Classes Of Substance Use Research Articles

Prenatal Substance Exposure and Infant Discharge Placement: Results From the ACT NOW Study.

It is critical that researchers gather evidence of factors that identify infants at risk of out-of-home placement based on types of substance exposures and demographic characteristics. This study applied a validated medical record data extraction tool on data derived from a multi-site (N = 30) pediatric clinical trials network (ISPCTN) study of Neonatal Opioid Withdrawal (ACT NOW study). Participants included 1808 birthing parent-infant dyads with documented NOWS scoring or prenatal opioid exposure. Non-Hispanic White pregnant persons comprised the largest proportion of the sample (69.8%), followed by Non-Hispanic Black (11.6%), Non-Hispanic Multiracial and Other race (8.5%), and Hispanic (6.2%). Most notably, infant prenatal substance exposure across alcohol, cocaine, meth/amphetamine, and opioids, had the lowest possibility of discharging to parent(s). Additionally, latent class analysis identified distinct classes of substance use during pregnancy that were associated with different probabilities of discharging to parent(s). Specifically, less than half of infants (47%-49%) in the Poly-use and Meth/amphetamine classes were discharged to their parent(s). Severity of infant withdrawal symptoms influenced placement decisions within the Poly-use and Prescription Opioid classes. Findings can inform standard practices for increasing support for pregnant persons and substance-exposed infants including identification, subsequent referrals, communication with Child Protective Services, and plans of safe care.

The Association of Stigma, School, and Family Factors with Patterns of Substance Use Among LGBTQ Youth.

Polysubstance use is associated with myriad short- and long-term health outcomes. Although prior research has documented differences in polysubstance use between lesbian, gay, bisexual, transgender, queer/questioning, and other sexual and gender minoritized (LGBTQ +) youth and their heterosexual/cisgender counterparts, as well as between subgroups of LGBTQ + youth, it is unknown how personal, family, and school factors are associated with substance use patterns among LGBTQ + youth. Using a large, national sample of 9646 LGBTQ + youth ages 13-17, we used latent class analysis to examine patterns of alcohol, tobacco, and marijuana use and to determine whether personal, family, and school factors predict class membership. We identified five classes of substance use: polysubstance use, polysubstance experimentation, dual alcohol and cannabis, alcohol, and no use. Greater depression and LGBTQ + victimization, and an ability to be oneself at school, were associated with greater odds of membership in the polysubstance use class, while higher levels of family connection and having a Gender Sexuality Alliance (GSA) at school were associated with lower odds of membership in the polysubstance use class. Our analysis also revealed sociodemographic differences in class membership. These findings highlight potential mechanisms for intervention to reduce polysubstance use among LGBTQ + youth.

Substance Use Over Time Among Sexual and Gender Minority People: Differences at the Intersection of Sex and Gender.

Purpose: Sexual and gender minority (SGM) people are at greater risk for substance use than heterosexual and cisgender people, but most prior work is limited by cross-sectional analyses or the examination of single substance use. This study examined substance use over time among SGM people to identify patterns of polysubstance use at the intersection of sex and gender. Methods: Data were collected annually over 4 years from SGM respondents (n = 11,822) in The Population Research in Identity and Disparities for Equality (PRIDE) Study. Differences in substance use patterns (any prior 30-day use of 15 substances) by gender subgroup were examined with latent class analysis, and multinomial regression models tested relationships between gender subgroup and substance use. Results: Eight classes of substance use were observed. The three most common patterns were low substance use (49%), heavy episodic alcohol use (≥5 alcoholic drinks on one occasion) with some cannabis and tobacco use (14%), and cannabis use with some tobacco and declining heavy episodic alcohol use (13%). Differences observed included lower odds of patterns defined by heavy episodic alcohol use with some cannabis and tobacco use in all gender subgroups relative to cisgender men and persons with low substance use (odds ratios [ORs] 0.26-0.60). Gender expansive people assigned female at birth, gender expansive people assigned male at birth, and transgender men had greater odds of reporting cannabis use with small percentages of heavy episodic alcohol and tobacco use (ORs: 1.41-1.60). Conclusion: This study suggests that there are unique patterns of polysubstance use over time among gender subgroups of SGM people.

