Initiation Of Cannabis Use Research Articles

A Cross-Sectional and Prospective Comparison of Medicinal Cannabis Users and Controls on Self-Reported Health.

Introduction: Despite widespread legalization, the impact of medicinal cannabis use on patient-level health and quality of life (QOL) has not been carefully evaluated. The objective of this study was to characterize self-reported demographics, health characteristics, QOL, and health care utilization of Cannabis Users compared with Controls.Methods: A longitudinal, cross-sectional web-based survey study was completed between April 2016 and February 2018. Study participants (n=1276) were a convenience sample of either patients with a diagnosed health condition or caregivers of a patient with a diagnosed health condition registered with the Realm of Caring Foundation (a nonprofit organization dedicated to therapeutic cannabis research and education). Participants were invited through e-mail to complete follow-up assessments every 3 months with 33% of participants completing one or more prospective follow-ups. Assessments included self-reported demographics, health care utilization, medication use, pain, anxiety, depression, sleep, and QOL. Cannabis Users (n=808) were compared with Controls (n=468) using negative binomial regression and linear mixed effects models testing the effect of initiation, cessation, and maintenance of medicinal cannabis use.Results: Cannabis Users self-reported significantly better QOL [t(1054)=−4.19, p<0.001], greater health satisfaction [t(1045)=−4.14, p<0.001], improved sleep [children: t(224)=2.90, p<0.01; adults: [t(758)=3.03, p<0.01], lower average pain severity [t(1150)=2.34, p<0.05], lower anxiety [t(1151)=4.38, p<0.001], and lower depression [t(1210)=5.77, p<0.001] compared with Controls. Cannabis Users reported using fewer prescription medications (rate ratio [RR]=0.86; 95% confidence interval [CI]: 0.77–0.96) and were less likely to have a past-month emergency department visit (RR=0.61; 95% CI: 0.44–0.84) or hospital admission (RR=0.54; 95% CI: 0.34–0.87). Controls who initiated cannabis use after baseline showed significant health improvements at follow-up, and the magnitude of improvement mirrored the between-group differences observed at baseline.Conclusions: Cannabis use was associated with improved health and QOL. Longitudinal testing suggests that group differences may be due to the medicinal use of cannabis. Although bias related to preexisting beliefs regarding the health benefits of cannabis in this sample should be considered, these findings indicate that clinical trials evaluating the efficacy of defined cannabinoid products for specific health conditions are warranted.

Cognitive Function Impairments Linked to Alcohol and Cannabis Use During Adolescence: A Study of Gender Differences.

Major neurocognitive changes occur during adolescence, making this phase one of the most critical developmental periods of life. Furthermore, this phase in life is also the time in which youth substance use begins. Several studies have demonstrated the differential associations of alcohol and cannabis use concerning the neurocognitive functioning of both males and females. Past and contemporary literature on gender-specific effects in neuroscience of addiction is predominantly based on cross-sectional datasets and data that is limited in terms of measurement variability. Given the importance of gender-specific effects in addiction studies, and in order to address the two above-mentioned gaps in the literature, the present study aimed to compare neurocognitive functioning of male and female adolescents in the context of cannabis and alcohol use, while employing a longitudinal design with multiple repeated measurements. Participants were 3,826 high school students (47% female; mean age, 12.7), who were recruited from 31 high schools in the greater Montreal area. Participants were requested to complete annual surveys for five consecutive years, from 7th to 11th grade, assessing their alcohol/cannabis use and neurocognitive functioning (working memory, delayed recall memory, perceptual reasoning, and inhibition control). The analytical strategy focused on the longitudinal association between each predictor (female, male) and each of the outcomes (domains of neurocognitive functioning). Multilevel linear models assessed the association of alcohol and cannabis consumption and the four domains of neurocognitive functioning. Results revealed a gender by within-subject interaction, suggesting a weaker effect of yearly fluctuation of cannabis use on working memory among males compared to females. Our findings suggest a different pattern of neurocognitive impairment of female and male working memory after using cannabis over the course of adolescence. Early initiation of cannabis use potentially results in more spatial working memory deficits in female adolescents. This may negatively influence young females’ capacity in academic settings and lead to significant impairment in adulthood, which critically decreases the individual’s quality of life.

