Marijuana use among adolescents

Prefrontal cortical distribution of muscarinic M2 and cannabinoid-1 (CB1) receptors in adult male mice with or without chronic adolescent exposure to Δ9-tetrahydrocannabinol

Chronic adolescent administration of marijuana's major psychoactive compound, ∆9-tetrahydrocannabinol (Δ9-THC), produces adaptive changes in adult social and cognitive functions sustained by prelimbic prefrontal cortex (PL-PFC). Memory and learning processes in PL-PFC neurons can be regulated through cholinergic muscarinic-2 receptors (M2R) and modulated by activation of cannabinoid-1 receptors (CB1Rs) targeted by Δ9-THC. Thus, chronic exposure to Δ9-THC during adolescence may alter the expression and/or distribution of M2Rs in PL-PFC neurons receiving CB1R terminals. We tested this hypothesis by using electron microscopic dual CB1R and M2R immunolabeling in adult C57BL/6 J male mice that had received vehicle or escalating dose of Δ9-THC through adolescence. In vehicle controls, CB1R immunolabeling was mainly localized to axonal profiles virtually devoid of M2R but often apposing M2R-immunoreactive dendrites and dendritic spines. The dendrites received inputs from CB1R-labeled or unlabeled terminals, whereas spines received asymmetric synapses exclusively from axon terminals lacking CB1Rs. Adolescent Δ9-THC significantly increased plasmalemmal M2R-immunogold density exclusively in large dendrites receiving input from CB1R-labeled terminals. In contrast, cytoplasmic M2R-immunogold density decreased in small spines of the Δ9-THC-treated adult mice. We conclude that Δ9-THC engagement of CB1Rs during adolescence increases M2R plasmalemmal accumulation in large proximal dendrites and decreases M2R cytoplasmic expression in small spines of PL-PFC.

Assessing the impacts of daily Cannabis versus alcohol and methamphetamines on young Australians in youth AOD treatment

BACKGROUND

Cannabis is the most widely used illicit substance by Australian young people, including those engaged with youth alcohol and other drug (AOD) systems. While recreational cannabis use in young people may be a developmental activity for some, for others, this usage becomes regular and be associated with poorer long term outcomes. This study reports on the rates of cannabis use and co-existing psychosocial complexity factors in the Youth Needs Census (2013 and 2016) where workers report on all clients in the youth AOD system, a cohort considered highly vulnerable.

METHODS

Data was examined for two rounds of data collection for the Youth Needs Census, including 823 youth AOD service engaged young people in 2016 and 1000 AOD service engaged young people in 2013, to identify usage rates, psychosocial outcomes, and changes over time.

RESULTS

Daily use of cannabis alone significantly exceeded daily usage rates for methamphetamines, alcohol, and cannabis used alongside other substances. Daily cannabis use was significantly associated with mental health problems, employment problems, education problems, family problems, and housing problems. Daily cannabis use was associated with most psychosocial complexity factors to the same extent as daily methamphetamine use and daily alcohol use, with daily cannabis users only showing lower incidence of the drug-related harm measure. Notably, daily cannabis use also increased from 2013 (47.5%) to 2016 (54.2%).

CONCLUSIONS

It is imperative that the number of individuals using cannabis is considered alongside the severity of harm when assessing the social impact of this substance. Within cannabis users engaged with the youth AOD system, who often have high levels of psychosocial complexity, cannabis is used daily by a large proportion of these youths and may play a role in negatively impacting their lives.

Dynamic transitions between marijuana use and cigarette smoking among US adolescents and emerging adults

BACKGROUND

Marijuana and tobacco are considered two closely related substances. It is of great significance to understand the mutual impact of marijuana and cigarette use when more states in the US have legalized marijuana use.

OBJECTIVE

This study aims to investigate the transitions between marijuana and cigarette use among adolescents and emerging adults.

METHOD

Guided by the probabilistic discrete events systems (PDES) theory, a five-stage model with 21 transition paths was constructed to quantify dynamic transitions between marijuana and cigarette use. The five stages were NU: Never-user, MU: Current marijuana user, CU: Current cigarette user, MCU: Current marijuana-cigarette user, and FU: Former-user. The proposed five-stage PDES model was tested using the 2013 National Survey on Drug Use and Health data (N = 26,665, 50.45% male). Transition probabilities were estimated using the Moore-Penrose generalized inverse matrix method.

RESULT

Among the adolescents, 51.14% of the CUs transited to use marijuana (MCU/MU), higher than the proportion of those who first used marijuana and then transferred to cigarettes (MCU/CU) (41.66%). The quitting rates for MUs, CUs and MCUs were 29.38%, 25.93% and 27.76%, respectively. Of the total FUs, 31.90% transited to MUs, 17.06% to CUs, and 17.39% to MCUs. Among the young adults, more people progressed from MUs to CUs. Transition probabilities by single year of age were also estimated.

CONCLUSION

This is the first study to quantify marijuana-cigarette transitions. Study findings indicate more cigarette-to-marijuana transitions for adolescents and more marijuana-to-cigarette transitions for emerging adults. Future intervention programs should consider this age-related difference in marijuana-cigarette use transitions.

Local spatial clustering in youths' use of tobacco, alcohol, and marijuana in Boston

BACKGROUND

Understanding geographic variation in youth drug use is important for both identifying etiologic factors and planning prevention interventions. However, little research has examined spatial clustering of drug use among youths by using rigorous statistical methods.

OBJECTIVES

The purpose of this study was to examine spatial clustering of youth use of tobacco, alcohol, and marijuana.

METHODS

Responses on tobacco, alcohol, and marijuana use from 1,292 high school students ages 13-19 who provided complete residential addresses were drawn from the 2008 Boston Youth Survey Geospatial Dataset. Response options on past month use included "none," "1-2," "3-9," and "10 or more." The response rate for each substance was approximately 94%. Spatial clustering of youth drug use was assessed using the spatial Bernoulli model in the SatScan™ software package.

RESULTS

Approximately 12%, 36%, and 18% of youth reported any past-month use of tobacco, alcohol, and/or marijuana, respectively. Two clusters of elevated past tobacco use among Boston youths were generated, one of which was statistically significant. This cluster, located in the South Boston neighborhood, had a relative risk of 5.37 with a p-value of 0.00014. There was no significant localized spatial clustering in youth past alcohol or marijuana use in either the unadjusted or adjusted models.

