Adolescent Marijuana Use Research Articles

Preliminary findings demonstrating latent effects of early adolescent marijuana use onset on cortical architecture

BackgroundAs the most commonly used illicit substance during early adolescence, long-term or latent effects of early adolescent marijuana use across adolescent developmental processes remain to be determined. MethodsWe examined cortical thickness, gray/white matter border contrast (GWR) and local gyrification index (LGI) in 42 marijuana (MJ) users. Voxelwise regressions assessed early-onset (age <16) vs. late-onset (≥16 years-old) differences and relationships to continued use while controlling for current age and alcohol use. ResultsAlthough groups did not differ by onset status, groups diverged in their correlations between cannabis use and cortical architecture. Among early-onset users, continued years of MJ use and current MJ consumption were associated with thicker cortex, increased GWR and decreased LGI. Late-onset users exhibited the opposite pattern. This divergence was observed in all three morphological measures in the anterior dorsolateral frontal cortex (p<.05, FWE-corrected). ConclusionsDivergent patterns between current MJ use and elements of cortical architecture were associated with early MJ use onset. Considering brain development in early adolescence, findings are consistent with disruptions in pruning. However, divergence with continued use for many years thereafter suggests altered trajectories of brain maturation during late adolescence and beyond.

Testing gene × environment moderation of tobacco and marijuana use trajectories in adolescence and young adulthood.

This study examines the main and interaction effects of known social risk factors for substance use (inadequate parental monitoring and substance using friends) in adolescence and a polygenic score in predicting marijuana and tobacco use in adolescence and young adulthood. Phenotypic and genetic data were derived from a longitudinal study of a cohort of urban, predominately African American youth. Last year substance-use measures were collected annually from 8th grade through age 22. Participant self-reports of substance-using friends and parent monitoring were obtained yearly from Grades 8 to 12. Using longitudinal latent class analysis, the authors identified parallel developmental trajectories of tobacco and marijuana use and parent monitoring and the proportion of substance-using friends. Two trajectories were identified for tobacco and marijuana use, characterized by moderate versus little-to-no use. Additionally, 2 latent profiles were found for the social environment profiles: those characterized by higher parent monitoring and a lower proportion of substance-using friends versus lower parent monitoring and a higher proportion of substance-using friends. We found main and interaction effects for the polygenic score and social environment profile in predicting the longitudinal classes of marijuana and tobacco use. With respect to the interaction effect, membership in the moderate-use classes of marijuana and tobacco use was highest among those in the social environment profile characterized by lower parent monitoring and a higher proportion of substance-using friends.

Marijuana use by youth, schizophrenia genetic risk examined

Following three independent population‐based samples of adolescents, an international team of researchers has observed a link between marijuana use and brain development in male adolescents with a genetic risk for developing schizophrenia, according to a new study. For the study, researchers set out to evaluate whether the association between cannabis use and cortical maturation in adolescents is moderated by a polygenic risk score — the combined effect of selected risk alleles — for schizophrenia.

Brain activation to negative stimuli mediates a relationship between adolescent marijuana use and later emotional functioning

This work investigated the impact of heavy marijuana use during adolescence on emotional functioning, as well as the brain functional mediators of this effect. Participants (n=40) were recruited from the Michigan Longitudinal Study (MLS). Data on marijuana use were collected prospectively beginning in childhood as part of the MLS. Participants were classified as heavy marijuana users (n=20) or controls with minimal marijuana use. Two facets of emotional functioning—negative emotionality and resiliency (a self-regulatory mechanism)—were assessed as part of the MLS at three time points: mean age 13.4, mean age 19.6, and mean age 23.1. Functional neuroimaging data during an emotion-arousal word task were collected at mean age 20.2. Negative emotionality decreased and resiliency increased across the three time points in controls but not heavy marijuana users. Compared with controls, heavy marijuana users had less activation to negative words in temporal, prefrontal, and occipital cortices, insula, and amygdala. Activation of dorsolateral prefrontal cortex to negative words mediated an association between marijuana group and later negative emotionality. Activation of the cuneus/lingual gyrus mediated an association between marijuana group and later resiliency. Results support growing evidence that heavy marijuana use during adolescence affects later emotional outcomes.

