Connectivity Changes Following Episodic Future Thinking in Alcohol Use Disorder.

[Please note that in order to respond to reviewers request we had exceed the 300 word limit. The following is NOT revised from the first submission, please see the actual revised manuscript file for the reviewer-driven changes]. INTRODUCTION: Recent addiction and obesity-related research suggest that episodic future thinking (EFT) can serve as a promising intervention to promote healthy decision making. This study investigated the neural effects of EFT in alcohol use disorder (AUD). METHODS: Participants received either a brief EFT or control intervention to examine differences in resting-state connectivity. We then used these findings to characterize psychophysiological interaction (PPI) differences during a delay discounting (DD) fMRI task. In addition, we used a second control group of AUD participants without any intervention to reproduce and aid in interpreting our key findings. RESULTS: EFT participants, but not controls, showed statistically improved discounting rates - a behavioral marker for addiction. Resting state analyses of the left hippocampus revealed connectivity differences in the frontal poles. The directionality of this difference suggested that EFT reduced a hypoconnectivity relationship between these regions in AUD. We also found resting state connectivity differences between the salience network and the right dorsolateral prefrontal cortex (R DLPFC), which then led us to discover R-to-L DLPFC PPI differences during DD. Moreover, the resting state salience-to-DLPFC functional connectivity showed an inverse relationship to discounting rate while hyperconnectivity between left and right DLPFC reflected slower reaction times during difficult DD trials. DISCUSSION: These findings suggest that EFT produces beneficial changes in neural connectivity patterns in AUD. The alterations in connectivity highlight potential mechanisms underlying the effectiveness of EFT in improving decision-making in AUD. Understanding these neural effects may contribute to the further development of targeted interventions for AUD and related disorders.

Using Latent Profile Analysis to Characterize Clinical Heterogeneity and Impulsivity in a Large Residential Addiction Treatment Program.

Objectives: Clinical heterogeneity among patients in addiction treatment settings represents a challenge as most of the treatment programs are designed to treat substance use disorders (SUD) generally rather than offering more tailored approaches addressing individual patient needs. Systematic characterization of clinical heterogeneity may permit more individualized care paths toward improving outcomes. Methods: Data were collected from a large inpatient SUD treatment program between April 2018 and March 2020 (n = 1519). Latent profile analysis (LPA) was applied to identify latent clusters based on differences in substance use and co-occurring depression, anxiety, and post-traumatic stress disorder. Results: Five distinct profiles emerged: Profile 1 (38%) exhibited the lowest substance use and lowest psychiatric severity (Overall Low); Profile 2 (39%) exhibited high alcohol and psychiatric severity; Profile 3 (13%) exhibited high opioid severity and low psychiatric severity. Profile 4 (8%) exhibited high cannabis use and high psychiatric severity, and profile 5 (3%) exhibited high polysubstance use other than alcohol and cannabis use. The latter two profiles were younger and exhibited higher self-regulatory deficits. The (High Alc/high psych) and the (High Cann/Psych) profiles exhibited differentially higher psychiatric severity. Profiles showing high polysubstance use, as well as high cannabis use and high psychiatric severity, showed significantly higher impulsive behavior than the others. Conclusions: LPA revealed five clusters of patients varying substantially in terms of SUD and psychiatric severity. Addressing common features of clinical heterogeneity for tailored care paths in a personalized treatment approach may improve treatment outcomes.

Triple network resting-state functional connectivity patterns of alcohol heavy drinking.