CONCLUSION

Significant spatial clustering in youth tobacco use was found. Finding a significant cluster in the South Boston neighborhood provides reason for further investigation into neighborhood characteristics that may shape adolescents' substance use behaviors. This type of research can be used to evaluate the underlying reasons behind spatial clustering of youth substance and to target local drug abuse prevention interventions and use.

Hormonal status and age differentially affect tolerance to the disruptive effects of delta-9-tetrahydrocannabinol (Δ(9)-THC) on learning in female rats

The effects of hormone status and age on the development of tolerance to Δ(9)-THC were assessed in sham-operated (intact) or ovariectomized (OVX) female rats that received either intraperitoneal saline or 5.6 mg/kg of Δ(9)-THC daily from postnatal day (PD) 75-180 (early adulthood onward) or PD 35-140 (adolescence onward). During this time, the four groups for each age (i.e., intact/saline, intact/THC, OVX/saline, and OVX/THC) were trained in a learning and performance procedure and dose-effect curves were established for Δ(9)-THC (0.56-56 mg/kg) and the cannabinoid type-1 receptor (CB1R) antagonist rimonabant (0.32-10 mg/kg). Despite the persistence of small rate-decreasing and error-increasing effects in intact and OVX females from both ages during chronic Δ(9)-THC, all of the Δ(9)-THC groups developed tolerance. However, the magnitude of tolerance, as well as the effect of hormone status, varied with the age at which chronic Δ(9)-THC was initiated. There was no evidence of dependence in any of the groups. Hippocampal protein expression of CB1R, AHA1 (a co-chaperone of CB1R) and HSP90β (a molecular chaperone modulated by AHA-1) was affected more by OVX than chronic Δ(9)-THC; striatal protein expression was not consistently affected by either manipulation. Hippocampal brain-derived neurotrophic factor expression varied with age, hormone status, and chronic treatment. Thus, hormonal status differentially affects the development of tolerance to the disruptive effects of delta-9-tetrahydrocannabinol (Δ(9)-THC) on learning and performance behavior in adolescent, but not adult, female rats. These factors and their interactions also differentially affect cannabinoid signaling proteins in the hippocampus and striatum, and ultimately, neural plasticity.

Perceived neighborhood illicit drug selling, peer illicit drug disapproval and illicit drug use among U.S. high school seniors

BACKGROUND

This study examined associations between perceived neighborhood illicit drug selling, peer illicit drug disapproval and illicit drug use among a large nationally representative sample of U.S. high school seniors.

METHODS

Data come from Monitoring the Future (2007-2011), an annual cross-sectional survey of U.S. high school seniors. Students reported neighborhood illicit drug selling, friend drug disapproval towards marijuana and cocaine use, and past 12-month and past 30-day illicit drug use (N = 10,050). Multinomial logistic regression models were fit to explain use of 1) just marijuana, 2) one illicit drug other than marijuana, and 3) more than one illicit drug other than marijuana, compared to "no use".

RESULTS

Report of neighborhood illicit drug selling was associated with lower friend disapproval of marijuana and cocaine; e.g., those who reported seeing neighborhood sales "almost every day" were less likely to report their friends strongly disapproved of marijuana (adjusted odds ratio [AOR] = 0.38, 95% CI: 0.29, 0.49) compared to those who reported never seeing neighborhood drug selling and reported no disapproval. Perception of neighborhood illicit drug selling was also associated with past-year drug use and past-month drug use; e.g., those who reported seeing neighborhood sales "almost every day" were more likely to report 30-day use of more than one illicit drug (AOR = 11.11, 95% CI: 7.47, 16.52) compared to those who reported never seeing neighborhood drug selling and reported no 30-day use of illicit drugs.

CONCLUSIONS

Perceived neighborhood drug selling was associated with lower peer disapproval and more illicit drug use among a population-based nationally representative sample of U.S. high school seniors. Policy interventions to reduce "open" (visible) neighborhood drug selling (e.g., problem-oriented policing and modifications to the physical environment such as installing and monitoring surveillance cameras) may reduce illicit drug use and peer disapproval of illicit drugs.

Contributions of social influences and psychopathological factors to cannabis use and dependence in high-school students

Objectives: To evaluate the relative contributions of peers cannabis use or non use, parental approval of such use, adolescents' own beliefs about use, self-esteem, and depressive and symptoms of borderline personality disorder, in the prediction of cannabis use and dependence.

Method: Participants were 257 high-school students who completed questionnaires assessing cannabis use frequency, cannabis dependence, the number of peers using cannabis, the number of peers opposed to cannabis use, parental attitude toward cannabis use, participants' attitude toward use, self-esteem, depressive and borderline symptomatology. Logistic regression analyses were conducted to predict cannabis use, daily use and dependence.

Results: The number of peers using cannabis, participants' approval of cannabis use, and the intensity of symptoms of borderline personality disorder were risk factors for use whereas the number of peers opposed to cannabis use was a protective factor. Parental attitudes toward use and participants' depressive symptomatology were not significant independent predictors of use. There were no significant predictors of probable cannabis dependence.

Conclusion: To inform adolescents that a significant proportion of them disapprove of cannabis use may be an effective component of prevention of use. Symptoms of borderline personality disorder may account for the association between depression and cannabis use. The social influences and psychopathological factors evaluated in this study did not appear to play a major role in the development of cannabis dependence.

Neighborhood-level LGBT hate crimes and current illicit drug use among sexual minority youth

OBJECTIVE

To investigate whether past-30 day illicit drug use among sexual minority youth was more common in neighborhoods with a greater prevalence of hate crimes targeting lesbian, gay, bisexual, and transgender (LGBT, or sexual minority) individuals.

METHODS

We used a population-based survey of public school youth in Boston, Massachusetts, consisting of 1292 9th-12th grade students from the 2008 Boston Youth Survey Geospatial Dataset (sexual minority n=108). Data on LGBT hate crimes involving assaults or assaults and battery between 2005 and 2008 were obtained from the Boston Police Department and linked to youths' residential address. Youth reported past-30 day use of marijuana and other illicit drugs. Wilcoxon-Mann-Whitney tests and corresponding p-values were computed to assess differences in substance use by neighborhood-level LGBT assault hate crime rate among sexual minority youth (n=103).