Past 15-year trends in adolescent marijuana use: Differences by race/ethnicity and sex

BackgroundThe potential for increases in adolescent marijuana use is an important concern given recent changes in marijuana policy. The purpose of this study was to estimate trends in marijuana use from 1999 to 2013 among a national sample of US high school students. We examine changes over time by race/ethnicity and sex. MethodsData are from the National Youth Risk Behavior Survey (YRBS), which involves biennial, school-based surveys that generate nationally representative data about 9th–12th grade students in the United States. Students self-reported sex, race/ethnicity, and marijuana use (i.e., lifetime use, past 30-day use, any use before age 13). We generated national estimates of the prevalence of marijuana use for the time period, and also tested for linear and quadratic trends (n=115,379). ResultsThe prevalence of lifetime marijuana use decreased modestly from 1999 to 2009 (44% to 37%), and has increased slightly since 2009 (41%). Other marijuana use variables (e.g., past 30-day use) followed a similar pattern over time. The prevalence of past 30-day use from 1999 to 2013 for all groups and both sexes was 22.5%, and it was lowest among Asians and highest among American Indian/Alaska Natives. Although boys have historically had a higher prevalence of marijuana use, results indicate that male–female differences in marijuana use decreased over time. ConclusionDespite considerable changes in state marijuana policies over the past 15 years, marijuana use among high school students has largely declined. Continued surveillance is needed to assess the impact of policy changes on adolescent marijuana use.

Chronic adolescent marijuana use as a risk factor for physical and mental health problems in young adult men.

Some evidence suggests that youth who use marijuana heavily during adolescence may be particularly prone to health problems in later adulthood (e.g., respiratory illnesses, psychotic symptoms). However, relatively few longitudinal studies have prospectively examined the long-term physical and mental health consequences associated with chronic adolescent marijuana use. The present study used data from a longitudinal sample of Black and White young men to determine whether different developmental patterns of marijuana use, assessed annually from early adolescence to the mid-20s, were associated with adverse physical (e.g., asthma, high blood pressure) and mental (e.g., psychosis, anxiety disorders) health outcomes in the mid-30s. Analyses also examined whether chronic marijuana use was more strongly associated with later health problems in Black men relative to White men. Findings from latent class growth curve analysis identified 4 distinct subgroups of marijuana users: early onset chronic users, late increasing users, adolescence-limited users, and low/nonusers. Results indicated that the 4 marijuana use trajectory groups were not significantly different in terms of their physical and mental health problems assessed in the mid-30s. The associations between marijuana group membership and later health problems did not vary significantly by race. Findings are discussed in the context of a larger body of work investigating the potential long-term health consequences of early onset chronic marijuana use, as well as the complications inherent in studying the possible link between marijuana use and health effects.

Parental involvement in brief interventions for adolescent marijuana use.

Adolescents (aged 12-18 years) identified in a school setting as abusing marijuana and other drugs were randomly assigned to complete 1 of 2 brief interventions (BIs). Adolescents and their parent (N = 259) were randomly assigned to receive either a 2-session adolescent only (BI-A) or a 2-session adolescent and additional parent session (BI-AP). Interventions were manualized and delivered in a school setting by trained counselors. Adolescents were assessed at intake and at 6 months following the completion of the intervention. Using a latent construct representing 6-month marijuana use outcomes, current findings supported previous research that BI-AP resulted in superior outcomes when compared to BI-A. The presence of a marijuana dependence diagnosis at baseline predicted poorer outcomes when compared to youth without a diagnosis. Both baseline diagnostic status and co-occurring conduct problems interacted with intervention condition in predicting marijuana use outcomes. A marijuana dependence diagnosis resulted in poorer marijuana use outcomes within the BI-A condition when compared to BI-AP. Co-occurring conduct problems were associated with poorer marijuana use outcomes within the BI-AP intervention when compared to BI-A. Implications for implementing BIs given diagnostic status, parent involvement, and co-occurring conduct problems are discussed.