AIMS: Previous neuroimaging research in alcohol use disorder (AUD) has found altered functional connectivity in the brain's salience, default mode, and central executive (CEN) networks (i.e. the triple network model), though their specific associations with AUD severity and heavy drinking remains unclear. This study utilized resting-state fMRI to examine functional connectivity in these networks and measures of alcohol misuse. METHODS: Seventy-six adult heavy drinkers completed a 7-min resting-state functional MRI scan during visual fixation. Linear regression models tested if connectivity in the three target networks was associated with past 12-month AUD symptoms and number of heavy drinking days in the past 30 days. Exploratory analyses examined correlations between connectivity clusters and impulsivity and psychopathology measures. RESULTS: Functional connectivity within the CEN network (right and left lateral prefrontal cortex [LPFC] seeds co-activating with 13 and 15 clusters, respectively) was significantly associated with AUD symptoms (right LPFC: ß = .337, p-FDR = .016; left LPFC: ß = .291, p-FDR = .028) but not heavy drinking (p-FDR > .749). Post-hoc tests revealed six clusters co-activating with the CEN network were associated with AUD symptoms-right middle frontal gyrus, right inferior parietal gyrus, left middle temporal gyrus, and left and right cerebellum. Neither the default mode nor the salience network was significantly associated with alcohol variables. Connectivity in the left LPFC was correlated with monetary delay discounting (r = .25, p = .03). CONCLUSIONS: These findings support previous associations between connectivity within the CEN network and AUD severity, providing additional specificity to the relevance of the triple network model to AUD.

Longitudinal characterization of impulsivity phenotypes boosts signal for genomic correlates and heritability.

Genomic correlates of impulsivity have been identified in several genome-wide association studies (GWAS) using cross-sectional designs, but no studies have investigated the molecular genetic correlates of impulsivity phenotypes using longitudinally constructed traits. In 3860 unrelated European participants in the Avon Longitudinal Study of Parents and Children (ALSPAC), we constructed longitudinal phenotypes for delay discounting and impulsive personality traits (as measured by the UPPS-P impulsive behavior scales) via assessment at ages 24, 26, and 28. We conducted GWASs of impulsivity using both cross-sectional and longitudinal phenotypes, estimated heritability and their phenotypic and genetic correlations, and evaluated their association with recently-developed polygenic risk scores (PRSs) for the impulsivity indicators themselves and also related psychiatric conditions. Latent growth curve modeling revealed a stable intercept over time for all impulsivity phenotypes. High genetic correlation of cross-sectional measures over time suggested a stable genetic component for delay discounting (rg = 0.53-0.99) and sensation seeking (rg = 0.99). Heritability estimates of the stable longitudinal phenotypes substantively improved as compared to their cross-sectional counterparts, revealing a significant SNP-heritability for delay discounting (0.22; p = 0.03) and sensation seeking (0.35; p = 0.0007). Consistent with previous reports, GWAS and gene-based analyses revealed associations between specific longitudinal impulsivity indicators and CADM2 and NCAM1 genes. The PRSs for the impulsivity indicators and disorders related to self-regulation were also significantly associated with longitudinal impulsivity traits. Finally, we validated the associations between longitudinal impulsivity phenotypes and their PRSs in an independent 13-wave longitudinal study (n = 1019) and the benefit of longitudinal phenotypes in simulation studies. In this first longitudinal genetic study of impulsivity traits, the results revealed stable genomic correlates of delay discounting and sensation seeking over time and further validated the utility of recently-developed PRSs, both in relation to the observed traits and in connecting them to psychiatric disorders. More generally, these findings support using latent intercepts as novel longitudinal phenotypes to boost signal for heritability and genomic correlates of mechanisms contributing to psychiatric disease liability.

Psilocybin for clinical indications: A scoping review.

BACKGROUND: Psychedelic drugs have been of interest in medicine since the early 1950s. There has recently been a resurgence of interest in psychedelics. AIMS: The objective of this study is to determine the extent of the available literature on psilocybin for medical indications including the designs used, study characteristics, indications studied, doses, and authors' conclusions. We identify areas for further study where there are research gaps. METHODS: We conducted a systematic scoping review of clinical indications for psilocybin, encompassing psychiatric and medical conditions. We systematically searched Medline and Embase using keywords related to psilocybin. We reviewed titles and texts in duplicate using Covidence software. We extracted data individually in duplicate using Covidence software and a senior reviewer resolved all author conflicts. We analyzed data descriptively. RESULTS: We included 193 published and 80 ongoing studies. Thirty-seven percent of included studies were systematic reviews. Only 12% of included studies were randomized controlled trials. The median number of participants was 22 with a median of 18 participants who had taken psilocybin. Thirty-eight percent of studies reported at least one potential conflict of interest. The most common indication was depression (28%). Also commonly studied were substance use (14%), mental health in life-threatening illness (9%), headaches (6%), depression and anxiety (6%), obsessive-compulsive disorder (3%), and anxiety disorders (3%). CONCLUSIONS: Most studies involving the administration of psilocybin have small sample sizes and the most common focus has been psychiatric disorders. There is a need for high-quality randomized trials on psilocybin and to expand consideration to other promising indications, such as chronic pain.

