from 10·4% (95% CI 9·97-10·82) to 13·3% (12·84-13·70) in adults in the USA from 2002 to 2014 (β=0·0252, p<0·0001), and the prevalence of perceiving great risk of harm from smoking marijuana once or twice a week decreased from 50·4% (49·60-51·25) to 33·3% (32·64-33·96; β=-0·0625, p<0·0001). Changes in marijuana use and risk perception generally began in 2006-07. After adjusting for all covariates, changes in risk perceptions were associated with changes in prevalence of marijuana use, as seen in the lower prevalence of marijuana use each year during 2006-14 than in 2002 when perceiving risk of harm from smoking marijuana was included in models. However, marijuana use disorders in adults remained stable at about 1·5% between 2002 and 2014 (β=-0·0042, p=0·22). Prevalence and frequency of marijuana use increased in adults in the USA starting in approximately 2007 and showing significantly higher results in multivariable models during 2011-14 (compared with 2002). The associations between increases in marijuana use and decreases in perceiving great risk of harm from smoking marijuana suggest the need for education regarding the risk of smoking marijuana and prevention messages. None.

Marijuana use in adults admitted to a Canadian epilepsy monitoring unit.

Epidemiologic evidence supporting antiseizure properties of cannabis is limited and controversial. We determined the prevalence of marijuana use and its perceived effects in patients with and without epilepsy. Information was collected over 14months from consecutive adult patients admitted to an epilepsy monitoring unit using a 27-item anonymous questionnaire. Patients with cognitive impairment unable to understand the questions or give informed consent and readmissions were not recruited. Subjects were divided into 4 groups, those with epileptic seizures, those with psychogenic nonepileptic seizures (PNES), those with both epileptic and PNES, and those with other nonepileptic events. Patients with exclusively epileptic seizures were compared with those with exclusively PNES. From 310 patients, 18 undiagnosed cases were excluded leaving a cohort of 292 patients with median age 35 (range: 27-49) years; 57.2% female. Epilepsy was documented in 190 (65.1%), PNES in 64 (21.9%), and both types of seizures in 26 (8.9%). Median duration of seizure disorder was longer (2 [1-9] vs. 13 [5.7-25] years; p<0.001) and seizure frequency lower (daily or weekly in 62.3% vs. 44.9%; p=0.03) in patients with epilepsy compared with those in patients with PNES. Overall, 166 (57%) had tried marijuana, and 36.2% used it over the past year. Utilization was 57.1% in sole epilepsy and 64.1% in sole PNES, but daily use was more likely in epilepsy (59% vs. 33.3%). Estimated mean dose was 1g/day. Marijuana use was associated with tobacco smoking (p<0.001) but not alcohol use. Eight patients used other street drugs. Improvement in seizures was perceived by 84% in those with epilepsy and 72.7% in those with PNES. In the 2 groups, stress was decreased in 84.9% and 88%, sleep improved in 77.3% and 88%, and memory/concentration was better in 32% and 28%, respectively. Antiepileptic drug side effects were decreased in 53.2% of marijuana users. Perceived effect on epileptic seizures correlated with effect on stress (r=0.35, p=0.004). Adverse effects of marijuana were mild and reported in 30.7% but included possible seizure precipitation in 5 patients with epilepsy. Patients with uncontrolled epilepsy or nonepileptic events had a high rate of marijuana use with associated perceived improvements in seizure control, stress, sleep, and drug side effects. Stress reduction may contribute to the perceived impact of marijuana on seizures and nonepileptic events in 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.

Prevalence of marijuana and other substance use before and after Washington State's change from legal medical marijuana to legal medical and nonmedical marijuana: Cohort comparisons in a sample of adolescents

ABSTRACTBackground: A growing number of states have new legislation extending prior legalization of medical marijuana by allowing nonmedical marijuana use for adults. The potential influence of this change in legislation on adolescent marijuana and other substance use (e.g., spillover or substitution effects) is uncertain. We capitalize on an ongoing study to explore the prevalence of marijuana and other substance use in 2 cohorts of adolescents who experienced the nonmedical marijuana law change in Washington State at different ages. Methods: Participants were 8th graders enrolled in targeted Tacoma, Washington public schools and recruited in 2 consecutive annual cohorts. The analysis sample was 238 students who completed a baseline survey in the 8th grade and a follow-up survey after the 9th grade. Between the 2 assessments, the second cohort experienced the Washington State nonmedical marijuana law change, whereas the first cohort did not. Self-report survey data on lifetime and past-month marijuana, cigarette, and alcohol use were collected. Results: Multivariate multilevel modeling showed that cohort differences in the likelihood of marijuana use were significantly different from those for cigarette and alcohol use at follow-up (adjusting for baseline substance initiation). Marijuana use was higher for the second cohort than the first cohort, but this difference was not statistically significant. Rates of cigarette and alcohol use were slightly lower in the second cohort than in the first cohort. Conclusions: This exploratory study found that marijuana use was more prevalent among teens shortly after the transition from medical marijuana legalization only to medical and nonmedical marijuana legalization, although the difference between cohorts was not statistically significant. The findings also provided some evidence of substitution effects. The analytic technique used here may be useful for examining potential long-term effects of nonmedical marijuana laws on adolescent marijuana use and substitution or spillover effects in future studies.

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.

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