Lindsey A Hines1, Katherine I Morley1, Fruhling Rijsdijk2, John Strang1, Arpana Agrawal3, Elliot C Nelson3, Dixie Statham4, Nicholas G Martin5, Michael T Lynskey1. 1. Addictions Department,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,England. 2. Social Genetic and Developmental Psychiatry Centre,Institute of Psychiatry,Psychology and Neuroscience,King's College London,London,England. 3. Department of Psychiatry,Washington University School of Medicine,St Louis,MO,USA. 4. School of Social Sciences,University of the Sunshine Coast,Queensland,Australia. 5. QIMR Berghofer Medical Research Institute,Brisbane,Queensland,Australia.
Abstract
BACKGROUND: The genetic component of Cannabis Use Disorder may overlap with influences acting more generally on early stages of cannabis use. This paper aims to determine the extent to which genetic influences on the development of cannabis abuse/dependence are correlated with those acting on the opportunity to use cannabis and frequency of use. METHODS: A cross-sectional study of 3303 Australian twins, measuring age of onset of cannabis use opportunity, lifetime frequency of cannabis use, and lifetime DSM-IV cannabis abuse/dependence. A trivariate Cholesky decomposition estimated additive genetic (A), shared environment (C) and unique environment (E) contributions to the opportunity to use cannabis, the frequency of cannabis use, cannabis abuse/dependence, and the extent of overlap between genetic and environmental factors associated with each phenotype. RESULTS: Variance components estimates were A = 0.64 [95% confidence interval (CI) 0.58-0.70] and E = 0.36 (95% CI 0.29-0.42) for age of opportunity to use cannabis, A = 0.74 (95% CI 0.66-0.80) and E = 0.26 (95% CI 0.20-0.34) for cannabis use frequency, and A = 0.78 (95% CI 0.65-0.88) and E = 0.22 (95% CI 0.12-0.35) for cannabis abuse/dependence. Opportunity shares 45% of genetic influences with the frequency of use, and only 17% of additive genetic influences are unique to abuse/dependence from those acting on opportunity and frequency. CONCLUSIONS: There are significant genetic contributions to lifetime cannabis abuse/dependence, but a large proportion of this overlaps with influences acting on opportunity and frequency of use. Individuals without drug use opportunity are uninformative, and studies of drug use disorders must incorporate individual exposure to accurately identify aetiology.
BACKGROUND: The genetic component of Cannabis Use Disorder may overlap with influences acting more generally on early stages of cannabis use. This paper aims to determine the extent to which genetic influences on the development of cannabis abuse/dependence are correlated with those acting on the opportunity to use cannabis and frequency of use. METHODS: A cross-sectional study of 3303 Australian twins, measuring age of onset of cannabis use opportunity, lifetime frequency of cannabis use, and lifetime DSM-IV cannabis abuse/dependence. A trivariate Cholesky decomposition estimated additive genetic (A), shared environment (C) and unique environment (E) contributions to the opportunity to use cannabis, the frequency of cannabis use, cannabis abuse/dependence, and the extent of overlap between genetic and environmental factors associated with each phenotype. RESULTS: Variance components estimates were A = 0.64 [95% confidence interval (CI) 0.58-0.70] and E = 0.36 (95% CI 0.29-0.42) for age of opportunity to use cannabis, A = 0.74 (95% CI 0.66-0.80) and E = 0.26 (95% CI 0.20-0.34) for cannabis use frequency, and A = 0.78 (95% CI 0.65-0.88) and E = 0.22 (95% CI 0.12-0.35) for cannabis abuse/dependence. Opportunity shares 45% of genetic influences with the frequency of use, and only 17% of additive genetic influences are unique to abuse/dependence from those acting on opportunity and frequency. CONCLUSIONS: There are significant genetic contributions to lifetime cannabis abuse/dependence, but a large proportion of this overlaps with influences acting on opportunity and frequency of use. Individuals without drug use opportunity are uninformative, and studies of drug use disorders must incorporate individual exposure to accurately identify aetiology.
Authors: Jason P Connor; Daniel Stjepanović; Bernard Le Foll; Eva Hoch; Alan J Budney; Wayne D Hall Journal: Nat Rev Dis Primers Date: 2021-02-25 Impact factor: 52.329
Authors: Stephanie M Zellers; Robin Corley; Eric Thibodeau; Robert Kirkpatrick; Irene Elkins; William G Iacono; Christian Hopfer; John K Hewitt; Matt McGue; Scott Vrieze Journal: Behav Genet Date: 2020-02-08 Impact factor: 2.805
Authors: Lindsey A Hines; Tom P Freeman; Suzanne H Gage; Stanley Zammit; Matthew Hickman; Mary Cannon; Marcus Munafo; John MacLeod; Jon Heron Journal: JAMA Psychiatry Date: 2020-10-01 Impact factor: 21.596