Endocannabinoid genetic variation enhances vulnerability to THC reward in adolescent female mice.

Adolescence represents a developmental period with the highest risk for initiating cannabis use. Little is known about whether genetic variation in the endocannabinoid system alters mesolimbic reward circuitry to produce vulnerability to the rewarding properties of the exogenous cannabinoid Δ9-tetrahydrocannabinol (THC). Using a genetic knock-in mouse model (FAAHC/A) that biologically recapitulates the human polymorphism associated with problematic drug use, we find that in adolescent female mice, but not male mice, this FAAH polymorphism enhances the mesolimbic dopamine circuitry projecting from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) and alters cannabinoid receptor 1 (CB1R) levels at inhibitory and excitatory terminals in the VTA. These developmental changes collectively increase vulnerability of adolescent female FAAHC/A mice to THC preference that persists into adulthood. Together, these findings suggest that this endocannabinoid genetic variant is a contributing factor for increased susceptibility to cannabis dependence in adolescent females.

Cessation of cannabis use: A retrospective cohort study

Given recent findings of a worldwide increase in cannabis use, a better understanding of the factors associated with cannabis use is needed. Most previous studies have focused on factors that predict the initiation of cannabis use, but less is known about factors associated with cessation. The present study is a retrospective cohort study of 6467 current or former cannabis users aged 15 to 46 years (mean age 22.5, SD = 4.8). Data were collected via an online survey advertised in social media. All analyzed participants had used cannabis for at least three years. Approximately 16.3% (n = 1055) of the sample population had not used cannabis in the previous 12 months and were classified as quitters; all others (83.7%, n = 5412) reported at least monthly use. Cessation was predicted by older current age, being female, nonmigrant status, less sensation seeking, using psychological treatment, more peer cannabis use during youth and more negative first experience with cannabis. An additional predictor was a nonincrease in the frequency of cannabis use in the first three years of use, indicating that trajectories of cannabis use are set early on and might be used to identify risk groups for early preventive measures.

Grey Matter Volume Differences Associated with Extremely Low Levels of Cannabis Use in Adolescence.

Rates of cannabis use among adolescents are high, and are increasing concurrent with changes in the legal status of marijuana and societal attitudes regarding its use. Recreational cannabis use is understudied, especially in the adolescent period when neural maturation may make users particularly vulnerable to the effects of Δ-9-tetrahydrocannabinol (THC) on brain structure. In the current study, we used voxel-based morphometry to compare gray matter volume (GMV) in forty-six 14-year-old human adolescents (males and females) with just one or two instances of cannabis use and carefully matched THC-naive controls. We identified extensive regions in the bilateral medial temporal lobes as well as the bilateral posterior cingulate, lingual gyri, and cerebellum that showed greater GMV in the cannabis users. Analysis of longitudinal data confirmed that GMV differences were unlikely to precede cannabis use. GMV in the temporal regions was associated with contemporaneous performance on the Perceptual Reasoning Index and with future generalized anxiety symptoms in the cannabis users. The distribution of GMV effects mapped onto biomarkers of the endogenous cannabinoid system providing insight into possible mechanisms for these effects.SIGNIFICANCE STATEMENT Almost 35% of American 10th graders have reported using cannabis and existing research suggests that initiation of cannabis use in adolescence is associated with long-term neurocognitive effects. We understand very little about the earliest effects of cannabis use, however, because most research is conducted in adults with a heavy pattern of lifetime use. This study presents evidence suggesting structural brain and cognitive effects of just one or two instances of cannabis use in adolescence. Converging evidence suggests a role for the endocannabinoid system in these effects. This research is particularly timely as the legal status of cannabis is changing in many jurisdictions and the perceived risk by youth associated with smoking cannabis has declined in recent years.