RESULTS

The LGBT assault hate crime rate in the neighborhoods of sexual minority youth who reported current marijuana use was 23.7 per 100,000, compared to 12.9 per 100,000 for sexual minority youth who reported no marijuana use (p=0.04). No associations between LGBT assault hate crimes and marijuana use among heterosexual youth (p>0.05) or between sexual minority marijuana use and overall neighborhood-level violent and property crimes (p>0.05) were detected, providing evidence for result specificity.

CONCLUSIONS

We found a significantly greater prevalence of marijuana use among sexual minority youth in neighborhoods with a higher prevalence of LGBT assault hate crimes. These results suggest that neighborhood context (i.e., LGBT hate crimes) may contribute to sexual orientation disparities in marijuana use.

Chronic administration during early adulthood does not alter the hormonally-dependent disruptive effects of delta-9-tetrahydrocannabinol (Δ9-THC) on complex behavior in female rats

This study examined whether chronic Δ(9)-THC during early adulthood would produce the same hormonally-dependent deficits in learning that are produced by chronic Δ(9)-THC during adolescence. To do this, either sham-operated (intact) or ovariectomized (OVX) female rats received daily saline or 5.6 mg/kg of Δ(9)-THC i.p. for 40 days during early adulthood. Following chronic administration, and a drug-free period to train both a learning and performance task, acute dose-effect curves for Δ(9)-THC (0.56-10 mg/kg) were established in each of the four groups (intact/saline, intact/THC, OVX/saline and OVX/THC). The dependent measures of responding under the learning and performance tasks were the overall response rate and the percentage of errors. Although the history of OVX and chronic Δ(9)-THC in early adulthood did not significantly affect non-drug or baseline behavior under the tasks, acute administration of Δ(9)-THC produced both rate-decreasing and error-increasing effects on learning and performance behavior, and these effects were dependent on their hormone condition. More specifically, both intact groups were more sensitive to the rate-decreasing and error-increasing effects of Δ(9)-THC than the OVX groups irrespective of chronic Δ(9)-THC administration, as there was no significant main effect of chronic treatment and no significant interaction between chronic treatment (saline or Δ(9)-THC) and the dose of Δ(9)-THC administered as an adult. Post mortem examination of 10 brain regions also indicated there were significant differences in agonist-stimulated GTPγS binding across brain regions, but no significant effects of chronic treatment and no significant interaction between the chronic treatment and cannabinoid signaling. Thus, acute Δ(9)-THC produced hormonally-dependent effects on learning and performance behavior, but a period of chronic administration during early adulthood did not alter these effects significantly, which is contrary to what we and others have shown for chronic administration during adolescence.

Marijuana, bigeminal premature ventricular contractions and sluggish coronary flow: Are they related?

Premature ventricular contractions (PVCs) and slow coronary flow phenomenon (SCFP) are primarily separate entities. Each one of them has different characteristics and a diverse spectrum of presentation. However, and despite many suggested theories, a comprehensive understanding of the etiology of both of them is still a matter of debate. PVCs, which can be triggered by consuming cannabis (marijuana), and through decreasing the diastolic time (DT), can affect the slow blood flow found in SCFP even more and worsen the clinical picture in patients who have PVCs and SCFP. In this paper, we present a patient who uses marijuana and has PVCs and SCFP, try to address different aspects of PVCs and SCFP, pinpoint any suspected interaction between both of them and the role of marijuana in this context. .

Dopamine response to psychosocial stress in chronic cannabis users: a PET study with [11C]-+-PHNO

A number of addictions have been linked with decreased striatal dopamine (DA) receptor availability and DA release. Stress has a key role in cannabis craving, as well as in modulation of dopaminergic signaling. The present study aimed to assess DA release in response to a laboratory stress task with [(11)C]-(+)-PHNO positron emission tomography in cannabis users (CU). Thirteen healthy CU and 12 healthy volunteers (HV) were scanned during a sensorimotor control task (SMCT) and under a stress condition using the validated Montreal imaging stress task (MIST). The simplified reference tissue model (SRTM) was used to obtain binding potential (BP(ND)) in striatal subdivisions: limbic striatum (LST), associative striatum (AST), and sensorimotor striatum (SMST). Stress-induced DA release (indexed as a percentage of reduction in [(11)C]-(+)-PHNO BP (ND)) between CU and HV was tested with analysis of variance. SMCT BP(ND) was significantly higher in CU compared with HV in the AST (F=10.38, p=0.003), LST (F=4.95, p=0.036), SMST (F=4.33, p=0.048), and whole striatum (F=9.02, p=0.006). Percentage of displacement (change in BP(ND) between SMCT and MIST PET scans) was not significantly different across groups in any brain region, except in the GP (-5.03±14.6 in CU, compared with 6.15±12.1 in HV; F=4.39, p=0.049). Duration of cannabis use was significantly associated with stress-induced [(11)C]-(+)-PHNO displacement by endogenous DA in the LST (r=0.566, p=0.044), with no effect in any other brain region. In conclusion, despite an increase in striatal BP(ND) observed during the control task, chronic cannabis use is not associated with alterations in stress-induced DA release.

[Acute cannabis poisoning in a 10-month-old infant]

We describe a case of accidental cannabis poisoning in a 10-month-old girl, who presented with impaired consciousness, with drowsiness and restlessness, generalized hypotonia, and inadequate smiles. No circulatory or respiratory problems were observed. Initial investigations were not informative (blood biology, CT scan, and cerebrospinal fluid examination), while the main causes of coma (meningoencephalitis, head trauma, metabolic disorders) were excluded. Questioning the parents led to suspecting accidental ingestion of a piece of cannabis, which was confirmed by the detection of high blood and urine levels of cannabinoid derivatives. Management was symptomatic and the clinical course, marked by the occurrence of agitation and irritability episodes lasting up to H18, led to complete regression of symptoms. Because of the high consumption in France, pediatric poisoning by cannabis seems increasingly common. The toxic levels in children are unknown however. Diagnosis is based on questioning and the search for cannabinoid derivatives in urine. In children, clinical symptoms are more expressive compared to adults, with neurological (drowsiness, agitation, abnormal behavior, ataxia, hypotonia, coma, and convulsions) or cardiopulmonary (tachycardia, bradypnea, apnea) or homeostatic presentations (hypothermia). Treatment in children is essentially symptomatic but sometimes requires active resuscitation. Recommendations are based on clinical monitoring the first 24h after intoxication and on medicosocial support.