Insomnia complaints and substance use in German adolescents: did we underestimate the role of coffee consumption? Results of the KiGGS study.

The purpose of the study was to study the associations of tobacco, alcohol, marijuana, and coffee use and insomnia complaints (IC) in adolescents with special consideration of the influence of coffee consumption on these relationships. 7698 Subjects aged 11-17years were investigated in a cross-sectional study within the German Health Interview and Examination Survey for Children and Adolescents. Self-report questionnaires were distributed to the participants. Hierarchical regression analyses were performed to assess possible effects of coffee consumption on the association of tobacco, alcohol, and marijuana use with IC. Common risk factors for insomnia were included in the adjusted analyses. Tobacco, alcohol, marijuana and coffee use displayed significant bivariate associations with IC. After adjusting the first three substances for coffee consumption, their associations with IC were reduced considerably. After additionally adjusting for other potential confounders (age, gender, socio-economic status, externalizing and internalizing psychiatric problems, media use, bodyweight, medical condition), frequent coffee consumption, high alcohol intake and frequent smoking contributed to the prediction of IC in male subjects while frequent coffee consumption and high alcohol intake predicted the occurrence of IC in females. Coffee consumption could be an important risk factor for IC in adolescents and it significantly affects the association of smoking, alcohol, and marijuana with IC. Future research that includes long-term studies about psychoactive substance use (PSU) and sleep should also consider coffee consumption. Parents, educators, clinicians, and researchers should be aware of the potentially hazardous influence of PSU, especially coffee, alcohol and tobacco, on sleep in young individuals.

Predicting Young Adult Degree Attainment by Late Adolescent Marijuana Use

PurposeThe purpose of this study was to assess whether infrequent and frequent marijuana use at age 19/20 years predicts receipt of educational degrees by the mid-20s, independent of confounding age 18 adolescent risk factors. MethodsData were from the Monitoring the Future study, an annual nationally representative survey of high school seniors followed into adulthood. Thirteen cohorts (1990–2002) of high school seniors were followed longitudinally to their mid-20s (n = 4,925; 54% female). We used logistic regression and propensity score matching with successive inclusion of age 18 risk factors and substance use to compare age 19/20 frequent marijuana users (six or more occasions in past 30 days) to nonusers, frequent users to infrequent users (1–6 occasions), and infrequent users to nonusers on their likelihood of degree attainment by the mid-20s. ResultsFrequent marijuana users were less likely than infrequent users and nonusers to earn bachelor's degrees, even after controlling for a host of age 18 risk factors (e.g., family socioeconomic background, academic performance, educational expectations, truancy). However, these differences were reduced in magnitude to statistical nonsignificance when we controlled for age 18 substance use. Across analyses, the proportion reaching this educational milestone did not differ significantly between infrequent users and nonusers. ConclusionsResults support a growing body of work suggesting that frequent marijuana use predicts a lower likelihood of postsecondary educational attainment, and this difference may originate during secondary school.

Strain and sex differences in puberty onset and the effects of THC administration on weight gain and brain volumes