First Time Cannabis Use and Sexual Debut in U.S. High School Adolescents

PurposeUse of illicit drugs by adolescents might facilitate or trigger other risky behaviors, including early sexual initiation (ESI), multiple partners, and unprotected sex. This study examines whether the age at which adolescents initiate cannabis use is associated with the age of their first sexual intercourse in the U.S. in 2015. MethodsA secondary analysis of data from the 2015 Youth Risk Behavior Surveillance Survey, a cross-sectional, nationally representative survey, was conducted (n = 7,664). Exposure of interest was age of initiation of cannabis use (never used cannabis, age 12 or younger, 13–14 years of age, and age 15 or older) and outcome was ESI (14 years old or younger). Unadjusted and adjusted odds ratios (OR) and their 95% confidence intervals were computed. ResultsPrevalence of ESI was 15.3%. The proportion of cannabis use was 39.9%. Adolescents starting cannabis use before the age of 15 had higher adjusted odds of ESI (OR ranged 4.2–6.7). This association is modified by sex: while in boys using cannabis before 13 years, the OR is 9 (95% CI 5.2–15.6); in girls, it is 2.8 (95% CI 1.7–4.7). ConclusionsOur findings suggest that there should be sex and drug education programs instituted before the age of 12 ideally, and no later than by age 15 since this time represents a critical period of initiating both behaviors.

The Effect of Age of Initiation of Cannabis Use on Psychosis, Depression, and Anxiety among Youth under 25 Years

This study was conducted to review the current state of evidence on the association between age of initiation of cannabis use and symptoms of psychosis, depression, or anxiety among youth under 25 years of age. We conducted a systematic review of articles published prior to March 2018 by searching OVID MEDLINE, PsycINFO, EMBASE, and the references of included studies. We included comparative studies (cohort, case-control, cross-sectional) that reported on cannabis use in persons <25 years of age (exposure) and symptoms of psychosis, depression, or anxiety (outcome). We narratively synthesized the studies according to design (cohort, etc.) and psychiatric outcome. We used the Newcastle-Ottawa Scale to assess risk of bias. Of the 534 citations identified through the literature search, 23 met the eligibility criteria and were included in this review. With psychosis as the outcome, all except one study found that earlier cannabis use was generally associated with higher risks. With depression/anxiety as the outcome, 6 of the 11 included studies reported findings indicating that earlier use of cannabis was linked to higher symptom levels. In persons <25 years old, greater cannabis use is associated with more psychological symptoms, especially among those with a predisposition or existing vulnerability to such outcomes (Oxford Centre for Evidence-Based Medicine level 3 or 4). Policy makers need to consider the adverse effects of cannabis use in youth when planning a public health approach to cannabis legalization.

Sex, THC, and hormones: Effects on density and sensitivity of CB1 cannabinoid receptors in rats

BackgroundThe recent NIH mandate to consider sex as a biological variable in preclinical research has focused attention on delineation of sex differences in behavior. To investigate mechanisms underlying sex differences in Δ9-tetrahydrocannabinol (THC) effects, we examined the effects of sex and gonadal hormones on CB1 receptors in cerebellum, hippocampus, prefrontal cortex, and striatum. MethodsAdult Sprague-Dawley rats underwent gonadectomy (GDX) or sham-GDX. Half of the GDX females and males received estradiol or testosterone replacement (GDX+H), respectively. All rats were injected with vehicle or 30 mg/kg THC twice daily for 1 week before brain collection. CP55,940-stimulated [35S]GTPγS and [3H]SR141716A saturation binding assays were performed. ResultsWith exception of enhanced receptor activation in the hippocampi of female rats compared to males, vehicle-treated rats exhibited minimal sex differences in CB1 receptor densities or G-protein coupling. Repeated treatment with THC resulted in pronounced CB1 receptor desensitization and downregulation in both sexes in all brain regions with a greater magnitude of change in females. ConclusionsThese results suggest that sex differences in the density and G-protein coupling of brain CB1 receptors may play a limited role in sex differences in acute THC effects not mediated by the hippocampus. In contrast, sex differences after repeated THC were common, with females (intact, GDX, and GDX+H) showing greater downregulation or desensitization in all four brain regions compared to the respective male groups. This result is consistent with a finding that women tend to progress to tolerance and dependence quicker than men after initiation of cannabis use.