Adolescent substance use disorders in the school setting

Adolescent substance use is a major public health problem that concerns parents, schools, clinicians, and policy makers. The authors review school-based prevention programs, school drug policies, clinical signs and symptoms of substance impairment, recommendations for referral and engaging adolescents who are using substances, and treatment interventions for adolescent substance use disorders.

Chronic cannabinoid administration to periadolescent rats modulates the metabolic response to acute cocaine in the adult brain

PURPOSE

To analyze brain metabolic response to acute cocaine in male and female Wistar rats with or without a history of cannabinoid exposure during periadolescence.

PROCEDURES

The synthetic cannabinoid agonist CP 55,940 (CP) or its vehicle (VH), were administered to male and female rats during periadolescence. When these animals reached adulthood, saline and cocaine-induced changes in 2-deoxy-2-[¹⁸F]fluoro-D-: glucose (FDG) uptake were studied by positron emission tomography.

RESULTS

The baseline (post-saline) metabolism in the septal nuclei was higher in CP-females than in VH-females, although septal metabolism was lower in CP-females after cocaine, reaching similar values to those of VH-females at baseline. Cocaine did not affect metabolism in VH-females. Periadolescent cannabinoid treatment did not influence baseline metabolism in males although cocaine reduced the FDG uptake in the dorsal striatum of males that received the VH but not CP.

CONCLUSIONS

These results suggest that cannabinoids during periadolescence modify baseline and cocaine-evoked brain metabolism in a sex-dependent manner. In the case of CP-females, the involvement of septal metabolic alterations in their susceptibility to the rewarding effects of cocaine should be further investigated.

Long-term behavioral and pharmacodynamic effects of delta-9-tetrahydrocannabinol in female rats depend on ovarian hormone status

Abuse of Δ⁹-THC by females during adolescence may produce long-term deficits in complex behavioral processes such as learning, and these deficits may be affected by the presence of ovarian hormones. To assess this possibility, 40 injections of saline or 5.6 mg/kg of Δ⁹-THC were administered i.p. daily during adolescence to gonadally intact or ovariectomized (OVX) female rats, yielding four treatment groups (intact/saline, intact/THC, OVX/saline, and OVX/ THC). Δ⁹-THC (0.56-10 mg/kg) was then re-administered to each of the four groups during adulthood to examine their sensitivity to its disruptive effects. The behavioral task required adult subjects to both learn (acquisition component) different response sequences and repeat a known response sequence (performance component) daily. During baseline (no injection) and control (saline injection) sessions, OVX subjects had significantly higher response rates and lower percentages of error in both behavioral components than the intact groups irrespective of saline or Δ⁹-THC administration during adolescence; the intact group that received Δ⁹-THC had the lowest response rates in each component. Upon re-administration of Δ⁹-THC, the groups that received adolescent ovariectomy alone, adolescent Δ⁹-THC administration alone, or both treatments were found to be less sensitive to the rate-decreasing effects, and more sensitive to the error-increasing effects of Δ⁹-THC than the control group (i.e. intact subjects that received saline during adolescence). Neurochemical analyses of the brains from each adolescent-treated group indicated that there were also persistent effects on cannabinoid type-1 (CB-1) receptor levels in the hippocampus and striatum that depended on the brain region and the presence of ovarian hormones. In addition, autoradiographic analyses of the brains from adolescent-treated, but behaviorally naïve, subjects indicated that ovariectomy and Δ⁹-THC administration produced effects on receptor coupling in some of the same brain regions. In summary, chronic administration of Δ⁹-THC during adolescence in female rats produced long-term effects on operant learning and performance tasks and on the cannabinoid system that were mediated by the presence of ovarian hormones, and that altered their sensitivity to Δ⁹-THC as adults.

A meta-analytic review of school-based prevention for cannabis use

This investigation used meta-analytic techniques to evaluate the effectiveness of school-based prevention programming in reducing cannabis use among youth aged 12 to 19. It summarized the results from 15 studies published in peer-reviewed journals since 1999 and identified features that influenced program effectiveness. The results from the set of 15 studies indicated that these school-based programs had a positive impact on reducing students' cannabis use (d = 0.58, CI: 0.55, 0.62) compared to control conditions. Findings revealed that programs incorporating elements of several prevention models were significantly more effective than were those based on only a social influence model. Programs that were longer in duration (≥15 sessions) and facilitated by individuals other than teachers in an interactive manner also yielded stronger effects. The results also suggested that programs targeting high school students were more effective than were those aimed at middle-school students. Implications for school-based prevention programming are discussed.

Development of cannabinoid 1 receptor protein and messenger RNA in monkey dorsolateral prefrontal cortex

Adolescent cannabis use is associated with an increased risk of schizophrenia and with impairments in cognitive processes reliant on the circuitry of the dorsolateral prefrontal cortex (DLPFC). Additionally, maternal cannabis use is associated with cognitive dysfunction in offspring. The effects of cannabis are mediated by the cannabinoid 1 receptor (CB1R), which is present in high density in the primate DLPFC. In order to determine how developmental changes in CB1Rs might render DLPFC circuitry vulnerable to cannabis exposure, we examined the density and innervation patterns of CB1R-immunoreactive (IR) axons and the expression of CB1R mRNA in the DLPFC from 81 macaque monkeys, ranging in age from embryonic 82 days to 18 years. Overall CB1R immunoreactivity in the gray matter robustly increased during the perinatal period and achieved adult levels by 1 week postnatal. However, laminar analyses revealed that CB1R-IR axon density significantly decreased with age in layers 1-2 but significantly increased in layer 4, especially during adolescence. In contrast, CB1R mRNA levels were highest 1 week postnatal, declined over the next 2 months, and then remained unchanged into adulthood. These findings provide a potential substrate for discrete, age-dependent effects of cannabis exposure on the maturation of primate DLPFC circuitry.

Exposure to cannabis in popular music and cannabis use among adolescents

BACKGROUND

Cannabis use is referenced frequently in American popular music, yet it remains uncertain whether exposure to these references is associated with actual cannabis use. We aimed to determine if exposure to cannabis in popular music is associated independently with current cannabis use in a cohort of urban adolescents.