The use of recreational marijuana is widespread and frequently begins and persists through adolescence. Some research has shown negative consequences of adolescent marijuana use, but this is not seen across studies, and certain factors, like genetic background and sex, may influence the results. It is critical to identify which characteristics predispose an individual to be susceptible to the negative consequences of chronic exposure to marijuana in adolescence on brain health and behavior. To this end, using males and females of two strains of rats, Long–Evans hooded (LER) and Wistar (WR) rats, we explored whether these anatomically and behaviorally dimorphic strains demonstrated differences in puberty onset and strain-specific effects of adolescent exposure to Δ9-tetrahydrocannabinol (THC), the main psychoactive component of marijuana. Daily 5mg/kg treatment began on the day of puberty onset and continued for 14days. Of particular interest were metrics of growth and volumetric estimates of brain areas involved in cognition that contain high densities of cannabinoid receptors, including the hippocampus and its subregions, the amygdala, and the frontal cortex. Brain volumetrics were analyzed immediately following the treatment period. LER and WR females started puberty at different ages, but no strain differences were observed in brain volumes. THC decreased weight gain throughout the treatment period for all groups. Only the hippocampus and some of its subregions were affected by THC, and increased volumes with THC administration was observed exclusively in females, regardless of strain. Long-term treatment of THC did not affect all individuals equally, and females displayed evidence of increased sensitivity to the effects of THC, and by extension, marijuana. Identifying differences in adolescent physiology of WR and LER rats could help determine the cause for strain and sex differences in brain and behavior of adults and help to refine the use of animal models in marijuana research.

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.

The role of neighborhood in urban black adolescent marijuana use

BackgroundThe present study examined the influence of neighborhood factors on transitions in marijuana involvement during adolescence in a sample of primarily low-income, urban Black youth. Methods556 Black adolescents were interviewed annually beginning in first grade as part of a longitudinal study. Latent class analysis (LCA) was used to examine stages of marijuana involvement from 6th to 9th grades. The influence of neighborhood disorder, drug activity, violent crime, safety and disadvantage on transitions in marijuana involvement was tested using latent transition analysis (LTA). ResultsThere was evidence for three stages of involvement: no involvement, offered, and use and problems. Involvement increased steadily during adolescence with a slightly greater risk to transition from offers to use between 6th and 7th grades. Neighborhood disorder (AOR=1.04, CI=1.00, 1.08), drug activity (AOR=1.12, CI=1.02, 1.22) and disadvantage (AOR=1.44, CI=1.10, 1.92) were associated with the transition from marijuana offers to use and problems. Neighborhood disorder (AOR=1.07, CI=1.02, 1.11), drug activity (AOR=1.19, CI=1.10, 1.29) and violent crime (AOR=1.17, CI=1.03, 1.32) were associated with transitioning rapidly from no involvement to use and problems. ConclusionsUnderstanding how neighborhoods could be organized and provided with supports to discourage marijuana use and promote non-drug using behaviors should be an important goal of any prevention program in low-income, urban Black neighborhoods. Enhancing citizen participation and mobilization to address the social processes of neighborhood disorder has the potential to reduce marijuana involvement in these neighborhoods.

Stress and Alcohol, Cigarette, and Marijuana Use Among Latino Adolescents in Families with Undocumented Immigrants.

Families in which one or more members are undocumented immigrants experience unique hardships. Yet, little is known about stress and substance use among adolescents growing up in these families. The present study examined associations between two sources of adolescent stress (i.e., low parental involvement due to contextual constraints and family economic insecurity) and lifetime alcohol, cigarette, and marijuana use among adolescents in families with undocumented members. The sample was comprised of 102 adolescents (10-18 years old) and one of his or her parents. Participants responded a survey in English or Spanish. Adolescent lifetime use of alcohol, cigarette, and marijuana was 51%, 32.4%, and 37.3%, respectively. Chi-Square analyses found no significant gender differences in lifetime substance use. Logistic regression models showed that adolescent stress due to hindered parental involvement increased the odds of both lifetime cigarette and marijuana use after controlling for gender, age, linguistic acculturation, familism, parental control, and negative peer affiliation. Being a girl increased the odds of lifetime alcohol use. Family economic stress was not associated with lifetime substance use. Results suggest that hindered parental involvement might be a stressor and a risk factor for cigarette and marijuana use among adolescents growing up in families with undocumented members. Because parents in these families are likely to be undocumented, policies that allow immigrants to apply for legal status could improve parents' working conditions and facilitate parental involvement; in turn, such policies could decrease the risk for adolescent substance use among children of Latino immigrants.