The initiation of cannabis use in adolescence is predicted by sex-specific psychosocial and neurobiological features.

Cannabis use initiated during adolescence might precipitate negative consequences in adulthood. Thus, predicting adolescent cannabis use prior to any exposure will inform the aetiology of substance abuse by disentangling predictors from consequences of use. In this prediction study, data were drawn from the IMAGEN sample, a longitudinal study of adolescence. All selected participants (n=1,581) were cannabis-naïve at age 14. Those reporting any cannabis use (out of six ordinal use levels) by age 16 were included in the outcome group (N=365, males n=207). Cannabis-naïve participants at age 14 and 16 were included in the comparison group (N=1,216, males n=538). Psychosocial, brain and genetic features were measured at age 14 prior to any exposure. Cross-validated regularized logistic regressions for each use level by sex were used to perform feature selection and obtain prediction error statistics on independent observations. Predictors were probed for sex- and drug-specificity using post-hoc logistic regressions. Models reliably predicted use as indicated by satisfactory prediction error statistics, and contained psychosocial features common to both sexes. However, males and females exhibited distinct brain predictors that failed to predict use in the opposite sex or predict binge drinking in independent samples of same-sex participants. Collapsed across sex, genetic variation on catecholamine and opioid receptors marginally predicted use. Using machine learning techniques applied to a large multimodal dataset, we identified a risk profile containing psychosocial and sex-specific brain prognostic markers, which were likely to precede and influence cannabis initiation.

Gender differences in the factors associated with early age of initiation of cannabis use in Jamaica

ABSTRACTObjective: This study aimed to examine the gender differences in the factors associated with early age of cannabis use. Methods: Secondary data analysis was done on the National Housing Survey 2016. Descriptive statistics consisted of computation of sociodemographic characteristics and Pearson’s Chi Square. Multivariate analysis of factors associated with age of debut of cannabis use was done using binary logistic regression. Results: Of the 4,623 participants, 54.8% were females. The mean age of initiation (AOI) of cannabis use for the sample was 16.89 years (standard deviation [SD]: 5.06); males 16.03 years (SD: 4.39), and females 18.96 years (SD: 5.92). Male Rastafarians, but not females, had higher odds of early cannabis use debut compared to those who have no religion adjusted odds ratio (AOR): 2.33, 95% confidence interval [CI]: 1.04–5.19). Married as well as single females, but not males, were significantly less likely to have had early cannabis use debut compared to the divorced/separated ones (AOR: 0.06, 95% CI: 0.01–0.53; AOR: 0.08, 95% CI: 0.01–0.73, respectively). There was a significant positive association between primary/lower educational level and early AOI for females (AOI: 4.48, 95% CI: 1.51–15.20), but not for males. Conclusion: There were significant gender differences in the factors associated with early initiation of cannabis use in the Jamaican population.

Associations of Father's Lifetime Cannabis Use Disorder with Child's Initiation of Cannabis Use, Alcohol Use, and Sexual Intercourse by Child Gender

ABSTRACTBackground: Early initiation of alcohol use, cannabis use, and sexual intercourse among adolescents is an important public health concern in the United States. Parents' history of substance use disorder is an important contributing factor for children's problem behaviors. Objectives: The associations of fathers' lifetime cannabis use disorder with children's initiation of cannabis use, alcohol use, and sexual intercourse were examined. In addition, child's gender was considered as a moderator of each association. Methods: Data from two companion longitudinal studies was utilized, the Rochester Youth Developmental Study and its intergenerational extension, the Rochester Intergenerational Study. Multiple linear regression analyses were conducted to examine the associations of the father's lifetime cannabis use disorder with the child's initiation of cannabis use, alcohol use, and sexual intercourse. To test gender differences in the associations, the study sample was stratified by child's gender. Results: The average age of first cannabis use (b = –3.71, p < .05), alcohol use (b = –3.65, p < .05), and sexual intercourse (b = –2.94, p < .05) among daughters of fathers with a lifetime cannabis use disorder was lower than that of their counterparts after adjusting for all other control variables, whereas no significant differences were detected in a father–son relationship. Conclusions: Homotypic continuity of cannabis use, as well as heterotypic continuity from the father's cannabis use to the child's alcohol use and sexual intercourse existed in a father–daughter relationship. These findings suggest that family-based interventions for female adolescents whose father has suffered from a cannabis use disorder be developed to prevent better adolescents' early substance use and sexual intercourse.