METHODS

We surveyed all 9th grade students at three large US urban high schools. We estimated participants' exposure to lyrics referent to cannabis with overall music exposure and content analyses of their favorite artists' songs. Outcomes included current (past 30 days) and ever use of cannabis. We used multivariable regression to assess independent associations between exposures and outcomes while controlling for important covariates.

RESULTS

Each of the 959 participants was exposed to an estimated 27 cannabis references per day [correction added on 19 January 2010, after first online publication: 40 has been changed to 27] (standard deviation = 73 [correction added on 19 January 2010, after first online publication: 104 has been changed to 73]). Twelve per cent (n = 108) were current cannabis users and 32% (n = 286) had ever used cannabis. Compared with those in the lowest tertile of total cannabis exposure in music, those in the highest tertile of exposure were almost twice as likely to have used cannabis in the past 30 days (odds ratio = 1.83; 95% confidence interval = 1.04, 3.22), even after adjusting for socio-demographic variables, personality characteristics and parenting style. As expected, however, there was no significant relationship between our cannabis exposure variable and a sham outcome variable of alcohol use.

CONCLUSIONS

This study supports an independent association between exposure to cannabis in popular music and early cannabis use among urban American adolescents.

Cannabis consumption initiation among adolescents: a longitudinal study

This study aimed to investigate factors related to initiation of cannabis consumption among adolescents. A questionnaire was administered to 2043 14-15-year-olds from Barcelona who were followed-up and re-interviewed after 15 months. A bivariate analysis was performed to identify the factors associated with consumption, and multivariate logistic regression was carried out to model cannabis initiation. Among matched students, 23.7% of non-users at baseline had started to consume 15 months later (23.0% boys and 24.2% girls). Among those who had reported occasional cannabis use, 30.3% reported consumption during the previous month at the follow-up survey. Factors associated with cannabis initiation among boys and girls were smoking, risky alcohol use and intention to consume cannabis. Among boys, other associated factors were frequenting bars or discotheques and not having organized activities in leisure time. Among girls, another risk factor for initiation was having cannabis-using friends. Cannabis initiation was facilitated by legal drug use, favorable attitudes and context-related variables. These results highlight the role of behavioral and contextual variables and support the importance of reinforcing social skills in preventive programs.

Relative contributions of acculturation and psychopathological factors to cannabis use among adolescents from migrant parents

Immigrant adolescents and adolescents born of immigrant parents are at increased risk of substance use which has been linked to difficulties in acculturation processes. However very few studies have examined the role of the different acculturation strategies and none of them have controlled for relevant psychopathological and socio-familial factors. The aim of this study was to investigate the role of acculturation in cannabis use in a sample of adolescents born of immigrant parents taking into account potential confounding variables. A sample of 292 high school students born in France from at least one foreign parent completed a questionnaire assessing cannabis use, acculturation orientations, ethnic identity and the most relevant potential confounders (depressive symptoms, sensation seeking, borderline and psychopathic traits, alcohol and tobacco use, parental attachment, life events, socioeconomic status and academic achievement). A regression analysis showed that acculturation orientations and ethnic identity explained a significant part of the variance in the frequency of cannabis use. Individualism, integration and assimilation were negatively associated with the frequency of cannabis use suggesting they might serve as protective factors.

Marijuana: use among young males and health outcomes

Marijuana is the most commonly used illicit drug by adolescents and young adults, with more males than females reporting marijuana use. The adolescent and young adult years represent a critical period for interventions to prevent marijuana use and abuse. This article reviews relevant literature, including trends in young males' marijuana use and health effects of marijuana use. By most measures, there has been little net change in marijuana use among 12th graders and young adults since the 1990s. Despite males' greater use, little research has examined gender differences in areas such as metabolism of marijuana and long-term impact of marijuana use. In many areas, including dental health, fertility, and respiratory function, research is either sparse or has yielded conflicting results. Similarly, research on marijuana's carcinogenic effects has yielded conflicting results; however, a small but consistent literature indicates that marijuana use is linked to cancers unique to males. A stronger literature has identified an association between marijuana use and psychiatric problems. Clinical and program interventions for adolescents have potential to prevent marijuana use, as well as screen for and treat marijuana abuse. Improved research is needed, such as research with greater consistency in defining levels of use and greater emphasis on gender differences. Such research would help clinical and program interventions focus on those most at risk for adverse outcomes.

Chronic periadolescent cannabinoid treatment enhances adult hippocampal PSA-NCAM expression in male Wistar rats but only has marginal effects on anxiety, learning and memory

Pubertal and adolescent exposure to cannabinoids is associated with enduring alterations in anxiety and memory. However, periadolescence virtually remains unexplored. Here, we measured anxiety in the Elevated Plus Maze (EPM) in adult Wistar rats treated at periadolescence (P28-P38) with the cannabinoid agonist CP 55,940 (CP) (0.4 mg/kg; 2 ml/kg i.p., 1 daily injection), and we also defined their recognition memory in the novel object paradigm and spatial learning and memory in the water maze. Additionally, we measured the expression of hippocampal PSA-NCAM (Polysialic Acid-Neural Cell Adhesion Molecule) and long-term potentiation (LTP) as well as, given their role in mnemonic processing, the levels of plasma corticosterone and estradiol. We found that CP had no robust effects on anxiety or in recognition memory. In the water maze, only a slight decreased percentage of failed trials in the reference memory task and an improvement in an indirect index of attention were observed. However, we detected an up-regulation of hippocampal PSA-NCAM expression, only in CP-males, although this effect was not related to changes in LTP. No hormonal alterations were evident. Based on our data, minimal long-term effects on anxiety, learning and memory appear to result from cannabinoid exposure during the periadolescent period.

Endocannabinoid system: emerging role from neurodevelopment to neurodegeneration

The endocannabinoid system, including endogenous ligands ('endocannabinoids' ECs), their receptors, synthesizing and degrading enzymes, as well as transporter molecules, has been detected from the earliest stages of embryonic development and throughout pre- and postnatal development. ECs are bioactive lipids, which comprise amides, esters and ethers of long chain polyunsaturated fatty acids. Anandamide (N-arachidonoylethanolamine; AEA) and 2-arachidonoylglycerol (2-AG) are the best studied ECs, and act as agonists of cannabinoid receptors. Thus, AEA and 2-AG mimic several pharmacological effects of the exogenous cannabinoid delta9-tetrahydrocannabinol (Delta(9)-THC), the psychoactive principle of cannabis sativa preparations like hashish and marijuana. Recently, however, several lines of evidence have suggested that the EC system may play an important role in early neuronal development as well as a widespread role in neurodegeneration disorders. Many of the effects of cannabinoids and ECs are mediated by two G protein-coupled receptors (GPCRs), CB1 and CB2, although additional receptors may be implicated. Both CB1 and CB2 couple primarily to inhibitory G proteins and are subject to the same pharmacological influences as other GPCRs. This new system is briefly presented in this review, in order to put in a better perspective the role of the EC pathway from neurodevelopment to neurodegenerative disorders, like Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. In addition, the potential exploitation of antagonists of CB1 receptors, or of inhibitors of EC metabolism, as next-generation therapeutics is discussed.