Behavioral economic analysis of the comorbidity of alcohol problems and posttraumatic stress: Findings from high-risk young adults and general community adults.

A behavioral economic reinforcer pathology model theorizes that alcohol problems are influenced by steep delay discounting, overvaluation of alcohol reinforcement, and low reinforcement from alcohol-free activities. Extending this account to the comorbidity of alcohol problems and posttraumatic stress disorder (PTSD), the present study tested the hypothesis that alcohol problems and PTSD symptom severity would interact and be positively associated with indicators from these three domains. High-risk emerging adults from North America (Study 1, n = 1,311, Mage = 22.13) and general community adults from Canada (Study 2, n = 1,506, Mage = 36.80) completed measures of alcohol problems, PTSD symptoms, delay discounting, alcohol demand, and proportionate alcohol-related reinforcement. Across studies, regression analyses revealed significant main effects of alcohol problems and PTSD symptoms in relation to selected reinforcer pathology indicators, but no significant interactions were present for delay discounting or proportionate alcohol-related reinforcement. Interactions were observed for alcohol consumption at $0 (intensity) and the rate of change in consumption across the demand curve (elasticity; Study 1) and for elasticity and maximum alcohol expenditure (Omax; Study 2), but not in the predicted directions. Higher synergistic severity was associated with lower alcohol reinforcing value in each case. These findings reveal expected relations between reinforcer pathology indicators and both alcohol problems and PTSD symptomatology in general but did not support the hypothesized synergistic relationship. The relation between alcohol problems and PTSD is more complex than predicted by existing extensions of the reinforcer pathology model, warranting further investigation. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Empirical examination of working memory performance and its neural correlates in relation to delay discounting in two large samples.

The neurobiological basis of working memory and delay discounting are theorized to overlap, but few studies have empirically examined these relations in large samples. To address this, we investigated the association of neural activation during an fMRI N-Back working memory task with delay discounting area, as well as in- and out-of-scanner working memory measures. These analyses were conducted in two large task fMRI datasets, the Human Connectome Project and the Adolescent Brain Cognitive Development Study. Although in- and out-of-scanner working memory performance were significantly associated with N-back task brain activation regions, contrary to our hypotheses, there were no significant associations between working memory task activation and delay discounting scores. These findings call into question the extent of the neural overlap in delay discounting and working memory and highlight the need for more investigations directly interrogating overlapping and distinct brain regions across cognitive neuroscience tasks.

Label Accuracy of Legal Oral Cannabis Oil Products in Ontario, Canada.

This case series compares amounts of tetrahydrocannabinol and cannabidiol reported on product labels vs levels found in laboratory testing in legal oral cannabis oil products in Ontario, Canada.

Correspondence between the alcohol-P3 event-related potential and alcohol reward phenotypes among young adults.

BACKGROUND: Behavioral economic theory suggests that the value of alcohol depends upon elements of the choice context, such that increasing constraints on alternatives (e.g., price) or increasing the benefits of alcohol (e.g., social context) may result in greater likelihood of heavy drinking. The P3 event-related potential elicited by alcohol-related cues, a proposed marker of incentive salience, may be an electrophysiological parallel for behavioral economic alcohol demand. However, these indices have not been connected in prior research, and studies typically do not disaggregate social influences in the context of alcohol cue reactivity. METHOD: The current study recruited heavy drinking young adults (N = 81) who completed measures of alcohol use and alcohol demand, in addition to a 2 (social/nonsocial) × 2 (alcohol/nonalcohol) visual oddball task to elicit the P3. RESULTS: In multilevel models controlling for demographic characteristics, P3 reactivity was greater to alcohol (p < 0.001) and social (p < 0.001) cues than to nonalcohol and nonsocial cues, but without a significant interaction. Higher alcohol consumption (p = 0.02) and lower elasticity of demand (p = 0.01) were associated with greater P3 response to alcohol than nonalcohol cues. CONCLUSIONS: The results highlight a brain-behavior connection that may be an important marker for alcohol reward across units of analysis and may be sensitive to changes in the economic choice contexts that influence the likelihood of alcohol use.