Early Cannabis Use and Neurocognitive Risk: A Prospective Functional Neuroimaging Study

BackgroundRetrospective neuroimaging studies have suggested an association between early cannabis onset and later neurocognitive impairment. However, these studies have been limited in their ability to distinguish substance use risk factors from cannabis-induced effects on neurocognition. We used a prospective cohort design to test whether neurocognitive differences preceded cannabis onset (substance use risk model) and if early cannabis use was associated with poorer neurocognitive development (cannabis exposure model). MethodsParticipants (N = 85) completed a visuospatial working memory task during functional magnetic resonance imaging and multiple cognitive assessments (Wechsler Intelligence Scale for Children-IV, Cambridge Neuropsychological Test Automated Battery) at 12 years of age, before any reported cannabis use (baseline), and at 15 years of age (follow-up: N = 85 cognitive assessments, n = 67 neuroimaging). By follow-up, 22 participants reported using cannabis and/or failed a Δ9-tetrahydrocannabinol urine screen (users). ResultsAt baseline, group differences supported a risk model. Those who would initiate cannabis use by 15 years of age had activation differences in frontoparietal (increased) and visual association (decreased) regions and poorer executive planning scores (Stockings of Cambridge) compared with noninitiators. Limited support was found for a cannabis exposure model. At follow-up, activation in the cuneus displayed a significant cannabis dose-response relationship, although neither cannabis dose nor cuneus activation was associated with cognitive performance. ConclusionsThe purported neurocognitive effects of early cannabis onset may not be due to cannabis initiation alone but also driven by limitations or late development of neurocognitive systems predictive of substance use. In addition, more prolonged cannabis exposure may be required to observe the cognitive effects of early cannabis onset.

Patterns in adolescent cannabis use predict the onset and symptom structure of schizophrenia-spectrum disorder

This study investigated adolescent cannabis use as a risk factor for schizophrenia spectrum disorder (SSD). Motives for early cannabis use and resulting usage patterns were examined alongside clinical measures of SSD onset and symptomatology.Participants (N = 178) were recruited for two samples, 1: healthy controls (HC) with cannabis use, 2: schizophrenia patients (SSD) with cannabis use. Structured interviews of participants and family informants were used to obtain diagnostic and biographical information.Factor-analysis of reported motives for initiating cannabis use produced four groups; sedation, stimulation, social pressure, and recreation. Regression analyses revealed significant relationships between these groups and SSD. Most notably, reason group factor scores predict SSD risk as well as schizotypal symptom severity. Findings also indicate that these factors follow a hierarchical structure, which explains their relative involvement in increased SSD risk.We suggest that adolescent cannabis use both hastens the onset and amplifies the severity of SSD. In response we propose a model for identifying at risk individuals, predicting the onset and severity of SSD, and potentially mitigating the associated psychiatric impairments.