Functional consequences of marijuana use in adolescents

Nearly half of 12th graders have tried marijuana, and 6% use daily. This paper reviews studies on neuropsychological functioning, brain structure, brain function, and subjective and objective measures of sleep in relation to adolescent marijuana use. Adolescents who use marijuana heavily tend to show disadvantaged attention, learning, and processing speed; subtle abnormalities in brain structure; increased activation during cognitive tasks despite intact performance; and compromised objective indicators of sleep quality. Some abnormalities appear to persist beyond a month of abstinence, but may resolve within three months if cessation is maintained. Recommendations for future studies include characterizing these indices in youth prior to the onset of marijuana use then examining change after chronic use has started, and using large samples of youth with varying degrees of involvement with marijuana as well as alcohol, nicotine, and other drugs to characterize the interactive influences on neurocognition and neural health.

Media exposure and marijuana and alcohol use among adolescents

We aimed to determine which media exposures are most strongly associated with marijuana and alcohol use among adolescents. In 2004, we surveyed 1,211 students at a large high school in suburban Pittsburgh regarding substance use, exposure to entertainment media, and covariates. Of the respondents, 52% were female, 8% were non-White, 27% reported smoking marijuana, and 60% reported using alcohol. They reported average exposure to 8.6 hr of media daily. In adjusted models, exposure to music was independently associated with marijuana use, but exposure to movies was independently associated with alcohol use. Implications, limitations, and suggestions for further research are discussed.

Stress-related factors in cannabis use and misuse: implications for prevention and treatment

We examined the role of stress as a risk factor and motivation for cannabis use/misuse. A systematic review of studies gathered from PsychINFO and MEDLINE databases was conducted. Findings suggest that cannabis is commonly used as a stress-coping strategy. Negative life events, trauma, and maladaptive coping were all related to consumption. Cannabis use for stress-coping purposes was most evident when examining chronic as compared with experimental use. Although many individuals may be able to use cannabis without consequences, there appears to be a subset of individuals who experience greater life stress and who may be more likely to use for stress-coping purposes. These individuals may be at greatest risk for addiction. Chronic use may potentiate stress-related motivation to use/abuse cannabis and is associated with decision-making deficits and alterations in brain-stress pathways that may exacerbate compulsive drug seeking and sensitize individuals to stress-related drug use. Overall, stress-coping interventions and harm reduction focused on reducing the amount ingested may facilitate prevention and recovery efforts.

Chronic delta 9-tetrahydrocannabinol during adolescence provokes sex-dependent changes in the emotional profile in adult rats: behavioral and biochemical correlates

Few and often contradictory reports exist on the long-term neurobiological consequences of cannabinoid consumption in adolescents. The endocannabinoid system plays an important role during the different stages of brain development as cannabinoids influence the release and action of different neurotransmitters and promote neurogenesis. This study tested whether long-lasting interference by cannabinoids with the developing endogenous cannabinoid system during adolescence caused persistent behavioral alterations in adult rats. Adolescent female and male rats were treated with increasing doses of Delta(9)-tetrahydrocannabinol (THC) for 11 days (postnatal day (PND) 35-45) and left undisturbed until adulthood (PND 75) when behavioral and biochemical assays were carried out. CB1 receptor level and CB1/G-protein coupling were significantly reduced by THC exposure in the amygdala (Amyg), ventral tegmental area (VTA) and nucleus accumbens (NAc) of female rats, whereas male rats had significant alterations only in the amygdala and hippocampal formation. Neither female nor male rats showed any changes in anxiety responses (elevated plus maze and open-field tests) but female rats presented significant 'behavioral despair' (forced swim test) paralleled by anhedonia (sucrose preference). In contrast, male rats showed no behavioral despair but did present anhedonia. This different behavioral picture was supported by biochemical parameters of depression, namely CREB alteration. Only female rats had low CREB activity in the hippocampal formation and prefrontal cortex and high activity in the NAc paralleled by increases in dynorphin expression. These results suggest that heavy cannabis consumption in adolescence may induce subtle alterations in the emotional circuit in female rats, ending in depressive-like behavior, whereas male rats show altered sensitivity to rewarding stimuli.

Long lasting consequences of cannabis exposure in adolescence

Despite the increasing use of cannabis among adolescents, there are little and often contradictory studies on the long-term neurobiological consequences of cannabis consumption in juveniles. Adolescence is a critical phase for cerebral development, where the endocannabinoid system plays an important role influencing the release and action of different neurotransmitters. Therefore, a strong stimulation by the psychoactive component of marijuana, delta-9-tetrahydrocanabinol (THC), might lead to subtle but lasting neurobiological changes that can affect adult brain functions and behaviour. The literature here summarized by use of experimental animal models, puts forward that heavy cannabis consumption in adolescence may induce subtle changes in the adult brain circuits ending in altered emotional and cognitive performance, enhanced vulnerability for the use of more harmful drugs of abuse in selected individuals, and may represent a risk factor for developing schizophrenia in adulthood. Therefore, the potential problems arising in relation to marijuana consumption in adolescence suggest that this developmental phase is a vulnerable period for persistent adverse effects of cannabinoids.