Clinical efficacy of deep transcranial magnetic stimulation (dTMS) in psychiatric and cognitive disorders: A systematic review.

Deep transcranial magnetic stimulation (dTMS) has gained attention as an enhanced form of traditional TMS, targeting broader and deeper regions of the brain. However, a fulsome synthesis of dTMS efficacy across psychiatric and cognitive disorders using sham-controlled trials is lacking. We systematically reviewed 28 clinical trials comparing active dTMS to a sham/controlled condition to characterize dTMS efficacy across diverse psychiatric and cognitive disorders. A comprehensive search of APA PsycINFO, Cochrane, Embase, Medline, and PubMed databases was conducted. Predominant evidence supports dTMS efficacy in patients with obsessive-compulsive disorder (OCD; n = 2), substance use disorders (SUDs; n = 8), and in those experiencing depressive episodes with major depressive disorder (MDD) or bipolar disorder (BD; n = 6). However, the clinical efficacy of dTMS in psychiatric disorders characterized by hyperactivity or hyperarousal (i.e., attention-deficit/hyperactivity disorder, posttraumatic stress disorder, and schizophrenia) was heterogeneous. Common side effects included headaches and pain/discomfort, with rare but serious adverse events such as seizures and suicidal ideation/attempts. Risk of bias ratings indicated a collectively low risk according to the Grading of Recommendations, Assessment, Development, and Evaluations checklist (Meader et al., 2014). Literature suggests promise for dTMS as a beneficial alternative or add-on treatment for patients who do not respond well to traditional treatment, particularly for depressive episodes, OCD, and SUDs. Mixed evidence and limited clinical trials for other psychiatric and cognitive disorders suggest more extensive research is warranted. Future research should examine the durability of dTMS interventions and identify moderators of clinical efficacy.

Psychometric Validation of the Gambling Craving Scale in a Treatment-Seeking Sample.

The Gambling Craving Scale (GACS) is a multifaceted measure of gambling craving. Initial validation work by Young and Wohl (2009) in university student samples showed that the GACS had a three-factor structure capturing dimensions of Desire, Anticipation, and Relief. Despite its potential clinical utility as a measure of craving, the GACS has yet to be validated in people seeking treatment for gambling problems. Accordingly, we examined the psychometric properties in a sample of people (N = 209; Mage = 37.66; 62.2% female) participating in a randomized controlled trial testing a novel online treatment for problem gambling. We predicted the GACS would have a three-factor structure. In addition, we also examined measurement invariance across sex and problem gambling risk status. Finally, we assessed concurrent validity of the factors with other measures of problem gambling severity and involvement. Exploratory structural equation modeling findings supported a three-factor structure that was invariant across the groups tested. Each of the Desire, Anticipation, and Relief subscales were significant positive predictors of problem gambling severity and symptoms, and some form of gambling behaviour. Findings show the GACS is a promising scale to assess multidimensional craving experiences among people in treatment for gambling problems.

Neurobiological foundations and clinical relevance of effort-based decision-making.

Applying effort-based decision-making tasks provides insights into specific variables influencing choice behaviors. The current review summarizes the structural and functional neuroanatomy of effort-based decision-making. Across 39 examined studies, the review highlights the ventromedial prefrontal cortex in forming reward-based predictions, the ventral striatum encoding expected subjective values driven by reward size, the dorsal anterior cingulate cortex for monitoring choices to maximize rewards, and specific motor areas preparing for effort expenditure. Neuromodulation techniques, along with shifting environmental and internal states, are promising novel treatment interventions for altering neural alterations underlying decision-making. Our review further articulates the translational promise of this construct into the development, maintenance and treatment of psychiatric conditions, particularly those characterized by reward-, effort- and valuation-related deficits.

Changing cannabis legislation in Canada and a longitudinal look at "regular" cannabis use in patients with eating disorders.