Multiple Substance Use Patterns and Its Relationship with Imprisonment in a High-Risk Group of Iranian Adults.

Substance use is recognized as an important factor associated with many diseases and premature deaths and the main risk factor for disability worldwide. This study aims to identify subgroups of substance use in adults and detect the effect of imprisonment on the membership of participants in latent classes of substance use. Study Design: A cross-sectional study. This study was performed on 930 adult people who were referred to behavioral health counseling centers in Tehran province. All participants completed some checklists and questionnaires. Data analysis was performed using chi-square, Fisher's exact test, and latent class analysis (LCA). Four latent classes were identified, including non-users (58%), cigarette smokers (11.6%), users of low stigma substances (27.4%), and drug users (3.1%). After adjusting for other studied variables, having a history of imprisonment increased the odds of membership in the cigarette smoker class (Odds ratio [OR]=5.82, 95%, confidence interval [CI]: 3.19-10.63) and drug user class (OR=53.59, 95% CI: 18.00- 159.52) compared to non-user class. Among all participants, 84 (9.0%) had a history of imprisonment. Results from the present study indicate that 30.5% of the participants fell under the user of the low-stigma substance or drug user group. Focusing on increasing prisoner's knowledge of the dangers of using different substances and considering various programs for prisoners' leisure time may help reduce substance use prevalence.

Latent class analysis of substance use typologies associated with mental and sexual health outcomes among sexual and gender minority youth.

Little is known about sexual and gender minority youth (SGMY) who have sex with men's unique patterns of substance use, even though they are at risk for substance use and adverse mental and other health outcomes. We used latent class analysis to examine typologies of substance use and multinomial logistic regression to investigate mental health outcomes (depression and anxiety) and HIV/STI testing correlates associated with different classes of substance use in a sample of SGMY who have sex with men in the USA and use substances (n = 414) who participated in an online survey. The average age was 22.50 years old (SD = 3.22). A four-class solution was identified representing: 'depressant and stimulant use' (3.4%), 'high polysubstance use' (4.6%), 'low substance use with moderate cannabis use' (79.2%), and 'high cannabis, stimulant and alcohol use' (12.8%). Membership to a specified substance use class varied by age, previous arrest, gender identity, anxiety, and lifetime HIV testing. Multivariate logistic regression results indicated that participants in the high polysubstance use (AOR = 5.48, 95% CI 1.51, 19.97) and high cannabis use class (AOR = 3.87, 95% CI 1.25, 11.94) were significantly more likely than those in the low substance use with moderate cannabis use class to report previous arrest. Those in the high polysubstance use class were also significantly less likely to have been tested for HIV than those in the low substance use with moderate cannabis use class (AOR = 0.21, 95% CI 0.05, 0.93). Findings will guide the development and implementation of tailored approaches to addressing the intersection of substance use and HIV risk among SGMY.

Patterns of substance use and predictors of class membership among university male students: a latent class analysis

ABSTRACT Background This study aimed to identify latent classes of substance use and predictors of class membership. Methods This cross-sectional study was performed on 1894 Students. The sample was selected through multi-stage sampling from four universities. Latent class analysis was performed to achieve the study objectives. Results Three latent classes were identified; 1) non-user (68.1%), 2) sedative-hypnotic drug user (29.4%), and 3) polydrug user (2.5%%). Low self-esteem and low self-efficacy increased the odds of membership in sedative-hypnotic drug user and polydrug user compared to non-user class. Age (OR = 1.29), self-injury (OR = 1.93), having a physical fight (OR = 9.25), low self-esteem (OR = 1.88), and low self-efficacy (OR = 5.28) are associated with polydrug user class. Conclusion Focusing on enhancing self-efficacy and self-esteem with considering other related factors may help design and execute effective programs to reduce substance use among students.

Adolescents' Perceptions of Substance Use Harms are Contingent on Mode of Administration and Type of Substance.

Early vaping research often did not differentiate between substances vaped. The present study investigates risk perceptions for vaped nicotine and vaped cannabis. A school-based census of 9th and 11th graders yielded 431 responses to the California Healthy Kids Survey. Differences in harm perceptions were evaluated using multilevel mixed-effects models. Students were more likely to report nicotine vaping as great-moderate risk in comparison to cannabis vaping. Additionally, vaped cannabis was viewed as riskier than traditional administration. These results indicate that differences in harm perceptions may need to be addressed when targeting specific classes of substance use in investigations and interventions.