Neuroimaging of the dopamine/reward system in adolescent drug use

Adolescence is characterized by heightened risk-taking, including substance misuse. These behavioral patterns are influenced by ontogenic changes in neurotransmitter systems, particularly the dopamine system, which is fundamentally involved in the neural coding of reward and motivated approach behavior. During adolescence, this system evidences a peak in activity. At the same time, the dopamine (DA) system is neuroplastically altered by substance abuse, impacting subsequent function. Here, we describe properties of the dopamine system that change with typical adolescent development and that are altered with substance abuse. Much of this work has been gleaned from animal models due to limitations in measuring dopamine in pediatric samples. Structural and functional neuroimaging techniques have been used to examine structures that are heavily DA-innervated; they measure morphological and functional changes with age and with drug exposure. Presenting marijuana abuse as an exemplar, we consider recent findings that support an adolescent peak in DA-driven reward-seeking behavior and related deviations in motivational systems that are associated with marijuana abuse/dependence. Clinicians are advised that (1) chronic adolescent marijuana use may lead to deficiencies in incentive motivation, (2) that this state is due to marijuana's interactions with the developing DA system, and (3) that treatment strategies should be directed to remediating resultant deficiencies in goal-directed activity.

Medical marijuana laws and adolescent marijuana use in the USA from 1991 to 2014: results from annual, repeated cross-sectional surveys

Adolescent use of marijuana is associated with adverse later effects, so the identification of factors underlying adolescent use is of substantial public health importance. The relationship between US state laws that permit marijuana for medical purposes and adolescent marijuana use has been controversial. Such laws could convey a message about marijuana acceptability that increases its use soon after passage, even if implementation is delayed or the law narrowly restricts its use. We used 24 years of national data from the USA to examine the relationship between state medical marijuana laws and adolescent use of marijuana. Using a multistage, random-sampling design with replacement, the Monitoring the Future study conducts annual national surveys of 8th, 10th, and 12th-grade students (modal ages 13-14, 15-16, and 17-18 years, respectively), in around 400 schools per year. Students complete self-administered questionnaires that include questions on marijuana use. We analysed data from 1 098 270 adolescents surveyed between 1991 and 2014. The primary outcome of this analysis was any marijuana use in the previous 30 days. We used multilevel regression modelling with adolescents nested within states to examine two questions. The first was whether marijuana use was higher overall in states that ever passed a medical marijuana law up to 2014. The second was whether the risk of marijuana use changed after passage of medical marijuana laws. Control covariates included individual, school, and state-level characteristics. Marijuana use was more prevalent in states that passed a medical marijuana law any time up to 2014 than in other states (adjusted prevalence 15·87% vs 13·27%; adjusted odds ratio [OR] 1·27, 95% CI 1·07-1·51; p=0·0057). However, the risk of marijuana use in states before passing medical marijuana laws did not differ significantly from the risk after medical marijuana laws were passed (adjusted prevalence 16·25% vs 15·45%; adjusted OR 0·92, 95% CI 0·82-1·04; p=0·185). Results were generally robust across sensitivity analyses, including redefining marijuana use as any use in the previous year or frequency of use, and reanalysing medical marijuana laws for delayed effects or for variation in provisions for dispensaries. Our findings, consistent with previous evidence, suggest that passage of state medical marijuana laws does not increase adolescent use of marijuana. However, overall, adolescent use is higher in states that ever passed such a law than in other states. State-level risk factors other than medical marijuana laws could contribute to both marijuana use and the passage of medical marijuana laws, and such factors warrant investigation. US National Institute on Drug Abuse, Columbia University Mailman School of Public Health, New York State Psychiatric Institute.