Augmented acquisition of cocaine self-administration and altered brain glucose metabolism in adult female but not male rats exposed to a cannabinoid agonist during adolescence

Marijuana consumption during adolescence has been proposed to be a stepping-stone for adult cocaine addiction. However, experimental evidence for this hypothesis is missing. In this work we chronically injected male and female Wistar rats with either the cannabinoid agonist CP 55,940 (CP; 0.4 mg/kg) or its corresponding vehicle. Adult acquisition (seven 30 min daily sessions) and maintenance (fourteen 2 h daily sessions) of cocaine self-administration (1 mg/kg), food-reinforced operant learning under conditions of normal (ad libitum access to food), and high motivation (food-restriction schedule) were measured. Additionally, brain metabolic activity was analyzed by means of [(18)F]-fluorodeoxyglucose positron emission tomography. During the acquisition phase, female CP-treated rats showed a higher rate of cocaine self-administration as compared to vehicle-treated females and males; no differences were found between both male groups. This effect disappeared in the maintenance phase. Moreover, no differences among groups were evident in the food-reinforced operant task, pointing to the cocaine-specific nature of the effect seen in self-administration rather than a general change in reward processing. Basal brain metabolic activity also changed in CP-treated females when compared to their vehicle-treated counterparts with no differences being found in the males; more specifically we observed a hyper activation of the frontal cortex and a hypo activation of the amygdalo-entorhinal cortex. Our results suggest that a chronic exposure to cannabinoids during adolescence alters the susceptibility to acquire cocaine self-administration, in a sex-specific fashion. This increased susceptibility could be related to the changes in brain metabolic activity induced by cannabinoids during adolescence.

Sex-dependent effects of periadolescent exposure to the cannabinoid agonist CP-55,940 on morphine self-administration behaviour and the endogenous opioid system

Early cannabinoid consumption may predispose individuals to the misuse of addictive drugs later in life. However, there is a lack of experimental evidence as to whether cannabinoid exposure during adolescence might differently affect opiate reinforcing efficacy and the opioid system in adults of both sexes. Our aim was to examine whether periadolescent chronic exposure to the cannabinoid agonist CP-55,940 could exert sex-dependent effects on morphine reinforcing and the opioid system in adulthood. Morphine reinforcing was studied under a progressive ratio (PR) reinforcement schedule in adult male and female rats that previously acquired morphine self-administration under a fixed ratio 1 (FR1) schedule. Binding levels and functionality of mu-opioid receptors were also evaluated. Periadolescent cannabinoid exposure altered morphine self-administration and the opioid system in adult rats in a sex-dependent manner. CP-55,940-exposed males exhibited higher self-administration rates under a FR1, but not under a PR schedule. In females, CP-55,940 did not modify morphine self-administration under either schedule. Moreover, CP-55,940 also increased mu-opioid receptor levels in the subcallosal streak of pre-treated animals and decreased mu-opioid receptor functionality in the nucleus accumbens shell but again, only in males. Our data indicate that adult male rats exposed to the cannabinoid in adolescence self-administer more morphine than females, but only when the demands required by the schedule of reinforcement are low, which might be related to the decrease in mu-opioid receptor functionality in the NAcc-shell observed in these animals.

Cannabis use and suicidal behaviours in high-school students

The aim of the study was to evaluate the relative contributions of cannabis use, depressive and anxious symptoms in the prediction of suicidal behaviors. Participants were 248 high-school students who completed questionnaires assessing cannabis use, suicidal behaviors, depressive and anxious symptoms. Cannabis use was a significant independent predictor of suicidal behaviors after adjustment for depressive and anxious symptoms.

EEG of chronic marijuana users during abstinence: relationship to years of marijuana use, cerebral blood flow and thyroid function

OBJECTIVE

Marijuana abuse is associated with neurological changes including increases in frontal EEG alpha during abstinence. Research is needed to assess to what extent these EEG patterns are indicative of cerebral perfusion deficits.

METHODS

We recorded the resting eyes closed EEG of 75 abstinent marijuana users and 33 control subjects. Fifty-six marijuana users used marijuana for less than eight years and 19 used for eight years or more. The EEG evaluation occurred within 72h of admission to an inpatient unit. Fifty-nine marijuana users remained abstinent for a month and were tested twice. Supplemental psychological and physiological data were also collected.

RESULTS

Log alpha2 and beta2 power at posterior sites were significantly lower for the marijuana abusers that used eight years or more than the other marijuana abusers and the control subjects. These EEG changes continued for the month of abstinence. The marijuana users who used marijuana for more than eight years, also, had lower heart rates and thyroid function (T4) compared to the other marijuana users and the control subjects.

CONCLUSIONS

Chronic marijuana use was also associated with reduced EEG power in alpha and beta bands at posterior sites. These reductions in EEG power appear to be related to cerebral perfusion deficits and/or thyroid function in marijuana abusers.

SIGNIFICANCE

Our results suggest EEG, cerebral blood flow velocity, cardiovascular and thyroid function alterations in marijuana abuser with an extended period of use. These alterations reflect under arousal in these systems.

Contributions of social influences and expectations of use to cannabis use in high-school students

The aim of the study was to evaluate the relative contributions of peers cannabis use or non-use, parental approval of such use, adolescents' own beliefs about use, to the prediction of cannabis use. The participants were 559 high-school students who completed questionnaires assessing the frequency of cannabis use, the number of peers using cannabis, the number of peers opposed to cannabis use, parental attitude toward cannabis use, and participants' expectations towards use. The number of peers using cannabis and participants' positive expectations of cannabis use were risk factors for use whereas the number of peers opposed to cannabis use and the negative expectations of use were protective factors. Parental attitudes towards use were not a significant independent predictor of use.

Psychiatry in orthodontics. Part 2: Substance abuse among adolescents and its relevance to orthodontic practice

Substance abuse by adolescents is a serious problem that will touch every orthodontic practice. Recent data show that 40% of tenth graders in the United States will use an illicit drug at some time, and 18% will do so in a 30-day period. These are significant figures that should impact orthodontic diagnosis and treatment planning. The nature of orthodontic treatment is unique in that the orthodontist will see relatively healthy adolescent patients on a monthly basis over a period of years. The orthodontist is in a prime position to recognize potential substance abuse problems and make referrals. This article discusses various types of substance abuse, diagnosis, options for referral, and orthodontic implications.

The marijuana withdrawal syndrome: diagnosis and treatment

A subset of marijuana smokers develop a cannabis use disorder and seek treatment for their marijuana use on their own initiative. A less well-known consequence of daily, repeated marijuana use is a withdrawal syndrome, characterized by a time-dependent constellation of symptoms: irritability, anxiety, marijuana craving, decreased quality and quantity of sleep, and decreased food intake. Treatment studies show that rates of continuous abstinence are low (comparable to relapse rates for other abused drugs), and more treatment options are needed. The objective of this review is to update clinicians on the current state of marijuana research and to describe features of marijuana withdrawal to facilitate the diagnosis and treatment of cannabis use disorders.