Associations between Longitudinal Patterns of Substance Use and Anxiety and Depression Symptoms among a Sample of Canadian Secondary School Students.

The objective of this study is to examine the longitudinal associations between latent classes of substance use and anxiety and depression scores among youth who use substances. This study uses data from three waves (Wave 1: 2017/18, Wave 2: 2018/19, and Wave 3: 2019/20) of the COMPASS study. Students in grades 9 and 10 who reported substance use at baseline (n = 738) report their substance use (alcohol, cannabis, cigarettes, and e-cigarettes) and anxiety and depression symptoms at each wave. A Repeated Measures Latent Class Analysis (RMLCA) is used to determine substance use classes, and mixed models are used to examine the associations between substance use classes and anxiety and depression. We identify three classes of substance use: (1) occasional alcohol and e-cigarette use, (2) escalating poly-substance use, and (3) consistent poly-substance use. After controlling for relevant covariates, consistent poly-substance use is associated with depression (Female OR: 1.24 [95%CI: 0.46, 2.02]; Male OR 1.13 [95%CI: 0.38, 1.87]) but not anxiety. Escalating poly-substance use is associated with depression among males (OR 0.72 [95%CI: 0.10, 1.33]). These findings should be taken into consideration when creating prevention programming and treatment strategies for adolescents. Substance use programming should be comprehensive, consider multiple substances, and be cognizant of symptoms of mental illness, particularly depression.

New psychoactives within polydrug use trajectories-evidence from a mixed-method longitudinal study.

AimsTo provide public health‐related research evidence on types and usage patterns of new psychoactive substances (NPS), developmental pathways into NPS and decision‐making factors for, and associated harms of, NPS use.DesignThree‐phase mixed‐methods design, including a latent class analysis (LCA) of the longitudinal Belfast Youth Development Study (BYDS), a narrative analysis of interviews with NPS users and a three‐step approach manual method modelling using regressions to reveal classes of substance use and their associated predictors and outcomes.SettingNorthern Ireland.ParticipantsA total of 2039 people who responded to the questions on ‘ever use’ of the drug variables included at wave 7 (aged 21 years) of the BYDS. Eighty‐four narrative interviews with NPS users.MeasurementsCategories of drug use identified by LCA. Predictors and outcomes included measures of family, partners, peers, substance use, school, delinquency and mental health.FindingsA four‐class solution provided the best fit for the data: alcohol; alcohol and tobacco; alcohol, tobacco and cannabis; and polydrug (the latter including NPS). The qualitative analysis yielded a taxonomy that distinguished how NPS operate within a wider range of drug repertoires from experimental to problematic.ConclusionsIn Northern Ireland, new psychoactive substances appear to be a feature of broader polydrug use rather than a standalone class of drug use.

Alcohol- and drug-related consequences across latent classes of substance use among American Indian adolescents

IntroductionSubstance use among American Indian (AI) adolescents is a significant public health concern, as they report greater health disparities related to substance use compared to other racial/ethnic groups. The present study examines differences across classes of substance use behaviors regarding alcohol- and drug-related consequences. MethodsThe current study was a secondary analysis of the dataset used by Stanley and Swaim (2018). AI adolescents (n = 3498, 47.8% female, Mage = 14.8) completed a survey including substance use and related consequences. Protocols were approved by institutional IRB, tribal authority, school boards, and parental consent/child assent were obtained. ResultsIn line with Stanley and Swaim (2018), we identified four classes of substance use: no past month substance use; marijuana and cigarette use only; alcohol, marijuana, and cigarette use only; and polysubstance use. Cross-class comparisons revealed that adolescents in classes characterized by the use of a greater number of substances also reported experiencing greater alcohol- and drug-related consequences with one exception: the class characterized by marijuana and cigarette use reported greater drug-related consequences compared to the class characterized by alcohol, marijuana, and cigarette use. ConclusionsAI adolescents who engage in the use of multiple substances should be provided with psychoeducation around the increased risk of associated negative consequences. Given the health disparity experienced by AI adolescents, interventions to alleviate the burden of negative consequences are necessary.