T203. ILLICIT DRUGS USE AND ULTRA-HIGH RISK (UHR) FOR PSYCHOSIS STATUS IN A LATIN-AMERICAN SAMPLE

BackgroundIn recent years, a number of investigations have evaluated the effect of cannabis use on the risk of presenting ultra-high risk for psychosis (UHR) status as well as its influences on transition rate, suggesting a dose-dependent interaction. On the other hand, the association between cocaine (snorted or smoked) - an increasing health issue in several countries worldwide - and the UHR state was not appropriately examined. Also, exposure to other psychotomimetic drugs, as amphetamines and lysergic acid diethylamide (LSD), has not been investigated yet. We sought to examine differences in the prevalence of drug use between UHR subjects and epidemiologic controls (EC).MethodsOver 2500 individuals from the city of São Paulo (Brazil), aged between 18 and 30 years old, were screened with the Prodromal Questionnaire. Subjects with scores higher than 18 points in the positive subscale were invited to be thoroughly assessed with the application of SIPS (Structured Interview for Psychosis-Risk Syndromes). Drug use (lifetime use, age of first use and more intense use) was assessed using South Westminster scale.Results100 individuals presented UHR state; other 110 were enrolled as EC. A subsample of 50 UHR subjects and 82 HC with data on drugs consumption were evaluated herein. UHR subjects history of lifetime drug use was: 19 (38%) cannabis; 5 (10%) snorted cocaine; 1 (2%) crack; 1 (2%) amphetamine; 2 (6.9%) LSD. EC history of lifetime drug use was: 20 (24.4%) cannabis; 6 (7.3%) snorted cocaine; 0 crack; 2 (2.4%) amphetamine; 1 (1.2%) LSD. No differences were observed for snorted cocaine (p=0.589), crack (p=0.379), amphetamine (p=1.0), or LSD (P=0.167). At a trend level, cannabis lifetime use (p=0.096) was more prevalent in the UHR group. Additional analyses showed that UHR subjects initiate cannabis use at earlier age than EC (p=0.006). In this group, 20% of subjects had used cannabis prior to 15 years of age, in comparison to 3.6% in the EC group.DiscussionOur results reinforce the view that cannabis use is linked to psychosis risk and that subjects at early age of exposure are at greatest risk. Nonetheless, studies with larger number of participants are warranted to confirm our findings, particularly on the lack of association between less frequently consumed drugs and the UHR for psychosis state.

Verbal Memory Performance and Reduced Cortical Thickness of Brain Regions Along the Uncinate Fasciculus in Young Adult Cannabis Users.

Introduction: Memory impairment is one of the most commonly reported effects of cannabis use, especially among those who initiate use earlier, perhaps due to the effects of delta-9- tetrahydrocannabinol on cannabinoid (CB1) receptors in the brain. Studies have increasingly investigated whether cannabis use is associated with impairments in verbal memory, and with alterations in brain structures underlying verbal memory. The uncinate fasciculus (UF), a long-range white matter tract, connects regions with densely localized CB1 receptors that are important in verbal memory. This study investigated the impact of cannabis use on UF structures and its association with memory performance in young adult cannabis users (CU) and non-using controls (CON).Materials and Methods: Nineteen CU and 22 CON completed a verbal memory task and a neuroimaging protocol, in which diffusion tensor imaging and structural scans were collected. We compared memory performance, diffusion and tractography measures of the UF, and cortical thickness of regions connected by the UF, between CU and CON. In regions showing a significant group effect, we also examined associations between verbal memory performance, cortical thickness, and age of onset of cannabis use.Results: Compared to non-users, CU had worse memory performance, decreased fiber bundle length in the UF, and decreased cortical thickness of brain regions along the UF such as the entorhinal cortex and fusiform gyrus. Verbal memory performance was significantly associated with age of onset of cannabis use, indicating that those who initiated cannabis use at an earlier age performed worse. Cortical thickness of the entorhinal cortex was significantly correlated with age of first use and memory performance.Conclusion: This study provides evidence that cannabis use, especially when initiated at a young age, may be associated with worse verbal memory and altered neural development along the UF. Reductions in cortical thickness in regions implicated in memory processes may underlie weaknesses in verbal memory performance.

Does Cannabis Use Cause Declines in Neuropsychological Functioning? A Review of Longitudinal Studies.