Medical marijuana does not increase adolescent marijuana use

Medical marijuana does not increase adolescent marijuana use

The Effectiveness of Family Interventions in Preventing Adolescent Illicit Drug Use: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

In order to quantify the effectiveness of family interventions in preventing and reducing adolescent illicit drug use, we conducted a systematic review and meta-analysis of randomized controlled trials. We searched the Cochrane Database of Systematic Reviews, Educational Research Information Centre (ERIC), MEDLINE, Embase, and PsycINFO for studies published between 1995 and 2013. Results were described separately for different outcomes (marijuana vs. other illicit drugs) and intervention types (universal, selective, and indicated prevention). Meta-analyses were performed when data were sufficient (e.g., marijuana and other illicit drug initiation in universal samples), using random effect models. Otherwise, we provided narrative reviews (e.g., regarding selective and indicated prevention). Thirty-nine papers describing 22 RCTs were eligible for inclusion. Universal family interventions targeting parent-child dyads are likely to be effective in preventing (OR 0.72; 95% CI 0.56, 0.94) and reducing adolescent marijuana use, but not in preventing other illicit drugs (OR 0.90; 95% CI 0.60, 1.34). Among high-risk groups, there is no clear evidence for the effectiveness of family interventions in preventing and reducing illicit drug use and drug disorders. The three small RCTs among substance-(ab)using adolescents gave some indication that programs might reduce the frequency of illicit drug use. Family interventions targeting parent-child dyads are likely to be effective in preventing and reducing adolescent marijuana use in general populations, but no evidence for other illicit drug use was found. We underline the need to strengthen the evidence base with more trials, especially among at-risk populations.

Sibling popularity: A moderator of sibling influence for adolescent substance use

Sibling substance use is a known correlate of adolescent substance use. Yet, not all siblings are equally influential. Sibling influence has been found to vary by age gap, sex and birth order. Little research, however, has investigated whether siblings' peer context is also a source of variation. The present study tested whether more popular siblings were more influential for adolescent use of cigarettes, alcohol and marijuana. Data were obtained from sibling pairs in the National Longitudinal Study of Adolescent Health. Findings indicate that older siblings have more influence on younger sibling marijuana use when they have more friends. These findings contribute to prior work examining which siblings are more influential and highlight the need to consider siblings as part of a greater peer context.

Unfazed or Dazed and Confused: Does Early Adolescent Marijuana Use Cause Sustained Impairments in Attention and Academic Functioning?

There is some suggestion that heavy marijuana use during early adolescence (prior to age 17) may cause significant impairments in attention and academic functioning that remain despite sustained periods of abstinence. However, no longitudinal studies have examined whether both male and female adolescents who engage in low (less than once a month) to moderate (at least once a monthly) marijuana use experience increased problems with attention and academic performance, and whether these problems remain following sustained abstinence. The current study used within-individual change models to control for all potential pre-existing and time-stable confounds when examining this potential causal association in two gender-specific longitudinal samples assessed annually from ages 11 to 16 (Pittsburgh Youth Study N = 479; Pittsburgh Girls Study N = 2296). Analyses also controlled for the potential influence of several pertinent time-varying factors (e.g., other substance use, peer delinquency). Prior to controlling for time-varying confounds, analyses indicated that adolescents tended to experience an increase in parent-reported attention and academic problems, relative to their pre-onset levels, during years when they used marijuana. After controlling for several time-varying confounds, only the association between marijuana use and attention problems in the sample of girls remained statistically significant. There was no evidence indicating that adolescents who used marijuana experienced lingering attention and academic problems, relative to their pre-onset levels, after abstaining from use for at least a year. These results suggest that adolescents who engage in low to moderate marijuana use experience an increase in observable attention and academic problems, but these problems appear to be minimal and are eliminated following sustained abstinence.

The effect of medical marijuana laws on adolescent and adult use of marijuana, alcohol, and other substances

We estimate the effect of medical marijuana laws (MMLs) in ten states between 2004 and 2012 on adolescent and adult use of marijuana, alcohol, and other psychoactive substances. We find increases in the probability of current marijuana use, regular marijuana use and marijuana abuse/dependence among those aged 21 or above. We also find an increase in marijuana use initiation among those aged 12–20. For those aged 21 or above, MMLs further increase the frequency of binge drinking. MMLs have no discernible impact on drinking behavior for those aged 12–20, or the use of other psychoactive substances in either age group.