Examining risk behavior and syringe coverage among people who inject drugs accessing a syringe services program: A latent class analysis

IntroductionInjection drug use (IDU) remains a significant public health problem. IDU has been associated closely with the opioid crisis; driving overdose, HIV, and Hepatitis C (HCV) infection nationwide. Syringe services programs (SSPs) remain pivotal evidence-based interventions to reduce harm and engage subgroups of people who inject drugs (PWID). This study aims to provide policy considerations from the IDEA SSP, the first legal SSP in the state of Florida. MethodsWe performed a latent class analysis on patterns of substance use among participants (N = 982) newly enrolled in a syringe services program (SSP). Associations between classes of substance use and sociodemographic variables, risky injection and sex behaviors, HIV/HCV status and syringe coverage were analyzed using the R3STEP and BCH 3-step procedures in latent class regression. ResultsWe found a three-class solution: Heroin-Dominant class (73.9%), Methamphetamine-Dominant class (9.5%) and Heroin/Cocaine class (16.6%). Compared to Heroin-Dominant class, the Heroin/Cocaine class were more likely to report homelessness, sharing works, unprotected sex, public injection, and to be HCV positive. Compared to both Heroin-Dominant and Heroin/Cocaine classes, the Methamphetamine-Dominant class were more likely to be male, Hispanic, gay or bisexual orientation, HIV positive, to report unprotected sex and sex with PWID. In addition, the lowest and highest syringe coverage were among those in the Heroin/Cocaine and Methamphetamine-Dominant classes, respectively. ConclusionExisting interventions among this population to mitigate infectious disease risk, such as SSPs, can be a used to engage differing PWID populations. However, multi-component, targeted preventive interventions and need-based syringe distribution policies are required to further reduce HIV and HCV risk among various PWID populations.

Genetic and environmental risk factors in the non-medical use of over-the-counter or prescribed analgesics, and their relationship to major classes of licit and illicit substance use and misuse in a population-based sample of young adult twins.

The non-medical use of over-the-counter or prescribed analgesics (NMUA) is a significant public health problem. Little is known about the genetic and environmental etiology of NMUA and how these risks relate to other classes of substance use and misuse. Our aims were to estimate the heritability NMUA and sources of genetic and environmental covariance with cannabis and nicotine use, cannabis and alcohol use disorders and nicotine dependence in Australian twins. Biometrical genetic analyses or twin methods using structural equation univariate and multivariate modeling. Australia. A total of 2007 young adult twins [66% female; μage =25.9, standard deviation (SD)=3.6, range=18-38] from the Brisbane Longitudinal Twin Study retrospectively assessed between 2009 and 2016. Self-reported NMUA (non-opioid or opioid-based), life-time nicotine, cannabis and opioid use, DSM-V cannabis and alcohol use disorders and the Fagerström Test for Nicotine Dependence. Life-time NMUA was reported by 19.4% of the sample. Univariate heritability explained 46% [95% confidence interval (CI)=0.29-0.57] of the risks in NMUA. Multivariate analyses revealed that NMUA is moderately associated genetically with cannabis (rg =0.41) and nicotine (rg =0.45) use and nicotine dependence (rg =0.34). In contrast, the genetic correlations with cannabis (rg =0.15) and alcohol (rg =0.07) use disorders are weak. In young male and female adults in Australia, the non-medical use of over-the-counter or prescribed analgesics appears to have moderate heritability. NMUA is moderately associated with cannabis and nicotine use and nicotine dependence. Its genetic etiology is largely distinct from that of cannabis and alcohol use disorders.

Predictors of Substance Use Latent Classes Among American Indian Youth Attending Schools On or Near Reservations.