Regular cannabis use (CU), defined as "weekly or more often", is associated with a number of negative mental health outcomes. In the last decade, Canada legalized first medical and then recreational CU. Despite higher prevalence in mental health populations, little research has documented changes in frequency of CU with progressive legalization of cannabis. This study examined rates of CU in a sample of 843 treatment-seeking patients with eating disorders (ED) in an outpatient setting between 2004 and 2020. Across ED diagnoses, segmented regression indicated a significant break-point in regular CU in 2014, commensurate with the relaxation of medical cannabis laws. Regular CU increased from 4.9 % to 23.7 % from 2014 to 2020; well above the stable 6 % found in the general population. No significant break-point was observed in either alcohol or illicit substance use over the same time period. Significant increases in regular CU were found in patients with anorexia nervosa and binge eating disorder, while regular use remained stable in patients with bulimia nervosa. Comorbid psychiatric diagnoses did not increase odds of regular CU. Findings suggest certain patient groups with mental illness may be at risk of engaging in high frequency use in the context of legislation implying medical benefits of cannabis.

Efficiently Quantifying Egocentric Social Network Cannabis Use: Initial Psychometric Validation of the Brief Cannabis Social Density Assessment.

OBJECTIVE: Social environment is a key determinant of substance use, but cannabis-related social network analysis is not common, in part due to the assessment burden of comprehensive egocentric social network analysis. METHOD: The current pre-registered secondary analysis assessed the psychometric properties (i.e., convergent, criterion-related, incremental validity) of the Brief Cannabis Social Density Assessment (B-CaSDA) in a cross-sectional sample of adults who use cannabis (N = 310) using a survey-based design. The B-CaSDA assesses the quantity and frequency of cannabis use for the respondent's four closest (non-parent) relationships. RESULTS: Cannabis use severity was elevated for each additional person who used cannabis at all or daily in the individual's social network. B-CaSDA indices (i.e., frequency, quantity, total score) were positively correlated with cannabis consumption, cannabis use severity indicators, and established risk factors for harmful cannabis use. B-CaSDA indices also discriminated between those above and below a clinical cutoff on the Cannabis Use Disorder Identification Test - Revised (CUDIT-R). Finally, in omnibus models that included common risk factors for cannabis use severity, the B-CaSDA quantity index contributed additional variance when predicting CUDIT-R total score, and B-CaSDA frequency contributed additional variance in predicting the CUDIT-R quantity-frequency subscale. CONCLUSIONS: The results suggest that the B-CaSDA has the potential to expand social network research on cannabis use and misuse by increasing its assessment feasibility in diverse designs.

Diagnostic discrimination of social network indicators in alcohol use disorder: Initial examination using high-resolution and brief assessments.

OBJECTIVE: Social network analysis (SNA) characterizes the structure and composition of a person's social relationships. Network features have been associated with alcohol consumption in observational studies, primarily of university undergraduates. No studies have investigated whether indicators from a person's social network can accurately identify the presence of alcohol use disorder (AUD), offering an indirect strategy for identifying AUD. METHOD: Two cross-sectional case-control designs examined the clinical utility of social network indicators for identifying individuals with AUD (cases) versus demographically matched drinkers without AUD (controls). Study 1 (N = 174) used high-resolution egocentric SNA assessment, whereas Study 2 (N = 189) used a brief assessment. RESULTS: In Study 1, significant differences between AUD+ participants and controls were present for network alcohol severity (i.e., heavy drinking days; d = 1.23) and frequency (d = 0.35), but not network structural features. Network alcohol severity exhibited very good classification of AUD+ individuals versus controls (area under the curve [AUC] = 0.80), whereas network frequency did not (AUC = 0.61). In Study 2, significant differences were present for network alcohol severity (d = 1.02), quantity (d = 0.74), and frequency (d = 0.43), and severity exhibited good differentiation (AUC = 0.76). CONCLUSIONS: Social network indicators of alcohol involvement robustly differentiated AUD+ individuals from matched controls, and the brief assessment performed almost as well as the high-resolution assessment. These findings provide proof-of-concept for severity-related SNA indicators as promising novel clinical assessments for AUD. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Computerized clinical decision support to improve stroke prevention therapy in primary care management of atrial fibrillation: a cluster randomized trial.