Cannabis use has been linked to impairments in neuropsychological functioning across a large and continually expanding body of research. Yet insight into underlying causal relations remains limited due to the historically cross-sectional nature of studies in this area. Recently, however, studies have begun to use more informative design strategies to delineate these associations. The aim of this article is to provide a critical evaluation and review of research that uses longitudinal designs to examine the link between cannabis use and neuropsychological functioning. In summarizing the primary findings across these studies, this review suggests that cannabis use leads to neuropsychological decline. However, across most studies, these associations were modest, were present only for the group with the heaviest cannabis use, and were often attenuated (or no longer significant) after controlling for potential confounding variables. Future studies with neuropsychological data before and after initiation of cannabis use, along with careful measurement and control of "shared risk factors" between cannabis use and poorer neuropsychological outcomes, are needed to better understand who, and under what conditions, is most vulnerable to cannabis-associated neuropsychological decline. (JINS, 2017, 23, 893-902).

Consumo de cannabis na adolescência: relato de caso

Introduction: The illicit use of drugs has increased among adolescents. These are a risk group and cannabis is the drug preferentially used. Drug abuse is a clinical indication for family assessment. The aim is to alert illicit drug use in adolescence and emphasize the importance of family assessment and brief intervention by the family doctor. Case description: A 18-year-old adolescent male, belonging to a nuclear family at stage V of the Duvall cycle and middle social class, living with his parents with deafness and a 14-year-old sister. Family history of alcoholism. Initiated cannabis use at age 16 and regular use motivated school failure. In April 2015 with complaints of irritability and loss of motivation, associated with lack of concentration. Complaints were justified by the revolt in relation to deaf parents. In Family Circle, the adolescent put his sister in the center of the family and parents apart. According to the Family APGAR, it was a family with moderate dysfunction. It was decided not to intervene with family because it was not considered a high-risk situation and to not go against the adolescent will. Advice was provided to drug abuse, adapted to the stage of change. In September 2015 stopped using cannabis, remaining abstinent in March 2016 and more motivated at school. The maintenance of abstinence and prevention of relapse were promoted. Comment: The family continues to be the most consistent social support. The family dynamics can be prejudiced when parents, especially deaf, deal with the problems of adolescents, increasing the risk of illicit drug use. The family assessment and evaluation of the motivation for change by the family doctor are essential because only in this way is possible to improve doctor-patient relationship and chances of therapeutic success.

Early cannabis initiation and educational attainment: is the association causal? Data from the French TEMPO study.

Adolescent cannabis use has been reported to predict later educational attainment; however, results of past studies may be confounded by inappropriate control for factors that make some youths more likely to use cannabis precociously than others. We aimed to test the possibility of a causal relationship between early cannabis initiation and later academic achievement. Analyses are based on data collected among TEMPO cohort study participants (France, 2009, n = 1103, 22-35 years). Participants were previously assessed in childhood (1991) and adolescence (1999); additionally, their parents had taken part in a longitudinal epidemiological cohort study (GAZEL). Early cannabis initiation was defined as use at age 16 or earlier. Educational attainment was defined as the completion of a high-school degree ('Baccalauréat'). Early (up to and including age 16 years) and late (after age 16 years) cannabis-use initiators were compared with non-users using logistic regression models controlled for inverse probability weights (IPWs) of exposure calculated based on participants' socio-demographic, juvenile and parental characteristics. In age- and sex-adjusted analyses, early cannabis initiators were more likely than non-users to have low educational attainment [odds ratio (OR): 1.77, 95% confidence interval (CI) 1.22-2.55]. In IPWs-controlled analyses, this association somewhat decreased (OR: 1.64, 95% CI 1.13-2.40). Late cannabis initiators did not have lower educational attainment than non-users. Early cannabis use and educational attainment appeared more strongly associated in young women than in young men. Early cannabis can cause low educational attainment. Youths who initiate cannabis use early require attention from addiction and education specialists to reduce their odds of poor long-term outcomes.