Identical latent classes of substance use for 7 to 8 grade and9 to 12 grade American Indian (AI) youth living on or near reservations suggest that patterns of substance use are established early among these youth. This study examines relationships of substance-related factors to latent class membership and whether these relationships differ by grade group. In-school surveys were administered to 1503 7 to 8 grade and 1995 9 to 12 grade students from 46 schools on or near reservations during the 2009/2010 to 2012/2013 school years. Four-class latent class models of substance use were specified and five classes of substance-related factors (peers, substance availability, perceived harm, family, early initiation), plus grade level and gender, were evaluated as predictors. For 7 to 8 grade students, substance-related factors differentiated nonusers from users, while for 9 to 12 graders, these factors also differentiated types of users. Early initiation and peer factors were strongly related to class membership, while other factors were less strongly related. Early initiation of alcohol or marijuana is strongly related to being in a substance-using class for AI youth. Because these youth tend to initiate use earlier that other US youth, prevention resources should be targeted to reaching them and their families before age 12. Predictors of latent classes of substance use were identified for reservation-based AI youth. While the classes were identical for 7 to 8 grade and 9 to 12 grade youth, predictors varied across grade group, which may inform how best to develop prevention efforts unique to middle and high school AI youth.

Association between polygenic risk for tobacco or alcohol consumption and liability to licit and illicit substance use in young Australian adults

BackgroundCo-morbid substance use is very common. Despite a historical focus using genetic epidemiology to investigate comorbid substance use and misuse, few studies have examined substance-substance associations using polygenic risk score (PRS) methods. MethodsUsing summary statistics from the largest substance use GWAS to date (258,797- 632,802 subjects), GWAS and Sequencing Consortium of Alcohol and Nicotine use (GSCAN), we constructed PRSs for smoking initiation (PRS-SI), age of initiation of regular smoking (PRS-AI), cigarettes per day (PRS-CPD), smoking cessation (PRS-SC), and drinks per week (PRS-DPW). We then estimated the fixed effect of individual PRSs on 22 lifetime substance use and substance use disorder phenotypes collected in an independent sample of 2463 young Australian adults using genetic restricted maximal likelihood (GREML) in Genome-wide Complex Trait Analysis (GCTA), separately in females, males and both sexes together. ResultsAfter accounting for multiple testing, PRS-SI significantly explained variation in the risk of cocaine (0.67%), amphetamine (1.54%), hallucinogens (0.72%), ecstasy (1.66%) and cannabis initiation (0.97%), as well as DSM-5 alcohol use disorder (0.72%). PRS-DPW explained 0.75%, 0.59% and 0.90% of the variation of cocaine, amphetamine and ecstasy initiation respectively. None of the 22 phenotypes including emergent classes of substance use were significantly predicted by PRS-AI, PRS-CPD, and PRS-SC. ConclusionsTo our knowledge, this is the first study to report significant genetic overlap between the polygenic risks for smoking initiation and alcohol consumption and the risk of initiating major classes of illicit substances. PRSs constructed from large discovery GWASs allows the detection of novel genetic associations.

Alcohol, Prescription Drug Misuse, Sexual Violence, and Dating Violence Among High School Youth

PurposeSexual violence (SV), teen dating violence (TDV), and substance use are significant public health concerns among U.S. adolescents. This study examined whether latent classes of baseline alcohol and prescription drug misuse longitudinally predict SV and TDV victimization and perpetration (i.e., verbal,relational, physical/threatening, and sexual) 1 year later. MethodsStudents from six Midwestern high schools (n = 1,875; grades 9–11) completed surveys across two consecutive spring semesters. Latent class analysis was used to identify classes of individuals according to four substance use variables. A latent class regression and a manual three-step auxiliary approach were used to assess concurrent and distal relationships between identified classes and SV and TDV victimization and perpetration. ResultsThree classes of substance use were identified: low/no use (41% of sample), alcohol only use (45%), and alcohol and prescription drug misuse (APD) (14%). Youth in the APD class experienced greater SV and TDV victimization and perpetration than the alcohol only class at baseline. At Time 2 (one year later), youth in the baseline APD class experienced significantly higher SV and TDV victimization and perpetration outcomes than youth in the alcohol only class with the exception of sexual and physical TDV perpetration. ConclusionsThe misuse of both alcohol and prescription drugs emerged as a significant risk factor for later SV and TDV among adolescents. As such, it would be beneficial if future research continued to assess the nature of these associations and incorporate prescription drug use and misuse into heath education,substance use, and violence prevention programs.