Behavioural and neuroendocrine effects of cannabinoids in critical developmental periods

The present article focuses on psychoneuroendocrine effects of cannabinoids in developing animals, with special emphasis on the perinatal, periweanling and periadolescent periods. We describe and discuss published data dealing with acute and long-term effects of exposure to cannabinoid agonists in such critical periods. Human studies have demonstrated that the consumption of marijuana by women during pregnancy affects the neurobehavioural development of their children. Investigations using animal models provide useful information for a better understanding of the long-lasting deleterious consequences of cannabis exposure during pregnancy and lactation. The increasing use of cannabis among adolescents and its associated public health problems have led to a parallel increase in basic research on appropriate animal models. Chronic administration of cannabinoid agonists during the periadolescent period causes persistent behavioural alterations in adult animals. Some of these alterations may be related to a possible increased risk of psychosis and other neuropsychiatric disorders in early onset cannabis users.

Drug addiction: the neurobiology of behaviour gone awry

Drug addiction manifests as a compulsive drive to take a drug despite serious adverse consequences. This aberrant behaviour has traditionally been viewed as bad "choices" that are made voluntarily by the addict. However, recent studies have shown that repeated drug use leads to long-lasting changes in the brain that undermine voluntary control. This, combined with new knowledge of how environmental, genetic and developmental factors contribute to addiction, should bring about changes in our approach to the prevention and treatment of addiction.

Office recognition and management of adolescent substance abuse

PURPOSE OF REVIEW

Substance misuse and substance use disorders are important pediatric public health concerns. The prevalence is high, beginning in adolescence through adulthood, and there is marked morbidity. This is especially true in the adolescent population, in whom the three leading causes of death are all associated with substance abuse. The primary care physician is ideally situated to recognize, prevent, and triage significant substance abuse problems. This review will provide recent, relevant information for primary care physicians (PCP) to enable them to have the current knowledge, tools, and attitudes needed to address these issues.

RECENT FINDINGS

Epidemiologic studies continue to document the widespread use of licit and illicit substances by youth. Understanding of substance use disorders is moving forward with an increasing clarity of the multiple factors important in the development of these disorders. This has already led to the establishment of effective prevention programs, which may be applicable to the primary care setting. Research into psychosocial treatment is proceeding rapidly, and psychopharmacologic approaches are also being investigated. Evidence-supported approaches to treatment now exist.

SUMMARY

Substance abuse in youth is a serious public health problem, with significant morbidity and mortality. The primary care physician can make major inroads into effective prevention and treatment by recognizing and addressing these issues in the outpatient office setting.

Chronic treatment with CP 55,940 during the peri-adolescent period differentially affects the behavioural responses of male and female rats in adulthood

RATIONALE

Despite the increasing use of cannabis among adolescents, there is scarce information about the long-term effects of cannabinoid receptor agonists in appropriate animal models.

OBJECTIVES

We aimed to investigate the behavioural features of adult male and female Wistar rats that had been exposed to a chronic treatment with the cannabinoid receptor agonist CP 55,940 (CP) during the juvenile period.

METHODS

CP (0.4 mg/kg i.p.) or its corresponding vehicle was administered once daily, from day 35 to day 45. In adulthood, the animals were tested in the holeboard, the open field and the elevated plus-maze, under different stress (illumination) conditions. After a resting period, the serum corticosterone levels (radioimmunoassay) of the animals were measured. The effects of CP on food intake and somatic growth were monitored throughout the experimental period.

RESULTS

The CP treatment induced significant sex-dependent effects on holeboard activity, as well as a decrease in the level of emotionality/anxiety in the open field and in the plus-maze. The animals receiving CP also showed diminished food intake and body weights during the treatment period, but both parameters recovered normal values during the period after treatment. No significant effect of the CP treatment on corticosterone levels was found.

CONCLUSIONS

The results demonstrate that chronic administration of CP during the peri-adolescent period resulted in marked behavioural effects in adulthood. The nature of these effects depended on the sex of the animals and on the specific behavioural test. The possible neurobiological substrates underlying the effects of CP are discussed.

Substance abuse in adolescents: a complex conundrum for the clinician

Substance abuse remains a complex and pervasive conundrum for society and for clinicians seeking to improve the lives of their pediatric patients. Substance abuse is linked to the human instinct for pleasure at any cost and is fueled by enticing encouragement of the media teaching society to seek drug-induced pleasure without fear of negative consequences. Other complications are the limited education about psychoactive substances provided to youth and the health care profession pledged to serve them. Primary care clinicians must provide their adolescent patients with adequate screening and counseling about substance abuse. Treatment of the substance-abusing patient is often a combination of behavioral interventions (including family therapy), and, in limited situations, addiction-specific medications. Research suggests that female drug addicts have a better outcome in female-only drug treatment programs. In addition, new drugs are being developed that target specific brain mechanisms involved in drug addiction; these drugs will have less toxicity and less abuse potential than illicit drugs such as cocaine. Vaccines are being developed that will block the effects of such drugs as cocaine and PCP. Medications developed for the treatment of depression and epilepsy will be a source of medications for the treatment of drug addiction. The study of endorphins and the neurobiology of stress and substance abuse promise to develop potent anti-addiction chemicals, greatly aiding in the war on drug abuse.

The intoxicated child

Psychiatric disorders and substance abuse occur frequently together, which leads to difficulty in assessment and treatment. An awareness of the prevalence and manifestations of psychiatric diagnoses is essential for the quality treatment of adolescents who abuse substances. The clinician should keep up-to-date on psychopharmacologic interventions [65, 83]. Frequently, the use of psychiatric medications, such as antidepressants, mood stabilizers, and psychostimulants, is beneficial. Care must be taken, however, to avoid potential interactions between the illicit drugs and the prescribed medications [151]. Use of groups such as Alcoholics Anonymous, Narcotics Anonymous, or "Double-Trouble" groups, which deal with mentally ill and chemical abusing or dual diagnosis issues, often can be a useful adjunct to treatment with a mental health professional [152-154]. Careful observation, history taking, and appropriate consultation result in better detection and treatment of comorbid medical and psychiatric disorders and the initial substance abuse problem.