BACKGROUND: Despite guidelines supporting antithrombotic therapy use in atrial fibrillation (AF), under-prescribing persists. We assessed whether computerized clinical decision support (CDS) would enable guideline-based antithrombotic therapy for AF patients in primary care. METHODS: This cluster randomized trial of CDS versus usual care (UC) recruited participants from primary care practices across Nova Scotia, following them for 12 months. The CDS tool calculated bleeding and stroke risk scores and provided recommendations for using oral anticoagulants (OAC) per Canadian guidelines. RESULTS: From June 14, 2014 to December 15, 2016, 203 primary care providers (99 UC, 104 CDS) with access to high-speed Internet were recruited, enrolling 1,145 eligible patients (543 UC, 590 CDS) assigned to the same treatment arm as their provider. Patient mean age was 72.3 years; most were male (350, 64.5% UC, 351, 59.5% CDS) and from a rural area (298, 54.9% UC, 315, 53.4% CDS). At baseline, a higher than anticipated proportion of patients were receiving guideline-based OAC therapy (373, 68.7% UC, 442, 74.9% CDS; relative risk [RR] 0.97 (95% confidence interval [CI], 0.87-1.07; P = .511)). At 12 months, prescription data were available for 538 usual care and 570 CDS patients, and significantly more CDS patients were managed according to guidelines (415, 77.1% UC, 479, 84.0% CDS; RR 1.08 (95% CI, 1.01-1.15; P = .024)). CONCLUSION: Notwithstanding high baseline rates, primary care provider access to the CDS over 12 months further optimized the prescribing of OAC therapy per national guidelines to AF patients potentially eligible to receive it. This suggests that CDS can be effective in improving clinical process of care. TRIAL REGISTRATION: Clinical Trials NCT01927367. https://clinicaltrials.gov/ct2/show/NCT01927367?term=NCT01927367&draw=2&rank=1.

Using Measurement-Based Care as a Precision Medicine Strategy for Substance Use Disorders.

PURPOSE OF REVIEW: Precision medicine prioritizes characterization of individual patient parameters to optimize care and this review evaluates measurement-based care (MBC) as a strategy for doing so in the treatment of substance use disorders (SUD). Measurement-based care refers to the systematic use of validated assessments to inform diagnosis and treatment planning, with varying frequency of assessments. Despite the seemingly obvious grounds for the use of MBC in treating SUD, systematic implementation to date has been limited. Thus, the goal of this review is to evaluate efforts to date and to stimulate greater consideration of MBC models in addictions programs. RECENT FINDINGS: Data from two published randomized controlled trials and findings from pragmatic clinical research highlight the potential utility of MBC in the SUD treatment settings. Despite these findings, the existing literature indicates the high need for larger-scale clinical trials and quality improvement programs. Potential barriers to the implementation of MBC for SUD are outlined at the patient, provider, organization, and system levels, as well as the challenges associated with the use of MBC programs for clinical research. Critical thinking considerations and risk mitigation strategies are offered toward advancing MBC for SUD beyond the current nascent state. Collectively, the existing data confirm that MBC is a suitable and promising strategy for applying a precision medicine approach in SUD treatment, warranting further implementation efforts and scientific inquiry.

Neural correlates of increased alcohol demand following alcohol cue exposure in adult heavy drinkers.

Alcohol use disorder is associated with overvaluation of alcohol relative to other rewards, in part due to dynamic increases in value in response to alcohol-related cues. In a neuroeconomic framework, alcohol cues increase behavioral economic demand for alcohol, but the neural correlates these cue effects are unknown. This functional magnetic resonance imaging study combined a neuroeconomic alcohol purchase task with an alcohol cue exposure in 72 heavy drinkers with established sensitivity to alcohol cues (51 % female; mean age=33.74). Participants reported how many drinks they would consume from $0-$80/drink following exposure to neutral and alcohol images in a fixed order. Participants purchased significantly more drinks in the alcohol compared to the neutral condition, which was also evident for demand indices (i.e., intensity, breakpoint, Omax, elasticity; ps<0.001; ds=0.46-0.92). Alcohol purchase decisions were associated with activation in rostral middle and medial frontal gyri, anterior insula, posterior parietal cortex, and dorsal striatum, among other regions. Activation was lower across regions in the alcohol relative to neutral cue condition, potentially due to greater automaticity of choices in the presence of alcohol cues or attenuation of responses due to fixed cue order. These results contribute to growing literature using neuroeconomics to understand alcohol misuse and provide a foundation for future research investigating decision-making effects of environmental alcohol triggers.

