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Brick LA, Benca-Bachman CE, Johnson EC, Gustavson DE, Carper M, Palmer RHC. Genetic associations among internalizing and externalizing traits with polysubstance use among young adults. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.04.04.23287779. [PMID: 37066212 PMCID: PMC10104191 DOI: 10.1101/2023.04.04.23287779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Though most genetic studies of substance use focus on specific substances in isolation or generalized vulnerability across multiple substances, few studies to date focus on the concurrent use of two or more substances within a specified time frame (i.e., polysubstance use; PSU). We evaluated whether distinct genetic factors underlying internalizing and externalizing traits were associated with past 30-day PSU above variance shared across general psychopathology and substance use (SU). Using Genomic Structural Equation Modeling, we constructed theory-driven, multivariate genetic factors of 16 internalizing, externalizing, and SU traits using genome-wide association studies (GWAS) summary statistics. Next, we fit a model with a higher order SU-related psychopathology factor as well as genetic variance specific to externalizing and internalizing (i.e., residual genetic variance not explained by SU or general psychopathology). GWAS-by-subtraction was used to obtain single nucleotide polymorphism effects on each of these factors. Polygenic scores (PGS) were then created in an independent target sample with data on PSU, the National Longitudinal Study of Adolescent to Adult Health. To evaluate the effect of genetic variance due to internalizing and externalizing traits independent of variance related to SU, we regressed PSU on the PGSs, controlling for sex, age, and genetic principal components. PGSs for SU-related psychopathology and non-SU externalizing traits were associated with higher PSU factor scores, while the non-SU internalizing PGS was not significantly associated with PSU. In total, the three PGSs accounted for an additional 4% of the variance in PSU above and beyond a null model with only age, sex, and genetic principal components as predictors. These findings suggest that there may be unique genetic variance in externalizing traits contributing to liability for PSU that is independent of the genetic variance shared with SU.
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Affiliation(s)
- Leslie A Brick
- Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, Providence, Rhode Island, USA
- Providence VA Medical Center, Providence, Rhode Island, USA
- Behavioral Genetics of Addiction Laboratory, Department of Psychology at Emory University, Atlanta, Georgia, USA
| | - Chelsie E Benca-Bachman
- Providence VA Medical Center, Providence, Rhode Island, USA
- Behavioral Genetics of Addiction Laboratory, Department of Psychology at Emory University, Atlanta, Georgia, USA
| | - Emma C Johnson
- Department of Psychiatry, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Daniel E. Gustavson
- Institute for Behavioral Genetics, University of Colorado Boulder, Boulder, Colorado, USA
| | - Matthew Carper
- Department of Clinical Psychology, William James College, Newton, Massachusetts, USA
| | - Rohan HC Palmer
- Providence VA Medical Center, Providence, Rhode Island, USA
- Behavioral Genetics of Addiction Laboratory, Department of Psychology at Emory University, Atlanta, Georgia, USA
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Verweij KJH, Vink JM, Abdellaoui A, Gillespie NA, Derks EM, Treur JL. The genetic aetiology of cannabis use: from twin models to genome-wide association studies and beyond. Transl Psychiatry 2022; 12:489. [PMID: 36411281 PMCID: PMC9678872 DOI: 10.1038/s41398-022-02215-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 09/26/2022] [Accepted: 10/03/2022] [Indexed: 11/22/2022] Open
Abstract
Cannabis is among the most widely consumed psychoactive substances worldwide. Individual differences in cannabis use phenotypes can partly be explained by genetic differences. Technical and methodological advances have increased our understanding of the genetic aetiology of cannabis use. This narrative review discusses the genetic literature on cannabis use, covering twin, linkage, and candidate-gene studies, and the more recent genome-wide association studies (GWASs), as well as the interplay between genetic and environmental factors. Not only do we focus on the insights that these methods have provided on the genetic aetiology of cannabis use, but also on how they have helped to clarify the relationship between cannabis use and co-occurring traits, such as the use of other substances and mental health disorders. Twin studies have shown that cannabis use is moderately heritable, with higher heritability estimates for more severe phases of use. Linkage and candidate-gene studies have been largely unsuccessful, while GWASs so far only explain a small portion of the heritability. Dozens of genetic variants predictive of cannabis use have been identified, located in genes such as CADM2, FOXP2, and CHRNA2. Studies that applied multivariate methods (twin models, genetic correlation analysis, polygenic score analysis, genomic structural equation modelling, Mendelian randomisation) indicate that there is considerable genetic overlap between cannabis use and other traits (especially other substances and externalising disorders) and some evidence for causal relationships (most convincingly for schizophrenia). We end our review by discussing implications of these findings and suggestions for future work.
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Affiliation(s)
- Karin J. H. Verweij
- grid.7177.60000000084992262Department of Psychiatry, Amsterdam UMC, University of Amsterdam, Meibergdreef 5, 1105 AZ Amsterdam, The Netherlands
| | - Jacqueline M. Vink
- grid.5590.90000000122931605Behavioural Science Institute, Radboud University Nijmegen, Thomas van Aquinostraat 4, 6525 GD Nijmegen, The Netherlands
| | - Abdel Abdellaoui
- grid.7177.60000000084992262Department of Psychiatry, Amsterdam UMC, University of Amsterdam, Meibergdreef 5, 1105 AZ Amsterdam, The Netherlands
| | - Nathan A. Gillespie
- grid.224260.00000 0004 0458 8737Virginia Institute for Psychiatric and Behavior Genetics, Virginia Commonwealth University, 800 East Leigh St, Suite 100, Richmond, VA 23219 USA
| | - Eske M. Derks
- grid.1049.c0000 0001 2294 1395Translational Neurogenomics, QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, QLD 4006 Australia
| | - Jorien L. Treur
- grid.7177.60000000084992262Department of Psychiatry, Amsterdam UMC, University of Amsterdam, Meibergdreef 5, 1105 AZ Amsterdam, The Netherlands
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