Transitions in the use of multiple substances from adolescence to young adulthood

BackgroundResearch indicates that many adolescents frequently use multiple substances. This study examines stability and transitions in the use and co-use of multiple substances (cigarette, alcohol, marijuana, illicit drugs) from adolescence to young adulthood. MethodsData were collected biennially from 662 youth in six assessments across ten years (2003–2013). We used latent class analysis (LCA) to classify youth by substances used at each wave and used latent transition analysis (LTA) to examine transition probabilities across waves. ResultsAt each wave, a three-class model best fit the data. Classes included a poly-use class, that had the highest probabilities of use among all substances, a co-use class, that had high probabilities of use of alcohol and marijuana, and an alcohol-dominate class that started with low probabilities of use among all substances but showed increasing probabilities of alcohol use, at later ages. LTA showed that the probability of remaining in the poly-use class was the most stable from one wave to the next, followed by the alcohol-dominate class, and the co-use class. The most transitions occurred for the co-use class, with more individuals transitioning to the poly-use class than to the alcohol-dominate class. ConclusionsStrong stability among adolescent substance use classes was found between waves. Transitions were typically to classes using more substances, although, transitions to use fewer substances was evident for some individuals. Distinguishing stable and transitioning classes of substance use and co-use provides opportunities for prevention and intervention to disrupt high-risk use classes.

Assessing the longitudinal stability of latent classes of substance use among gay, bisexual, and other men who have sex with men

BackgroundAssociation between substance use and HIV-risk among gay and bisexual men (GBM) is well documented. However, their substance use patterns are diverse, and it is unknown whether self-reported use patterns are stable over time. MethodsSexually-active GBM, aged >16 years, were recruited in Metro Vancouver using respondent-driven sampling and followed across 5 study visits at six-month intervals (n = 449). To identify distinct patterns of substance use and their longitudinal stability, Latent Transition Analysis (LTA) was conducted for drugs reported by at least 30 participants. Intraclass correlation coefficients (ICC) quantified the stability of class assignments. ResultsSix classes characterizing ‘limited drug use’ (i.e., low use of all drugs, except alcohol), ‘conventional drug use’ (i.e., use of alcohol, marijuana, and tobacco), ‘club drug use’ (i.e., use of alcohol, cocaine, and psychedelics), ‘sex drug use’ (i.e., use of alcohol, crystal meth, GHB, poppers, and erectile dysfunction drugs), ‘street drug use’ (i.e., use of alcohol and street opioids) and ‘assorted drug use’ (i.e., use of most drugs) were identified. Across five visits (2.5 years), 26.3% (n = 118/449) of GBM transitioned between classes. The prevalence of limited use trended upwards (Baseline:24.5%, Visit 5:28.3%, p < 0.0001) and assorted use trended downwards (13.4%–9.6%, p = 0.001). All classes had strong longitudinal stability (ICC > 0.97). ConclusionThe stability of latent substance use patterns highlight the utility of these measures in identifying patterns of substance use among people who use drugs – potentially allowing for better assessment of these groups and interventions related to their health.

Latent Classes of Substance Use Among American Indian and White Students Living on or Near Reservations, 2009-2013.

American Indian adolescents who reside on or near reservations report higher levels of substance use than adolescents in other racial/ethnic groups. Little research has addressed patterns of use, which have important implications for prevention and treatment planning. The objective of our study was to describe substance use among a large, population-based sample of American Indian and white students who lived on or near reservations. We obtained data from 4964 students in grades 7-12 attending 46 schools on or near reservations throughout the United States during 4 academic years (2009-2013). Measures assessed current substance use for alcohol, heavy drinking, marijuana, cigarettes, inhalants, and other drugs. We used latent class analysis to identify patterns of substance use by grade group (grades 7-8 and grades 9-12) and race (American Indian or white). For American Indians in both grade groups, we found 4 classes of substance use (in order of size): (1) nonusers; (2) marijuana and cigarette users; (3) alcohol, marijuana, and cigarette users; and (4) polysubstance users. For white students, we found 2 classes (nonusers and polysubstance users) among younger students and 4 classes (nonusers; alcohol, marijuana, and cigarette users; alcohol and cigarette users; and polysubstance users) among older students. We found significant differences in substance use patterns, especially at younger ages, between reservation American Indian students and white students attending the same schools. Combinations of substances used by American Indian adolescents were most likely to include marijuana, as compared with alcohol for white adolescents. Identifying subpopulations of users allows the design of interventions that will more efficiently and effectively address prevention and treatment needs of groups of individuals than would a one-size-fits-all approach.