Short communication: Genetic association between schizophrenia and cannabis use

Background and aimPrevious studies have shown a relationship between schizophrenia and cannabis use. As both traits are substantially heritable, a shared genetic liability could explain the association. We use two recently developed genomics methods to investigate the genetic overlap between schizophrenia and cannabis use. MethodsFirstly, polygenic risk scores for schizophrenia were created based on summary statistics from the largest schizophrenia genome-wide association (GWA) meta-analysis to date. We analysed the association between these schizophrenia polygenic scores and multiple cannabis use phenotypes (lifetime use, regular use, age at initiation, and quantity and frequency of use) in a sample of 6,931 individuals. Secondly, we applied LD-score regression to the GWA summary statistics of schizophrenia and lifetime cannabis use to calculate the genome-wide genetic correlation. ResultsPolygenic risk scores for schizophrenia were significantly (α<0.05) associated with five of the eight cannabis use phenotypes, including lifetime use, regular use, and quantity of use, with risk scores explaining up to 0.5% of the variance. Associations were not significant for age at initiation of use and two measures of frequency of use analyzed in lifetime users only, potentially because of reduced power due to a smaller sample size. The LD-score regression revealed a significant genetic correlation of rg=0.22 (SE=0.07, p=0.003) between schizophrenia and lifetime cannabis use. ConclusionsCommon genetic variants underlying schizophrenia and lifetime cannabis use are partly overlapping. Individuals with a stronger genetic predisposition to schizophrenia are more likely to initiate cannabis use, use cannabis more regularly, and consume more cannabis over their lifetime.

The International Cannabis Consortium: What Did We Learn About The Genetics Of Cannabis Use

Background Cannabis is the most frequently used and abused illicit drug worldwide and cannabis (ab)use is associated with social, physical, and psychological problems. Twin and family studies have shown that cannabis use and abuse are heritable traits. The International Cannabis Consortium was initiated with the aim of identifying genetic risk variants for cannabis use phenotypes by meta-analysing data from many contributing cohorts. The (partly preliminary) results of the International Cannabis Consortium will be presented: genome-wide association (GWA) meta-analyses on lifetime cannabis use and age at initiation of use. Additionally, findings from several follow-up studies will be presented, including the genetic association of cannabis use with use of other substances, schizophrenia, and conduct disorder. Methods GWA analyses of lifetime cannabis use were performed by each contributing group independently (13 groups, total N=32,330) and were subsequently meta-analysed. We tested for replication, and the SNP results were used to perform a gene-based test of association. We also estimated the total SNP-based heritability and the genetic correlation between lifetime cannabis use and cigarette use based on LD-score regression analysis. Secondly, we meta-analysed GWA results of age at initiation of cannabis use from 8 groups (N=24,222) using a survival analysis. Again SNP results are followed up by a gene-based test of association and an estimate of SNP-based heritability. In follow-up projects, LD-score regression analyses were used to determine the genetic correlation of cannabis use with nicotine, alcohol, and caffeine use, as well as schizophrenia and conduct disorder. We also created polygenic risk scores for cannabis use in an independent target sample and determined to what extent these polygenic scores predicted conduct symptoms. Results Although none of the SNPs were significantly associated with lifetime cannabis use, the gene-based analysis identified 4 significantly associated genes, including NCAM1, CADM2, SCOC and KCNT2. Interestingly, NCAM1 was previously reported to be associated with nicotine and other substance use. All SNPs combined explained 20% of the liability of lifetime cannabis use. For age at initiation of cannabis use, we identified five SNPs (in high linkage-disequilibrium) that were genome-wide significant. Results of the gene-based test and SNP-based heritability are not available yet. Follow-up studies show a significant genetic correlation of cannabis use with smoking initiation, alcohol use per week, as well as with schizophrenia. Furthermore, polygenic risk scores for cannabis use were significantly associated with symptoms of conduct disorder. Discussion The findings of the two largest meta-analyses of GWA studies of cannabis use phenotypes are presented. Several interesting genetic loci were identified, revealing important new candidate genes for cannabis use. Future functional studies should explore the impact of the identified genes on the biological mechanisms of cannabis use. We also show that genes underlying cannabis use are in part overlapping with genes underlying use of other substances and mental health phenotypes, including nicotine and alcohol use, schizophrenia, and symptoms of conduct disorder.