Early substance use and the school environment: A multilevel latent class analysis.

Background: Early substance use is associated with increased risks for mental health and substance use problems which are compounded when using several substances (i.e., polysubstance use). A notable increase in substance use occurs when adolescents transition from elementary to secondary schooling. Objective: This study seeks to characterize student and school classes of substance use. Methods: A cross-sectional multilevel latent class analysis and regression was conducted on a representative sample of 19,130 grade 6-8 students from 180 elementary schools in Ontario, Canada to: 1) identify distinct classes of student substance use; 2) identify classes of schools based on student classes; and 3) explore correlates of these classes, including mental health, school climate, belonging, safety, and extracurricular participation. Results: Two student and two school classes were identified. 4.1% of students were assigned to the high probability of early polysubstance use class while the remaining 95.9% were in the low probability class. Students experiencing depressive and externalizing symptoms had higher odds of being in the early polysubstance use class (Odds Ratio [OR]s=1.1-1.25). At the school level, 19% of schools had higher proportions of students endorsing polysubstance use. Perceptions of positive school climate, belonging, and safety increased the odds of students being in the low probability of early polysubstance use student-level class (ORs=0.85-0.93) and lower probability of early polysubstance use school-level class. Associations related to extracurricular participation were largely not statistically significant. Conclusions: Student and school substance use classes may serve as targets for tailored prevention and early interventions. Results support examining school-based interventions targeting school climate, belonging, and safety.

Contexte: L'utilisation précoce de substances est associée à des risques accrus pour la santé mentale et les problèmes liés à l'utilisation de substances qui sont aggravés lorsque plusieurs substances sont utilisées (c.-à-d. utilisation de polysubstances). Une augmentation notable de l'utilisation de substances se produit quand les adolescents passent du cours primaire au cours secondaire. Objectif: La présente étude cherche à caractériser l'utilisation de substances chez les classes d'élèves et d'écoles. Méthodes: Une analyse transversale et une régression des classes latentes multi-niveaux ont été menées sur un échantillon représentatif de 19 130 élèves de la 6e à la 8e année de 180 écoles primaires de l'Ontario, Canada, pour: 1) identifier les classes d'élèves distinctes utilisant des substances; 2) identifier les classes d'écoles d'après les classes d'élèves; et 3) explorer les corrélats de ces classes, notamment la santé mentale, le climat scolaire, l'appartenance, la sécurité, et la participation extrascolaire. Résultats: Deux classes d'élèves et deux classes d'écoles ont été identifiées. Des élèves au nombre de 4,1 % ont été assignés à la classe probabilité élevée d'une utilisation précoce de polysubstances alors que les 95,9 % restants étaient dans la classe probabilité faible. Les élèves souffrant de dépression et de symptômes externalisants avaient des probabilités plus élevées d'être dans la classe utilisation précoce de polysubstances (Rapport de cotes [RC] = 1,1­1,25). Au niveau des écoles, 19 % d'entre elles avaient des proportions plus élevées d'élèves approuvant l'utilisation de polysubstances. Les perceptions positives du climat scolaire, de l'appartenance et de la sécurité accroissaient les probabilités d'élèves étant dans la classe d'élèves faible probabilité d'utilisation précoce de polysubstances (RC = 0,85­0,93) et une probabilité plus faible de la classe d'écoles ayant une utilisation précoce de polysubstances. Les associations liées à une participation extrascolaire étaient largement non significatives statistiquement. Conclusions: Les classes d'utilisation de substances d'élèves et d'écoles peuvent servir de cibles pour une prévention adaptée et des interventions précoces. Les résultats soutiennent l'examen des interventions en milieu scolaire qui ciblent le climat scolaire, l'appartenance et la sécurité.