F129. COMBINED PATTERNS OF TOBACCO AND CANNABIS USE IN ADOLESCENCE AND THEIR ASSOCIATION WITH PSYCHOTIC EXPERIENCES: A LONGITUDINAL ANALYSIS

BackgroundThere has been increasing concern about potentially causal effects of tobacco use on psychosis, but epidemiological studies have been less robust in attempts to minimise effects of confounding than studies of cannabis use have been. We therefore aim to examine the association of patterns of cigarette and cannabis use with preceding and subsequent psychotic experiences, and compare patterns of confounding across these patterns.MethodsWe analysed repeated measures of cigarette and cannabis use during adolescence in a sample of 5,300 individuals in the Avon Longitudinal Study of Parents and Children birth cohort who had at least 3 measures of cigarette and cannabis use between ages 14–19 years. Cigarette and cannabis use data were summarised using longitudinal latent class analysis to identify longitudinal classes of substance use, and associations between classes and psychotic experiences at 18 years were assessed.ResultsPrior to adjusting for a range of potential confounders, there was strong evidence that early-onset cigarette-only use (4.3%), early-onset cannabis use (3.2%), and late-onset cannabis use (11.9%), but not later-onset cigarette-only use (14.8%) latent classes were associated with increased psychotic experiences compared to non-users (65.9%) (omnibus P<0.001). After adjusting for confounders, the association for early-onset cigarette-only use attenuated substantially (unadjusted odds ratio (OR) = 3.03, 95%CI 1.13, 8.14; adjusted OR = 1.78, 95%CI 0.54, 5.88), whereas those for early-onset (adjusted OR = 3.70, 95%CI 1.66, 8.25) and late-onset (adjusted OR = 2.97, 95%CI 1.63, 5.40) cannabis use were unchanged.DiscussionOur findings indicate that whilst individuals who use either cannabis or cigarettes during adolescence have an increased risk of developing subsequent psychotic experiences, the epidemiological evidence for this being causal is substantively more robust for cannabis than it is for tobacco

T128. THE ASSOCIATION BETWEEN GENETIC RISK FOR SCHIZOPHRENIA AND PATTERNS OF CIGARETTE AND CANNABIS USE IN ADOLESCENCE

BackgroundSchizophrenia is associated with a higher prevalence of cannabis use and cigarette use. However, it is unknown to what extent these associations are due to a shared genetic aetiology. We therefore aim to examine how schizophrenia genetic risk associates with patterns of cigarette and cannabis use in adolescence.MethodsWe analysed repeated measures of cigarette and cannabis use during adolescence in a sample of 5,300 individuals in the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort who had at least 3 measures of cigarette and cannabis use between ages 14–19 years. Cigarette and cannabis use data were summarised using longitudinal latent class analysis to identify longitudinal classes of substance use, and associations between polygenic scores for schizophrenia and resulting classes were assessed.ResultsThe schizophrenia polygenic score based on single nucleotide polymorphisms (SNPs) meeting a discovery sample threshold of p ≤ 0.05 was associated with late onset cannabis use as compared to non-use (OR = 1.20; 95% CI = 1.05, 1.37) but not with early onset or cigarette only use latent classes. This association persisted after excluding the CHRNA5-CHRNA3-CHRNB4 nicotinic receptor gene cluster (OR = 1.25; 95% CI = 1.08, 1.44), a locus which has previously been found to strongly associate with schizophrenia.DiscussionThis study found that genetic risk of schizophrenia (as captured by polygenic scores) is associated with late-onset cannabis use but not with other smoking phenotypes in adolescence in ALSPAC. Possible explanations for these results are that schizophrenia and cannabis use have a shared genetic aetiology or that biological risk of schizophrenia leads to cannabis use through secondary mechanisms. These secondary mechanisms may include stress of childhood behavioural problems occurring as a result of biological processes underling schizophrenia. Future analyses involving mediation models may shed some light on factors influencing patterns of substance use in individuals with a high genetic liability for schizophrenia.